Advances in the Discovery of Novel Antimicrobial Agents in Nature and Their Applications

A special issue of Antibiotics (ISSN 2079-6382).

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 20378

Special Issue Editors

Faculty of Technology, University of Novi Sad, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia
Interests: ecology of microorganisms; food safety; antimicrobials; natural compounds; biodegradation and biodeterioration
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Guest Editor
Faculty of Technology Novi Sad, Department of Biotechnology, University of Novi Sad, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia
Interests: antimicrobial substance; alternative crops; food microbiology; antimicrobial activity; biowaste; bioactive compounds; natural pigments; antioxidant acitivity; food; antioxidants; encapsulation; plant extract; bioactivity; HPLC; antimicrobials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The inappropriate use of antibiotics and the inadequate control of human infections have led to emergence of resistant strains that are a major threat to public health and global economy. Therefore, seeking for a solution to this problem and replacements for antibiotics in nature has become imperative. Following this worldwide trend, this Special Issue is dedicated to the discovery of novel natural antimicrobial agents and the investigation of their mechanisms of action (targeting new proteins, inhibitors of virulence factors, nanoparticles, antisense oligonucleotides, etc.). This Special Issue also welcomes the submission of manuscripts dealing with common applications of natural antimicrobial agents, such as in the food and pharmaceutical industries and in smart packaging. We also welcome investigations on new and alternative applications, for instance the use of essential oils in the protection of cultural heritage.

Dr. Ana Tomić
Dr. Olja Lj Šovljanski
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Antibiotics is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • antimicrobials
  • essential oils
  • application
  • phytochemicals
  • natural compounds

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Published Papers (9 papers)

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Research

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17 pages, 1166 KiB  
Article
Towards a Greener Approach for Biomass Valorization: Integration of Supercritical Fluid and Deep Eutectic Solvents
by Jelena Vladić, Martina Jakovljević Kovač, Valentina Pavić, Stela Jokić, Siniša Simić, Alexandre Paiva, Igor Jerković and Ana Rita Duarte
Antibiotics 2023, 12(6), 1031; https://doi.org/10.3390/antibiotics12061031 - 08 Jun 2023
Cited by 3 | Viewed by 1426
Abstract
A green and sustainable procedure for obtaining Lavandula stoechas extracts with antioxidant and antimicrobial properties was investigated. Green solvents, supercritical CO2, and natural deep eutectic solvents (NADES) together with ultrasound-assisted extraction were used for the sequential extraction of terpene and polyphenols [...] Read more.
A green and sustainable procedure for obtaining Lavandula stoechas extracts with antioxidant and antimicrobial properties was investigated. Green solvents, supercritical CO2, and natural deep eutectic solvents (NADES) together with ultrasound-assisted extraction were used for the sequential extraction of terpene and polyphenols fractions. After the CO2 extraction of the terpene fraction, the residue material was used in an extraction with different NADES (betaine-ethylene glycol (Bet:EG), betaine-glycerol (Bet:Gly), and glycerol-glucose (Gly:Glu)), intensified with an ultrasound-assisted method (at 30 and 60 °C). In the CO2 extract, the major group of components belonged to oxygenated monoterpenes, while the highest polyphenol content with the dominant rutin (438.93 ± 4.60 µg/mL) was determined in Bet:EG extracts (60 °C). Bet:EG extracts also exhibited the most potent antioxidant activity according to DPPH, ABTS, and FRAP assays. Moreover, Bet:EG extracts showed significant inhibitory activity against Gram-positive and Gram-negative bacteria, with minimum inhibitory activity of 0.781–3.125 and 1.563–6.250 mg·mL−1, respectively. By comparing the polyphenolic content and antioxidant and antimicrobial activities of Bet:EG extracts with extracts obtained with conventional solvents (water and ethanol), the superiority of NADES was determined. The established environmentally friendly procedure unifies the requirements of green and sustainable development and modern pharmacognosy because it combines the use of safe alternative solvents, the absence of solvent waste generation, more rational use of resources, and the attainment of safe and quality extracts. Full article
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15 pages, 1921 KiB  
Article
Artificial Neural Network Prediction of Antiadhesion and Antibiofilm-Forming Effects of Antimicrobial Active Mushroom Extracts on Food-Borne Pathogens
by Jovana Vunduk, Anita Klaus, Vesna Lazić, Maja Kozarski, Danka Radić, Olja Šovljanski and Lato Pezo
Antibiotics 2023, 12(3), 627; https://doi.org/10.3390/antibiotics12030627 - 22 Mar 2023
Cited by 2 | Viewed by 1344
Abstract
The problem of microbial biofilms has come to the fore alongside food, pharmaceutical, and healthcare industrialization. The development of new antibiofilm products has become urgent, but it includes bioprospecting and is time and money-consuming. Contemporary efforts are directed at the pursuit of effective [...] Read more.
The problem of microbial biofilms has come to the fore alongside food, pharmaceutical, and healthcare industrialization. The development of new antibiofilm products has become urgent, but it includes bioprospecting and is time and money-consuming. Contemporary efforts are directed at the pursuit of effective compounds of natural origin, also known as “green” agents. Mushrooms appear to be a possible new source of antibiofilm compounds, as has been demonstrated recently. The existing modeling methods are directed toward predicting bacterial biofilm formation, not in the presence of antibiofilm materials. Moreover, the modeling is almost exclusively targeted at biofilms in healthcare, while modeling related to the food industry remains under-researched. The present study applied an Artificial Neural Network (ANN) model to analyze the anti-adhesion and anti-biofilm-forming effects of 40 extracts from 20 mushroom species against two very important food-borne bacterial species for food and food-related industries—Listeria monocytogenes and Salmonella enteritidis. The models developed in this study exhibited high prediction quality, as indicated by high r2 values during the training cycle. The best fit between the modeled and measured values was observed for the inhibition of adhesion. This study provides a valuable contribution