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Microbiol. Res., Volume 14, Issue 4 (December 2023) – 45 articles

Cover Story (view full-size image): P. aeruginosa (Pa) and A. fumigatus (Af) are the most prominent bacterium and fungus in the airways of cystic fibrosis and immunocompromised patients. Each causes lung damage, especially in co-infection cases. Their interactions have been studied in vitro. We focused on the competition for iron (Fe), as shown in the figure. It shows the complexity; each microbe attempts to capture the available Fe via their siderophores, and they are dependent on the Fe content of the environment. The figure simplifies the competition by omitting every siderophore, Af toxins such as gliotoxin, fungal defensins, biosurfactants, and organic molecular volatiles. In this study, we examine competition in vivo. We show that the spatial arrangement affects it. Further studies, particularly in immunocompromised hosts, are needed. View this paper
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33 pages, 12592 KiB  
Article
Enhancing Understanding of the Impact of Climate Change on Malaria in West Africa Using the Vector-Borne Disease Community Model of the International Center for Theoretical Physics (VECTRI) and the Bias-Corrected Phase 6 Coupled Model Intercomparison Project Data (CMIP6)
Microbiol. Res. 2023, 14(4), 2148-2180; https://doi.org/10.3390/microbiolres14040145 - 18 Dec 2023
Viewed by 1233
Abstract
In sub-Saharan Africa, temperatures are generally conducive to malaria transmission, and rainfall provides mosquitoes with optimal breeding conditions. The objective of this study is to assess the impact of future climate change on malaria transmission in West Africa using community-based vector-borne disease models, [...] Read more.
In sub-Saharan Africa, temperatures are generally conducive to malaria transmission, and rainfall provides mosquitoes with optimal breeding conditions. The objective of this study is to assess the impact of future climate change on malaria transmission in West Africa using community-based vector-borne disease models, TRIeste (VECTRI). This VECTRI model, based on bias-corrected data from the Phase 6 Coupled Model Intercomparison Project (CMIP6), was used to simulate malaria parameters, such as the entomological inoculation rate (EIR). Due to the lack of data on confirmed malaria cases throughout West Africa, we first validated the forced VECTRI model with CMIP6 data in Senegal. This comparative study between observed malaria data from the National Malaria Control Program in Senegal (Programme National de Lutte contre le Paludisme, PNLP, PNLP) and malaria simulation data with the VECTRI (EIR) model has shown the ability of the biological model to simulate malaria transmission in Senegal. We then used the VECTRI model to reproduce the historical characteristics of malaria in West Africa and quantify the projected changes with two Shared Socio-economic Pathways (SSPs). The method adopted consists of first studying the climate in West Africa for a historical period (1950–2014), then evaluating the performance of VECTRI to simulate malaria over the same period (1950–2014), and finally studying the impact of projected climate change on malaria in a future period (2015–2100) according to the ssp245 ssp585 scenario. The results showed that low-latitude (southern) regions with abundant rainfall are the areas most affected by malaria transmission. Two transmission peaks are observed in June and October, with a period of high transmission extending from May to November. In contrast to regions with high latitudes in the north, semi-arid zones experience a relatively brief transmission period that occurs between August, September, and October, with the peak observed in September. Regarding projections based on the ssp585 scenario, the results indicate that, in general, malaria prevalence will gradually decrease in West Africa in the distant future. But the period of high transmission will tend to expand in the future. In addition, the shift of malaria prevalence from already affected areas to more suitable areas due to climate change is observed. Similar results were also observed with the ssp245 scenario regarding the projection of malaria prevalence. In contrast, the ssp245 scenario predicts an increase in malaria prevalence in the distant future, while the ssp585 scenario predicts a decrease. These findings are valuable for decision makers in developing public health initiatives in West Africa to mitigate the impact of this disease in the region in the context of climate change. Full article
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15 pages, 7425 KiB  
Article
Novel Vesicular Formulation Based on a Herbal Extract Loaded with Niosomes and Evaluation of Its Antimicrobial and Anticancer Potential
Microbiol. Res. 2023, 14(4), 2133-2147; https://doi.org/10.3390/microbiolres14040144 - 16 Dec 2023
Viewed by 734
Abstract
This study aimed to enhance the anticancer and antibacterial properties of Pistacia atlantica through a new parenteral formulation. The innovative approach involved loading P. atlantica fruit extract onto a novel Pluronic vesicular nano platform (Nio), analyzed using various techniques like GC-Mass, SEM, DLS, [...] Read more.
This study aimed to enhance the anticancer and antibacterial properties of Pistacia atlantica through a new parenteral formulation. The innovative approach involved loading P. atlantica fruit extract onto a novel Pluronic vesicular nano platform (Nio), analyzed using various techniques like GC-Mass, SEM, DLS, and UV-vis. The results revealed a stable, spherical Nio/Extract formulation of 103 ± 4.1 nm, possessing a high zeta potential of −30 ± 2.3 mV, with an impressive encapsulation efficiency of nearly 90 ± 3.5%. This formulation exhibited heightened cytotoxicity against BT-20 and MCF-10 cell lines compared to the extract alone, indicating its potential as a drug carrier with prolonged release characteristics. Additionally, the Nio/Extract demonstrated superior antibacterial effects against Pseudomonas aeruginosa, Staphylococcus epidermidis, and Candida albicans compared to the free extract, showcasing MIC values of 211, 147, and 187 ug/mL, respectively, versus 880, 920, and 960 ug/mL for the pathogens. These findings highlight the potential of niosomal nano-carriers housing P. atlantica extract as a viable therapeutic strategy for combating both malignancies and microbial infections. Full article
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20 pages, 3230 KiB  
Article
Fungal Endophytes of Moringa (Moringa oleifera L.), Neem (Azadirachta indica) and Lavender (Lavandula angustifolia) and Their Biological Control of Fusarium Wilt of Banana
Microbiol. Res. 2023, 14(4), 2113-2132; https://doi.org/10.3390/microbiolres14040143 - 15 Dec 2023
Viewed by 587
Abstract
Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), significantly affects the productivity of the banana crop in the field. Currently, there are no effective control measures available, and therefore, there is an urgent need to develop novel strategies to [...] Read more.
Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), significantly affects the productivity of the banana crop in the field. Currently, there are no effective control measures available, and therefore, there is an urgent need to develop novel strategies to control the spread of the disease. Biological control is a promising strategy for the management and control of the disease. The aim of this study was to identify fungal endophytes associated with Moringa (Moringa oleifera), Neem tree (Azadirachta indica) and Lavender (Lavandula angustifolia) and their antifungal activities against Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4). We isolated 69 fungal endophytes from different tissues of M. oleifera, A. indica and L. angustifolia and screened for antifungal activity against Foc TR4. Six fungal endophytes exhibited highest antagonistic activity against Foc TR4 based on dual-culture assays. Based on morphology and ITS gene sequence analysis, the selected six endophytes were identified to be related to Alternaria alternata (MB7 and NR3), Neofusicoccum parvum (LB1), Fusarium oxysporum (LR1), Talaromyces amestolkiae (MB14) and Alternaria tenuissima (NB6). The culture filtrates of the six fungal endophytes (LB1, LR1, MB7, MB14, NB6 and NR3) exhibited more than 50% inhibition of mycelial growth of Foc TR4 in vitro and were producers of β-1,3-glucanase. The six fungal endophytes showed biocontrol efficacy against Fusarium wilt in pot experiments. The findings from this study demonstrate that fungal endophytes LB1, LR1, MB7, MB14, NB6 and NR3 should be explored as biocontrol agents and biofertilizers in banana production. Full article
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8 pages, 1424 KiB  
Communication
Study of the Influence of the Temperature and Time of Microalgae Cultivation on the Reproduction Rate of Chlorella and Scenedesmus Microalgae When Cultured in a Tubular Photobioreactor
Microbiol. Res. 2023, 14(4), 2105-2112; https://doi.org/10.3390/microbiolres14040142 - 09 Dec 2023
Viewed by 828
Abstract
The use of algae for carbon dioxide fixation is based on their natural ability to photosynthesize. Dynamic experiments make it possible to calculate the short-term photosynthetic activity of microalgae strains in photobioreactors. In this study, the effect of temperature and culture time on [...] Read more.
The use of algae for carbon dioxide fixation is based on their natural ability to photosynthesize. Dynamic experiments make it possible to calculate the short-term photosynthetic activity of microalgae strains in photobioreactors. In this study, the effect of temperature and culture time on the intensity of reproduction and on CO2 absorption by some microalgae was evaluated. It was found that the maximum increase in biomass occurred during algae cultivation at 29–32 °C and pH = 8.4. A ratio of ~2.0 was observed between CO2 absorption and the increase in biomass for different microalgae. When using the Chlorella genus, the increase in biomass under comparable conditions was greater than when cultivating microalgae of the Scenedesmus genus. Full article
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15 pages, 2766 KiB  
Article
Assessment of the Impacts of Plant Growth-Promoting Micro-Organisms on Potato Farming in Different Climatic Conditions in Morocco
Microbiol. Res. 2023, 14(4), 2090-2104; https://doi.org/10.3390/microbiolres14040141 - 09 Dec 2023
Viewed by 526
Abstract
Environmental concerns are gradually reducing the global yield capacity of agricultural systems, with climate change representing the most significant challenge. Globally, Potatoes are the most essential non-cereal crop. Therefore, understanding the potential impacts of climate change on potato production is crucial for maintaining [...] Read more.
Environmental concerns are gradually reducing the global yield capacity of agricultural systems, with climate change representing the most significant challenge. Globally, Potatoes are the most essential non-cereal crop. Therefore, understanding the potential impacts of climate change on potato production is crucial for maintaining future global food security. This study aims to explore the roles played by PGPMs in two distinct regions, which are characterized by different climatic conditions, to assess their influence on two potato varieties, namely Siena and Bellini. Inoculation with these strains, particularly the Aureobasidium pullulans strains Ach1-1 and Ach1-2, resulted in significant improvements in growth and yield. In 2018, impressive yields of 194.1 kg/0.05 ha and 186.6 kg/0.05 ha were recorded for the two strains, with the Ain Taoujdate site achieving yields of 157.1 kg/0.05 ha and 151.1 kg/0.05 ha for each of the two strains. Additionally, further observations revealed that the Siena variety is more susceptible to rot than the Bellini variety. However, Ach1-1 and Ach1-2 strains had a significant effect on this rot, showcasing their potential to mitigate this negative issue in the Bellini variety. These promising results underscore the potential of PGPMs to enhance potato production in the Fez–Meknes region of Morocco, contributing to global food security amid climate change. Full article
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11 pages, 979 KiB  
Article
In Vitro Antiviral Potential of Cucurbitaceae Ecballium elaterium and Its Extract Containing Protease Inhibitors against Bovine Rotavirus
Microbiol. Res. 2023, 14(4), 2079-2089; https://doi.org/10.3390/microbiolres14040140 - 08 Dec 2023
Viewed by 662
Abstract
Bovine rotaviruses (BRVs) are significant causative agents of severe diarrhea in newborn calves, resulting in substantial economic losses in the livestock industry. Inhibition of bovine rotavirus using extracts prepared from a Cucurbitaceae plant, which contains trypsin protease inhibitors, might offer a potential anti-rotaviral [...] Read more.
Bovine rotaviruses (BRVs) are significant causative agents of severe diarrhea in newborn calves, resulting in substantial economic losses in the livestock industry. Inhibition of bovine rotavirus using extracts prepared from a Cucurbitaceae plant, which contains trypsin protease inhibitors, might offer a potential anti-rotaviral effect in vitro. Ecballium elaterium (E. elaterium) belongs to the Cucurbitaceae family, indigenous to the Mediterranean, contains E. elaterium trypsin isoinhibitors (EETIso), and has been used in traditional medicine. This study aimed to evaluate the in vitro efficacy of E. elaterium extract against bovine rotavirus infections. Ethanol extracts were prepared from E. elaterium seeds and fruit juice, and their non-toxic concentrations were determined using MA-104 cells. The cells were infected with bovine rotavirus in the presence of E. elaterium extract. The results demonstrated a significant decrease in the rotavirus titer in vitro upon treatment with the E. elaterium extract, suggesting its potential as a therapeutic agent against bovine rotavirus-induced diarrhea in calves. The utilization of E. elaterium extract may contribute to reduced calf mortality, lower medication costs, and improved economic value in cattle farming. Full article
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12 pages, 1208 KiB  
Article
Response of Biofortified Green Bean Plants to Colletotrichum lindemuthianum
Microbiol. Res. 2023, 14(4), 2067-2078; https://doi.org/10.3390/microbiolres14040139 - 06 Dec 2023
Viewed by 781
Abstract
Enhancing crop nutrition though biofortification with essential minerals can, in some circumstances, increase the resistance of plants to the attack by pathogens. As a result, plants activate their defense mechanisms and produce bioactive compounds (BCs) in response. To date, there has been no [...] Read more.
Enhancing crop nutrition though biofortification with essential minerals can, in some circumstances, increase the resistance of plants to the attack by pathogens. As a result, plants activate their defense mechanisms and produce bioactive compounds (BCs) in response. To date, there has been no investigation into the response of green bean plants fortified with magnesium (Mg) salts to the presence of Colletotrichum lindemuthianum. This research involved two Mg sources applied by the edaphic route. The pathogen was inoculated on green bean pods, and subsequent analysis was conducted on the accumulation of BCs, including total anthocyanins, total phenols, and total flavonoids, within both symptomatic and healthy tissues. Remarkably, the plant’s defense system was activated, as evidenced by the significantly higher concentration of anthocyanins (p ≤ 0.05) observed in the symptomatic tissues following treatments with both MgCl2 and MgSO4. Further, green bean plants treated with MgSO4 displayed notably elevated concentrations of phenols (p ≤ 0.05) in the inoculated tissues of the pods, suggesting a plausible plant defense mechanism. The levels of BCs were considerably higher in green bean pods of the biofortified plants compared to those which were nonbiofortified. However, perhaps one of the most noteworthy findings is that there were no discernible differences between biofortified and nonbiofortified treatments in stopping anthracnose in green bean pods. These results provide valuable insights contributing to a deeper understanding of this interaction. Full article
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26 pages, 4642 KiB  
Article
Novel Bioformulations with Trichoderma lixii to Improve the Growth Dynamics and Biocontrol of the Cowpea Damping-Off Disease
Microbiol. Res. 2023, 14(4), 2041-2066; https://doi.org/10.3390/microbiolres14040138 - 04 Dec 2023
Viewed by 836
Abstract
Because agricultural wastes are abundant in biologically active substances, they can be used as a substitute source to produce highly valuable products while lowering pollution levels in the environment. Therefore, we aimed at determining the best agricultural wastes to increase the biomass production [...] Read more.
Because agricultural wastes are abundant in biologically active substances, they can be used as a substitute source to produce highly valuable products while lowering pollution levels in the environment. Therefore, we aimed at determining the best agricultural wastes to increase the biomass production rate and the effectiveness of the biocontrol strain Trichoderma lixii SARS 111 in a solid-state fermentation system. The potential for its use in enhancing growth dynamics and controlling the Fusarium oxysporum NCAIM-F-00779-caused damping-off disease of cowpea plants grown in greenhouse conditions was also studied. Using a one-factor-at-a-time experiment, five cheap agricultural waste substrates (faba bean, cowpea, sweet potato, pumpkin, and cassava) were studied using the Plackett–Burman design (PBD) and the central composite design (CCD) to optimize the nutritional and growth conditions to maximize the production of Trichoderma conidia. The findings demonstrated that increasing Candida production quantitatively required the use of 3 g of sweet potato, 3 g of cassava, pH 6, 25 °C, and pre-treatment with dH2O. The shelf life and viability of T. lixii strain were measured as log10 CFU g−1 per substrate at room temperature (RT, 25 °C) at the beginning of month 0 and subsequently at 2-month intervals for 12 months. Data showed that the fungal counts increased with the use of 4 g of sweet potato + 2 g of cassava up to 7 months and then sharply decreased, lasting up to 12 months. Additionally, this bioformulation was applied to cowpea plants in a greenhouse experiment, where a significantly higher level of plant growth traits, photosynthetic pigments, antioxidant enzymes, and chemical content in the leaves, as well as lower incidence of the damping-off disease, were noted. Accordingly, it is possible to suggest 4 g of sweet potato and 2 g of cassava as a suitable bioformulation for the industrial-scale production of the T. lixii strain, which may be a potential biocontrol agent for preventing the cowpea damping-off disease caused by F. oxysporum and improving the growth dynamics. Full article
(This article belongs to the Special Issue Antifungal Agents: Treatment for Indoor Mold Exposure)
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7 pages, 1599 KiB  
Brief Report
The Detection of Circulating Cell-Free DNA for the Diagnosis of Schistosoma in Immigrants from African Countries in Italy
Microbiol. Res. 2023, 14(4), 2034-2040; https://doi.org/10.3390/microbiolres14040137 - 01 Dec 2023
Viewed by 536
Abstract
The rising migration and travel from and towards endemic areas has brought renewed concerns about many parasitic infections, including neglected tropical diseases, such as schistosomiasis. Although serology is the most widely used method for the screening of schistosomiasis in non-endemic countries, this technique [...] Read more.
The rising migration and travel from and towards endemic areas has brought renewed concerns about many parasitic infections, including neglected tropical diseases, such as schistosomiasis. Although serology is the most widely used method for the screening of schistosomiasis in non-endemic countries, this technique lacks sensitivity, especially to distinguish between past and ongoing infections. More recently, a molecular test based on the detection of Schistosoma cell-free DNA in the serum has been proposed as a diagnostic procedure for parasitosis. To test the performance of a blood PCR assay, this work investigated 102 serum samples collected from migrants coming from endemic areas by using primers specific to genomic regions of S. mansoni and S. haematobium patients. The results were then compared with the detection of specific IgG Abs with serological tests. Molecular analysis detected Schistosoma DNA in 32 patients. Among them, we characterized nine S. haematobium, 20 S. mansoni, and three coinfections. Compared with molecular assay, serological analysis detected specific antibodies against Schistosoma antigens in 52 out of 102 patients. Concordance between the two tests was found in 76 out of 102 patients (74.51%): in particular, both diagnostic tests were positive in 29 patients (28.43%) and negative in 47 (46.08%). The specificity of the molecular test was 94%. Overall, our data suggest that serological diagnosis could be combined with the molecular approach, providing the clinician with the serotyping of the parasite and useful information about the infection as well as the required further diagnostic procedures. Full article
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12 pages, 2746 KiB  
Article
Evaluation of Outer Surface Protein Vaccine Candidates of Borrelia burgdorferi for Lyme Disease
Microbiol. Res. 2023, 14(4), 2022-2033; https://doi.org/10.3390/microbiolres14040136 - 28 Nov 2023
Viewed by 606
Abstract
Lyme disease affects several hundred thousand people worldwide annually, yet there is no registered vaccine for the disease available for human use. The disease is caused by Borrelia burgdorferi sensu lato complex bacteria, which harbor numerous outer surface proteins, and many of which [...] Read more.
Lyme disease affects several hundred thousand people worldwide annually, yet there is no registered vaccine for the disease available for human use. The disease is caused by Borrelia burgdorferi sensu lato complex bacteria, which harbor numerous outer surface proteins, and many of which have been targeted for vaccine development. However, to effectively combat various Borrelia species, the target protein should ideally be conserved and located in the chromosome. In this study, we evaluated the potential of seven conservative, chromosome-encoded outer surface proteins as vaccine candidates. Unfortunately, four of the initial candidates could not be produced in E. coli. The remaining BB0028, BB0158, and BB0689 proteins were administered to mice in both the free form and as conjugates with virus-like particles (VLPs). In most cases, high antibody titers were obtained, confirming the good immunogenicity of the selected proteins. However, for BB0158 and BB0689 proteins, adverse effects were observed following the injection of free proteins, which were not observed when they were coupled to VLPs. Bactericidity tests of the obtained antibodies suggested that none of the vaccine candidates could induce the production of bactericidal antibodies. Full article
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22 pages, 8658 KiB  
Review
Colombian Fungal Diversity: Untapped Potential for Diverse Applications
Microbiol. Res. 2023, 14(4), 2000-2021; https://doi.org/10.3390/microbiolres14040135 - 28 Nov 2023
Viewed by 825
Abstract
The current list of fungi from Colombia updated in the present review contains a total of 7619 species. The Ascomycota appears as the most diverse group, with 4818 species, followed by the Basidiomycota, with 2555 species. Despite this, we presume that the actual [...] Read more.
The current list of fungi from Colombia updated in the present review contains a total of 7619 species. The Ascomycota appears as the most diverse group, with 4818 species, followed by the Basidiomycota, with 2555 species. Despite this, we presume that the actual fungal diversity in Colombia could amount to between 105,600 and 300,000 species. Fungi represent an underestimated resource, indispensable for human well-being. Even though the current knowledge on potential applications of Colombian fungi is still limited, the number of studies on areas such as natural products discovery, biological control, and food and beverages, among other biotechnological applications, are increasing. With the current review, we aim to present a comprehensive update on the fungal diversity in Colombia and its potential applications. Colombia’s native fungal biodiversity holds much potential within the country’s current social-economical context, and the future must ensure efforts to preserve both the biodiversity and the untapped resources of the fungi in Colombia, which in alignment with the Sustainable Development Goals (SDGs) might result in new bioeconomy avenues for the country. Full article
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16 pages, 5006 KiB  
Article
Characterization and Biological Activities of Yeasts Isolated from Marine Environments
Microbiol. Res. 2023, 14(4), 1984-1999; https://doi.org/10.3390/microbiolres14040134 - 23 Nov 2023
Viewed by 801
Abstract
Marine yeasts have versatile applications in the industrial, medical, and environmental fields. However, they have received little attention compared to terrestrial yeasts and filamentous fungi. In this study, a phylogenetic analysis of 11 marine-derived yeasts was conducted using internal transcribed spacers and nuclear [...] Read more.
Marine yeasts have versatile applications in the industrial, medical, and environmental fields. However, they have received little attention compared to terrestrial yeasts and filamentous fungi. In this study, a phylogenetic analysis of 11 marine-derived yeasts was conducted using internal transcribed spacers and nuclear large subunit rDNA, and their bioactivities, such as antioxidant, antibacterial, and tyrosinase inhibition activities, were investigated. The 11 marine-derived yeasts were identified to belong to seven species including Geotrichum candidum, Metschnikowia bicuspidata, Papiliotrema fonsecae, Rhodotorula mucilaginosa, Vishniacozyma carnescens, Yamadazyma olivae, and Yarrowia lipolytica, and three strains of these were candidates for new species of the genera Aureobasidium, Rhodotorula, and Vishniacozyma. Most extracts showed antioxidant activity, whereas seven strains exhibited antibacterial activities against Bacillus subtilis. Only Aureobasidium sp. US-Sd3 among the 11 isolates showed tyrosinase inhibition. Metschnikowia bicuspidata BP-Up1 and Yamadazyma olivae K2-6 showed notable radical-scavenging activity, which has not been previously reported. Moreover, Aureobasidium sp. US-Sd3 exhibited the highest antibacterial and tyrosinase inhibitory activities. These results demonstrate the potential of marine-derived yeasts as a source of bioactive compounds for improving industrial applications. Full article
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15 pages, 2034 KiB  
Article
Tannin-Tolerant Saccharomyces cerevisiae Isolated from Traditional Fermented Tea (Miang) of Northern Thailand and Its Feasible Applications
Microbiol. Res. 2023, 14(4), 1969-1983; https://doi.org/10.3390/microbiolres14040133 - 20 Nov 2023
Viewed by 656
Abstract
This study evaluated the ability of a yeast strain isolated from traditional fermented tea leaves (Camellia sinensis var. assamica), Miang from northern Thailand, to grow and produce ethanol in the presence of tannin. Among 43 Miang samples, 25 yeast isolates displayed [...] Read more.
This study evaluated the ability of a yeast strain isolated from traditional fermented tea leaves (Camellia sinensis var. assamica), Miang from northern Thailand, to grow and produce ethanol in the presence of tannin. Among 43 Miang samples, 25 yeast isolates displayed gas-forming character in the presence of 1% (w/v) tannin, but only ML1-1 and ML1-2 isolates were confirmed as ethanol-producing yeast capable of tannin tolerance. These isolates were further identified to be Pichia occidentalis and Saccharomyces cerevisiae, respectively, based on D1/D2 domain sequence analysis. S. cerevisiae ML1-2 was selected for further studies and exhibited growth at 20–35 °C, pH 4–7, and tolerance to high sugar concentrations of up to 350 g/L. Supplementation of 1% (w/v) tannin had no effect on sugar utilization and ethanol production, while delayed sugar consumption and ethanol production were observed in the reference strain S. cerevisiae TISTR 5088. However, 5 and 10% (w/v) tannin showed inhibitory effects on the growth and ethanol production of the selected yeast isolates. During the fermentation under high tannin conditions derived by mixing Java plum fruit with ground seed, S. cerevisiae ML1-2 showed significant advantages in growth and enhanced the content of ethanol, polyphenols, tannin, and flavonoids compared to S. cerevisiae TISTR 5088. This indicated its potential for high-tannin substrate-based bioconversion for the production of either fuel ethanol or functional alcoholic beverages. Full article
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13 pages, 3717 KiB  
Communication
Metagenomic Sequencing Analysis of the Effects of Acetylcysteine on the Pig Gut Microbiome
Microbiol. Res. 2023, 14(4), 1956-1968; https://doi.org/10.3390/microbiolres14040132 - 20 Nov 2023
Viewed by 773
Abstract
The gut microbiota is engaged in multiple interactions affecting host health, and gut dysbiosis can lead to many diseases. However, the effects of acetylcysteine (NAC) on the gut microbiome composition in pigs using metagenomic sequencing have not been reported. In this study, we [...] Read more.
The gut microbiota is engaged in multiple interactions affecting host health, and gut dysbiosis can lead to many diseases. However, the effects of acetylcysteine (NAC) on the gut microbiome composition in pigs using metagenomic sequencing have not been reported. In this study, we used metagenome sequencing to study the effects of NAC on the pig gut microbiome. Sequencing results showed that microbial diversity was changed after NAC treatment. Antibiotic Resistance Genes Database (ARDB) analysis demonstrated that the main genes modified were macb, tsnr, norm, bl2be-per, vansb and pbp1b in the NAC group. Our data showed that NAC could affect microbial distribution at the phylum, gene and species levels. At the species level, NAC significantly increased the abundances of Megasphaera, Lactobacillus reuteri and Megasphaeraelsdenii and reduced the abundances of Phascolarctobacterium succinatutens, Prevotellacopri and Selenomonasbovis compared with the control group. In addition, Gene Ontology (GO) analysis revealed that in the NAC group, cellular process, metabolic process and single-organism process were the dominant terms. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that RNA transport, MAPK signaling pathway, cell cycle, glycosylphosphatidylinositol (GPI)-anchor biosynthesis and VEGF signaling pathway were the dominant signaling pathways in the NAC group. In conclusion, our results suggest that NAC may modify the piglet gut microbiome composition and these findings might provide a new strategy for maintaining animal and human health in the future. Full article
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14 pages, 971 KiB  
Review
Are Gastrointestinal Microorganisms Involved in the Onset and Development of Amyloid Neurodegenerative Diseases?
Microbiol. Res. 2023, 14(4), 1942-1955; https://doi.org/10.3390/microbiolres14040131 - 20 Nov 2023
Viewed by 552
Abstract
This review discusses a few examples of specific mechanisms mediating the contribution of the GIT microbiota to the development of amyloid neurodegenerative diseases caused by the pathologic transformation of prion protein, or alpha-synuclein. The effect of the bacterial GroE chaperonin system and phage [...] Read more.
This review discusses a few examples of specific mechanisms mediating the contribution of the GIT microbiota to the development of amyloid neurodegenerative diseases caused by the pathologic transformation of prion protein, or alpha-synuclein. The effect of the bacterial GroE chaperonin system and phage chaperonins (single-ring OBP and double-ring EL) on prion protein transformation has been described. A number of studies have shown that chaperonins stimulate the formation of cytotoxic amyloid forms of prion protein in an ATP-dependent manner. Moreover, it was found that E. coli cell lysates have a similar effect on prion protein, and the efficiency of amyloid transformation correlates with the content of GroE in cells. Data on the influence of some metabolites synthesized by gut microorganisms on the onset of synucleinopathies, such as Parkinson’s disease, is provided. In particular, the induction of amyloid transformation of alpha-synuclein from intestinal epithelial cells with subsequent prion-like formation of its pathologic forms in nervous tissues featuring microbiota metabolites is described. Possible mechanisms of microbiota influence on the occurrence and development of amyloid neurodegenerative diseases are considered. Full article
(This article belongs to the Special Issue Current Progress in Prion Research)
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36 pages, 30809 KiB  
Article
Natural Products from Marine Actinomycete Genus Salinispora Might Inhibit 3CLpro and PLpro Proteins of SARS-CoV-2: An In Silico Evidence
Microbiol. Res. 2023, 14(4), 1907-1941; https://doi.org/10.3390/microbiolres14040130 - 15 Nov 2023
Viewed by 808
Abstract
Among the oldest marine species on the planet, the genus Salinispora is often encountered inhabiting sediments and other marine creatures in tropical and subtropical marine settings. This bacterial genus produces a plethora of natural products. The purpose of this study was to examine [...] Read more.
Among the oldest marine species on the planet, the genus Salinispora is often encountered inhabiting sediments and other marine creatures in tropical and subtropical marine settings. This bacterial genus produces a plethora of natural products. The purpose of this study was to examine the potential for salinispora-based natural products (NPs) to combat the SARS-CoV-2 virus. The RCSB PDB was used to obtain the crystal structures of proteins 3CLpro and PLpro. All 125 NPs were obtained from online databases. Using Autodock Vina software v1.2.0 the molecular docking process was carried out after the proteins and ligands were prepared. Assessments of binding affinities and interacting amino acids were rigorously examined prior to MD simulations. The docking experiments revealed 35 NPs in total for both 3CLpro and PLpro, with high docking scores ranging from −8.0 kcal/mol to −9.0 kcal/mol. However, a thorough binding residue analyses of all docked complexes filtered nine NPs showing strong interactions with HIS: 41 and CYS: 145 of 3CLpro. Whereas, for PLpro, merely six NPs presented good interactions with residues CYS: 111, HIS: 272, and ASP: 286. Further research was conducted on residue–residue and ligand–residue interactions in both the filtered docked complexes and the Apo-protein structures using the Protein Contacts Atlas website. All complexes were found to be stable in CABS-flex 2.0 MD simulations conducted at various time frames (50, 125, 500, and 1000 cycles). In conclusion, salinaphthoquinone B appears to be the most promising metabolite, based on favorable amino acid interactions forming stable confirmations towards 3CLpro and PLpro enzymes, acting as a dual inhibitor. Full article
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13 pages, 1874 KiB  
Article
Poly(3-Hydroxybutyrate) Biosynthesis from [U-13C6]D-Glucose by Ralstonia eutropha NCIMB 11599 and Recombinant Escherichia coli
Microbiol. Res. 2023, 14(4), 1894-1906; https://doi.org/10.3390/microbiolres14040129 - 12 Nov 2023
Viewed by 1340
Abstract
The use of stable isotope-labeled polymers in in situ biodegradation tests provides detailed information on the degradation process. As isotope-labeled raw chemicals are generally expensive, it is desirable to prepare polymer samples with high production yields and high isotope-labeling ratios. The biodegradable plastic [...] Read more.
The use of stable isotope-labeled polymers in in situ biodegradation tests provides detailed information on the degradation process. As isotope-labeled raw chemicals are generally expensive, it is desirable to prepare polymer samples with high production yields and high isotope-labeling ratios. The biodegradable plastic poly[(R)-3-hydroxybutyrate)] (P(3HB)) is produced by microorganisms. In this study, to produce carbon 13 (13C)-labeled P(3HB) from [U-13C6]D-glucose (13C-glucose), the culture conditions needed for high production yields and high 13C-labeling ratios were investigated using Ralstonia eutropha NCIMB 11599 and recombinant Escherichia coli JM109. We found that over 10 g/L of P(3HB) could be obtained when these microorganisms were cultured in Luria-Bertani (LB3) medium containing 3 g/L NaCl and 40 g/L 13C-glucose, while 1.4–4.7 g/L of P(3HB) was obtained when a mineral salt (MS) medium containing 20 g/L 13C-glucose was used. The 13C-labeling ratio of P(3HB) was determined by 1H nuclear magnetic resonance and gas chromatography-mass spectrometry (GC-MS), and both analytical methods yielded nearly identical results. High 13C-labeling ratios (97.6 atom% by GC-MS) were observed in the MS medium, whereas low 13C-labeling ratios (88.8–94.4 atom% by GC-MS) were observed in the LB3 medium. Isotope effects were observed for the P(3HB) content in cells cultured in the LB3 medium and the polydispersity of P(3HB). Full article
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15 pages, 2654 KiB  
Article
Green Synthesis of Nickel Nanoparticles Using Salvadora persica and Their Application in Antimicrobial Activity against Oral Microbes
Microbiol. Res. 2023, 14(4), 1879-1893; https://doi.org/10.3390/microbiolres14040128 - 10 Nov 2023
Viewed by 958
Abstract
The current study evaluated the biogenic synthesis of nickel oxide nanoparticles (SP-NiONPs) from the root extract of (Salvadora persicaS. persica and their biological properties. The nanoparticles were characterized using spectroscopic and microscopic techniques and then evaluated for their antimicrobial properties [...] Read more.
The current study evaluated the biogenic synthesis of nickel oxide nanoparticles (SP-NiONPs) from the root extract of (Salvadora persicaS. persica and their biological properties. The nanoparticles were characterized using spectroscopic and microscopic techniques and then evaluated for their antimicrobial properties against 10 oral pathogens. The ultraviolet-visible (UV–Vis) spectra exhibited a distinctive resonance spectrum at 334 nm for the SP-NiONPs produced from S. persica. The fourier transform infrared (FTIR) analysis revealed the presence of functional groups of biomolecules of S. persica that served as reducing and capping agents of the SP-NiONPs. The scanning electron microscope (SEM) and transmission electron microscopy (TEM) analyses showed that the nanoparticles were spherical-shaped, tightly packed, and ranged in size from 18.20 nm to 45.12 nm. The energy dispersive x-ray (EDX) analysis confirmed 69.9% of the nickel (Ni) content by weight, and the X-ray diffraction (XRD) results showed the face-centered cubic (FCC) crystalline structure of the formed SP-NiONPs. The antioxidant activity of the SP-NiONPs exhibited a dose-dependent profile with an IC50 value of 51.45 ± 0.65 and a 54.13 ± 0.98 DPPH and ABTS•+ radical scavenging activity, respectively. The SP-NiONPs showed an antibacterial activity against all the test strains; however, E. cloacae was found to be the most sensitive strain, with an inhibition zone of 31 ± 0.50 mm. The SEM image of the E. cloacae cells treated with SP-NiONPs showed irregular shapes and ruptured, destroyed cell membranes. Our findings revealed that SP-NiONPs could be used as excellent antibacterial agents against oral pathogens. Full article
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17 pages, 624 KiB  
Review
The Interaction between the Oral Microbiome and Systemic Diseases: A Narrative Review
Microbiol. Res. 2023, 14(4), 1862-1878; https://doi.org/10.3390/microbiolres14040127 - 09 Nov 2023
Cited by 1 | Viewed by 1317
Abstract
Background: The human being is defined as a ‘superorganism’ since it is made up of its own cells and microorganisms that reside inside and outside the human body. Commensal microorganisms, which are even ten times more numerous than the cells present in [...] Read more.
Background: The human being is defined as a ‘superorganism’ since it is made up of its own cells and microorganisms that reside inside and outside the human body. Commensal microorganisms, which are even ten times more numerous than the cells present in the body, perform very important functions for the host, as they contribute to the health of the host, resist pathogens, maintain homeostasis, and modulate the immune system. In the mouth, there are different types of microorganisms, such as viruses, mycoplasmas, bacteria, archaea, fungi, and protozoa, often organized in communities. The aim of this umbrella review is to evaluate if there is a connection between the oral microbiome and systematic diseases. Methodology: A literature search was conducted through PubMed/MEDLINE, the COCHRANE library, Scopus, and Web of Science databases without any restrictions. Because of the large number of articles included and the wide range of methods and results among the studies found, it was not possible to report the results in the form of a systematic review or meta-analysis. Therefore, a narrative review was conducted. We obtained 73.931 results, of which 3593 passed the English language filter. After the screening of the titles and abstracts, non-topic entries were excluded, but most articles obtained concerned interactions between the oral microbiome and systemic diseases. Discussion: A description of the normal microbial flora was present in the oral cavity both in physiological conditions and in local pathological conditions and in the most widespread systemic pathologies. Furthermore, the therapeutic precautions that the clinician can follow in order to intervene on the change in the microbiome have been described. Conclusions: This review highlights what are the intercorrelations of the oral microbiota in healthy subjects and in subjects in pathological conditions. According to several recent studies, there is a clear correlation between dysbiosis of the oral microbiota and diseases such as diabetes, cardiovascular diseases, chronic inflammatory diseases, and neurodegenerative diseases. Full article
(This article belongs to the Special Issue Oral Microorganisms and Systemic Diseases)
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19 pages, 5016 KiB  
Article
Model of Pulmonary Co-Infection of Aspergillus and Pseudomonas in Immunocompetent Mice
Microbiol. Res. 2023, 14(4), 1843-1861; https://doi.org/10.3390/microbiolres14040126 - 08 Nov 2023
Viewed by 601
Abstract
Co-infection with Pseudomonas (Pa) and Aspergillus (Af) commonly occurs in the airways of immune-compromised patients or in cystic fibrosis and frequently results in more severe outcomes than mono-infection. We affixed both pathogens to agar beads, separately (Af beads, Pa beads) or on the [...] Read more.
Co-infection with Pseudomonas (Pa) and Aspergillus (Af) commonly occurs in the airways of immune-compromised patients or in cystic fibrosis and frequently results in more severe outcomes than mono-infection. We affixed both pathogens to agar beads, separately (Af beads, Pa beads) or on the same bead (AfPa beads) and infected immunocompetent mice, an in vivo Af-Pa interaction model. Endotracheal administration was superior to intranasal, allowing larger beads to be administered resulting in longer lung residence. The CFU of the Af beads, diameter 150–250 µm, were detectable for ≤21 days. Af-bead-infected mice cleared the Af infection more than mice infected with AfPa beads, but Af clearance was the same with a combination of beads (Af beads + Pa beads). Pa-infected mice had more Pa clearance in the presence of Af than with Pa beads alone. In vitro studies supported our conclusion that the close proximity of Af and Pa (on AfPa beads) was disadvantageous for Af, whereas a larger distance (Af + Pa beads) was not. We demonstrated that the interaction between Pseudomonas and Aspergillus during co-infection can be studied in immunocompetent mice. The mutual inhibition of Af and Pa in vivo appears to be dependent on their proximity. We review the literature relating to animal models of infection with Af, Pa, or both. Full article
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9 pages, 803 KiB  
Communication
The Respiratory Way without Microbial Growth of Paracoccus denitrificans
Microbiol. Res. 2023, 14(4), 1834-1842; https://doi.org/10.3390/microbiolres14040125 - 06 Nov 2023
Viewed by 853
Abstract
This study elucidates the effects of Carbon/Nitrogen (C/N) ratios on the respiratory behavior of Paracoccus denitrificans PD1222, a microorganism noted for its metabolic adaptability. We explored its ability to undergo dissimilative denitrification, a less understood process where energy is harnessed from nutrient consumption [...] Read more.
This study elucidates the effects of Carbon/Nitrogen (C/N) ratios on the respiratory behavior of Paracoccus denitrificans PD1222, a microorganism noted for its metabolic adaptability. We explored its ability to undergo dissimilative denitrification, a less understood process where energy is harnessed from nutrient consumption without resultant growth. By manipulating the C/N ratios and available nitrogen sources in our experimental design, we were able to demonstrate significant shifts in P. denitrificans metabolic behavior. At a C/N ratio of 1.34, with nitrate as the sole nitrogen source, dissimilative denitrification occurred with no observable increase in biomass. Succinate, the provided carbon source, was quickly metabolized without contributing to cell growth. Our results contribute to the understanding of environmental microbiology, specifically denitrification processes, and indicate P. denitrificans’s potential for wastewater treatment scenarios, where pollutant consumption without biomass proliferation is desired. Full article
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14 pages, 1743 KiB  
Article
Identification, Viability, and Membrane Potential during the Cryopreservation of Autochthonous Lactic-Acid Bacteria Isolated from Artisanal Adobera Cheese from Los Altos de Jalisco
Microbiol. Res. 2023, 14(4), 1820-1833; https://doi.org/10.3390/microbiolres14040124 - 04 Nov 2023
Viewed by 863
Abstract
Lactic acid bacteria (LAB) comprise a group of microorganisms responsible for developing the sensory and chemical characteristics of several foods and fermented products, particularly cheese. For this reason, after isolation and identification of LAB, validated protocols and procedures for their long-term preservation without [...] Read more.
Lactic acid bacteria (LAB) comprise a group of microorganisms responsible for developing the sensory and chemical characteristics of several foods and fermented products, particularly cheese. For this reason, after isolation and identification of LAB, validated protocols and procedures for their long-term preservation without compromising its integrity and technological properties, as well as methodologies aiming to assess their viability and integrity are paramount. This study aimed to isolate and identify autochthonous LAB from artisanal Adobera cheese and determine the effect of LAB cryopreservation with thioglycolate broth and glycerol on their viability, membrane integrity, and kinetics. Sixteen LAB were isolated and genetically identified from artisanal cheese samples; eleven of those strains were selected (genus Lactobacillus, Leuconostoc, Streptococcus, and Lactococcus) and included in the cryo-preservation assay. The initial average concentration of the bacterial suspensions was 6.89 log10 CFU mL−1; increasing to 8.9 log10 CFU mL−1 21 days later and slightly reduced at day 42 post-preservation (losses below one logarithm). About 77% of the cells maintained their membrane potential 180 days after their preservation and showed normal Kinetic parameters, maintaining normal adaptation times (Lag phase) and Log phases (9 h average), before reaching the stationary phase. The proposed protocol constitutes a viable alternative to the long-term preservation of different LAB genera because it keeps their viability and integrity. Using flow cytometry allowed the enumeration of viable LAB and provide evidence of the integrity of their membrane. Full article
(This article belongs to the Collection Microbiology and Technology of Fermented Foods)
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32 pages, 2239 KiB  
Article
Preliminary Data on Escherichia coli, Yersinia enterocolitica, and Other Bacteria, as Well as Absent African Swine Fever Virus in the Gut Microbiota of Wild Mice and Voles from Bulgaria
Microbiol. Res. 2023, 14(4), 1788-1819; https://doi.org/10.3390/microbiolres14040123 - 04 Nov 2023
Viewed by 995
Abstract
Small mammals are bioindicator organisms, and, through their gut microbiota (GM), could be carriers of pathogens and resistant bacteria. Also, wild GM composition has been suggested to have large implications for conservation efforts. Seventeen bacterial species were obtained from intestinal samples of Bulgarian [...] Read more.
Small mammals are bioindicator organisms, and, through their gut microbiota (GM), could be carriers of pathogens and resistant bacteria. Also, wild GM composition has been suggested to have large implications for conservation efforts. Seventeen bacterial species were obtained from intestinal samples of Bulgarian yellow-necked mice (Apodemus flavicollis) and bank voles (Myodes glareolus) via classic microbiological cultivation and biochemical identification. Twelve Gram-negative—Escherichia coli, Yersinia enterocolitica, Yersinia kristensenii, Hafnia alvei, Serratia liquefaciens, Serratia marcescens, Serratia proteamaculans, Pseudescherichia vulneris, Klebsiella pneumoniae ssp. ozaenae, Enterobacter cloacea, Pantoea agglomerans, Pseudomonas fluorescens group—and five Gram-positive bacteria, Enterococcus faecium, Enterococcus faecalis, Enterococcus hirae, Bacillus thuringiensis, and Lysinibacillus sphaericus, were discovered. Enterobacteriaceae was the most abundant family. The isolates belonged to one of the major reported taxa in rodents, Firmicutes (the Gram-positive species) and to the less abundant, but still among the first, phyla, Proteobacteria (the Gram-negative strains). We did not find any members of the other major phylum, Bacteroidetes, likely due to lack of metagenomic techniques. E. coli and Y. enterocolitica were confirmed with polymerase chain reaction. Almost all strains had pathogenic potential, but the good condition of the test animals suggests their commensal role. The Y. enterocolitica strains did not have the ail pathogenicity gene. There was high prevalence of multi-drug resistance (MDR), but for the expected species with high level of intrinsic resistance, such as the enterococci and S. marcescens. E. coli and some other species had very low antimicrobial resistance (AMR), in line with other studies of wild rodents. Many of the strains had biotechnological potential; e.g., B. thuringiensis is the most used biological insecticide, with its proteins incorporated into the Bt genetically modified maize. The GM of the tested wild mice and voles from Bulgaria proved to be a source of bacterial diversity; many of the strains were promising in terms of biotechnology, and, in addition, the samples did not contain the African swine fever virus. Full article
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14 pages, 1898 KiB  
Communication
Geobacter grbiciae—A New Electron Donor in the Formation of Co-Cultures via Direct Interspecies Electron Transfer
Microbiol. Res. 2023, 14(4), 1774-1787; https://doi.org/10.3390/microbiolres14040122 - 02 Nov 2023
Viewed by 742
Abstract
Geobacter grbiciae can grow via coupling oxidation of ethanol to the reduction of various forms of soluble Fe(III) and poorly crystalline Fe(III) oxide, suggesting that G. grbiciae can act as an electron-donor microbe for forming co-cultures through direct interspecies electron transfer (DIET). In [...] Read more.
Geobacter grbiciae can grow via coupling oxidation of ethanol to the reduction of various forms of soluble Fe(III) and poorly crystalline Fe(III) oxide, suggesting that G. grbiciae can act as an electron-donor microbe for forming co-cultures through direct interspecies electron transfer (DIET). In this report, potential co-cultures through DIET of G. grbiciae and Methanosarcina barkeri 800, G. sulfurreducens Δhyb, or Methanospirillum hungatei, as electron-acceptor microbes, were examined. Co-cultures of G. grbiciae and G. sulfurreducens Δhyb were performed with ethanol as the sole electron-donor substance and fumarate as the electron-acceptor substance in the presence of granular activated carbon (GAC), magnetite, or polyester felt. The conditions for co-culturing G. grbiciae and M. barkeri 800 (or M. hungatei) were the same as those for G. grbiciae and G. sulfurreducens Δhyb, except fumarate was absent and different cultivation temperatures were used. All co-cultures were anaerobically cultivated. Samples were regularly withdrawn from the co-cultures to monitor methane, fumarate, and succinate via gas or high-performance liquid chromatography. G. grbiciae formed functional co-cultures with M. barkeri 800 in the presence of GAC or magnetite. No co-culture of G. grbiciae with the H2/formate-utilizing methanogen M. hungatei was observed. Additionally, G. grbiciae formed functional co-cultures with H2/formate-un-utilizing G. sulfurreducens Δhyb without the GAC or magnetite supplement. These findings indicate electron transfer between G. grbiciae and M. barkeri 800/G. sulfurreducens Δhyb is via DIET rather than H2/formate, confirming that G. grbiciae acts as an electron-donor microbe. Although the co-cultures of G. grbiciae and M. barkeri 800 syntrophically converted ethanol to methane through DIET, the conversion of propionate or butyrate to methane was not observed. These findings expand the range of microbes that can act as electron donors for interaction with other microbes through DIET. However, propionate and butyrate metabolism through DIET in mixed microbial communities with methane as a product requires further analysis. This study provides a framework for finding new electron-donor microbes. Full article
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10 pages, 750 KiB  
Communication
Antibiotic-Resistant Bacteria in Environmental Water Sources from Southern Chile: A Potential Threat to Human Health
Microbiol. Res. 2023, 14(4), 1764-1773; https://doi.org/10.3390/microbiolres14040121 - 01 Nov 2023
Viewed by 833
Abstract
Antimicrobial resistance (AMR) is a critical global issue affecting public and animal health. The overuse of antibiotics in human health, animal production, agriculture, and aquaculture has led to the selection of antibiotic-resistant strains, particularly in Gram-negative bacteria. Mutations and horizontal gene transfer play [...] Read more.
Antimicrobial resistance (AMR) is a critical global issue affecting public and animal health. The overuse of antibiotics in human health, animal production, agriculture, and aquaculture has led to the selection of antibiotic-resistant strains, particularly in Gram-negative bacteria. Mutations and horizontal gene transfer play a significant role in the development of antimicrobial resistance, leading to the reduced efficacy of current antibiotics. Today, AMR in bacteria and antibiotic-resistance genes (ARGs) are increasingly recognized in multiple environmental sources, including recreational and irrigation waters. This study aims to identify Gram-negative bacteria from surface aquatic reservoirs in southern Chile and assess their susceptibility to clinically relevant antibiotics. Water samples were collected from four lakes, five rivers, one waterfall, and one watershed in southern Chile to isolate environmental Gram-negative bacilli (GNB). API-20E and MALDI–TOF were employed for bacterial identification. Kirby–Bauer disc diffusion tests and multiplex PCR were performed to determine their susceptibility profile. A total of 26 GNB strains were isolated from environmental water samples, predominantly belonging to the Pseudomonas (n = 9) and Acinetobacter (n = 7) genera. Among these strains, 96.2% were resistant to ampicillin and cefazoline, while 26.9% and 34.6% showed resistance to ceftazidime and cefepime, respectively. Additionally, 38.5% exhibited resistance to colistin. Two Enterobacter cloacae strains obtained from Cachapoal River (sixth region) and Villarrica Lake (ninth region), respectively, presented a multidrug-resistant (MDR) phenotype and carried at least two extended-spectrum β-lactamase (ESBL) genes. Thus, antibiotic-resistant GNB and ARGs were found in natural water reservoirs, raising concerns about the dissemination of resistance determinants among potentially pathogenic bacteria in environmental microbial communities. Full article
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13 pages, 7176 KiB  
Review
Phaeohyphomycosis: A Review
Microbiol. Res. 2023, 14(4), 1751-1763; https://doi.org/10.3390/microbiolres14040120 - 31 Oct 2023
Viewed by 804
Abstract
Phaeohyphomycosis, a worldwide fungal infection, refers to uncommon superficial, subcutaneous, or systemic infections caused by melanized fungi. Currently, about 70 genera and 150 species have been described. It can be confirmed by mycological, histopathological, or molecular methods. Treatment can be performed by surgery [...] Read more.
Phaeohyphomycosis, a worldwide fungal infection, refers to uncommon superficial, subcutaneous, or systemic infections caused by melanized fungi. Currently, about 70 genera and 150 species have been described. It can be confirmed by mycological, histopathological, or molecular methods. Treatment can be performed by surgery or systemic antifungals. Full article
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15 pages, 1621 KiB  
Review
Exploring the Variability in Antibacterial Testing of Resin Dental Composites among Investigators: A Narrative Review
Microbiol. Res. 2023, 14(4), 1736-1750; https://doi.org/10.3390/microbiolres14040119 - 31 Oct 2023
Viewed by 604
Abstract
Caries is a common dental problem brought on by factors like excessive sugar consumption, poor oral hygiene, and the presence of microorganisms in the mouth. This dental pathology is treated with a variety of filling materials, including tooth-colored direct resin dental composite (RDC), [...] Read more.
Caries is a common dental problem brought on by factors like excessive sugar consumption, poor oral hygiene, and the presence of microorganisms in the mouth. This dental pathology is treated with a variety of filling materials, including tooth-colored direct resin dental composite (RDC), glass ionomer cement (GIC), and dental amalgam (also known as silver filling). RDC is the most preferred filling material in dental clinics due to its excellent esthetics and minimal tooth preparation, making it the need of the modern era. However, antimicrobial agents were added to this material in order to enhance its ability to prevent secondary caries. The antibacterial activity of RDC has been tested using a variety of methods, but testing protocols have been found to vary. Thusly, the point of this article is to examine the disparity in the strategy involved by specialists for testing the antibacterial properties of RDCs. Full article
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16 pages, 5397 KiB  
Article
In Vitro Cytotoxicity and Hemolysis Effect of Poly-Gamma-Glutamic Acid Nano-Polymer Biosynthesized Using Some Isolates of Bacillus spp.
Microbiol. Res. 2023, 14(4), 1720-1735; https://doi.org/10.3390/microbiolres14040118 - 29 Oct 2023
Cited by 1 | Viewed by 857
Abstract
Natural polymers have good biological, biocompatible properties and a low degradation rate, so they can be used in medical applications. This study demonstrates an optimized biosynthesis for poly-gamma-glutamic acid nano-polymer (ɣ-PGA NP) using three bacterial isolates encoded as B4, B5, and B6. The [...] Read more.
Natural polymers have good biological, biocompatible properties and a low degradation rate, so they can be used in medical applications. This study demonstrates an optimized biosynthesis for poly-gamma-glutamic acid nano-polymer (ɣ-PGA NP) using three bacterial isolates encoded as B4, B5, and B6. The 16S rRNA gene sequence of the isolates showed 98.5, 99, and 99.8% similarity with Bacillus sp., with accession numbers MZ976778, MZ976779, and MZ956153, respectively. The optimal conditions of the biosynthesis were 35 °C, followed by incubation for 30 h, 7 pH, 0.7 O.D600 of bacterial broth, carbon sources of glutamic acid and glucose, and ammonium sulfate as the nitrogen source. Biosynthesized ɣ-PGA NPs were characterized using X-ray diffraction (XRD), Zeta sizer, Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), and nuclear magnetic resonance (1HNMR). The TEM study showed the formation of oval-shaped ɣ-PGA NPs with sizes 31.75–32.69 nm, 18.63–21.66 nm, and 37.57–39.22 nm for B4, B5, and B6, respectively. XRD, FT-IR, and 1HNMR confirmed the purity of the polymer. The hemolysis rates of the biosynthesized ɣ-PGA NPs were below the acceptable value. Moreover, the cytotoxicity test conducted using an MTT assay on peripheral blood mononuclear cells (PBMCs) revealed no significant effect on the cell viability within a dose range of up to 512 μg/mL. Full article
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18 pages, 2268 KiB  
Article
Short-Term PE Generation Processes in the Soils of a Farmer Plots Network in the Madagascar Highlands: Actors and Drivers
Microbiol. Res. 2023, 14(4), 1702-1719; https://doi.org/10.3390/microbiolres14040117 - 27 Oct 2023
Viewed by 566
Abstract
Carbon sequestration in agricultural soils, through the accumulation of high-quality organic matter, represents great potential to mitigate climate change and simultaneously improve soil fertility. Such a challenge is particularly important and relevant in developing tropical countries like Madagascar, where soil carbon storage is [...] Read more.
Carbon sequestration in agricultural soils, through the accumulation of high-quality organic matter, represents great potential to mitigate climate change and simultaneously improve soil fertility. Such a challenge is particularly important and relevant in developing tropical countries like Madagascar, where soil carbon storage is vulnerable to climatic variations and where fertilization is generally applied through amendments in organic matter of various origins. The priming effect (PE) is considered here as the stimulation of the mineralization of soil organic matter (SOM) by a supply of fresh organic matter (FOM). PE results from different microbial processes driven by specific biotic and abiotic parameters. Depending on the processes involved, it has been suggested that PE could either counteract SOM accumulation or promote it. The objective of the present study was to explore the relationships between certain agricultural practices (type of crop, quality of fertilization, association with trees), the potential intensity of PE, as well as several abiotic (texture, quantity and quality SOM, nutrient enrichment) a1nd biotic (biomass and phylogenetic composition of microbial communities) factors which have been proposed in the literature as specific determinants of the different PE generation mechanisms. The soils for this study come from a network of farms in a commune in the Highlands of Madagascar. The PE, generated by a supply of 13C-enriched wheat straw, could not directly correlate with agricultural treatments. However, several indirect correlations could be found via several specific abiotic and microbial determinants that are discussed in terms of soil fertility restoration. Full article
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15 pages, 2630 KiB  
Article
Evaluation of Predicted siRNA as an Antiviral against MERS-CoV Targeting the Membrane Gene in the Vero Cell Line
Microbiol. Res. 2023, 14(4), 1687-1701; https://doi.org/10.3390/microbiolres14040116 - 17 Oct 2023
Viewed by 871
Abstract
The Middle East respiratory syndrome coronavirus (MERS-CoV) was first isolated from a patient with acute pneumonia and renal failure in Saudi Arabia in 2012. By July 2023, MERS-CoV had resulted in 2605 human cases worldwide, causing a fatality rate of 36%, with 90.2% [...] Read more.
The Middle East respiratory syndrome coronavirus (MERS-CoV) was first isolated from a patient with acute pneumonia and renal failure in Saudi Arabia in 2012. By July 2023, MERS-CoV had resulted in 2605 human cases worldwide, causing a fatality rate of 36%, with 90.2% of cases being located in the Arabian Peninsula. The dromedary camel (Camelus dromedarius) is presumed to be an intermediate host for viral transmission to humans. So far, no prophylactic vaccines or effective antiviral treatments have been approved for MERS-CoV. RNA silencing is a novel approach for treating several diseases. A web-based bioinformatics tool (i-Score Designer) with integrative computational methods was used to predict and evaluate the designed siRNAs. This approach enabled the targeting of a highly conserved region of the MERS-CoV membrane (M) gene to inhibit virus replication. siRNA-M1, -M2, and -M3 were selected as the best of 559 designed siRNA candidates for an in vitro validation based on 2nd generation algorithm scoring, thermodynamic properties, off-target filtration, position-specific nucleotide preferences, and a free immune-stimulatory motifs. siRNAs were evaluated in Vero cells for their cytotoxicity and antiviral efficacy in vitro. Our results showed that the predicted siRNAs had no apparent cytotoxicity observed in Vero cells. The obtained results from the plaque reduction assay and RT-qPCR indicated that siRNA-M3 was the best candidate to inhibit MERS-CoV replication with a defined concentration of 400 picoMolar (pM). The computational methods used, and the in vitro evaluation, may provide an insight for a new antiviral strategy against MERS-CoV, a further in vivo study will nevertheless be required. Full article
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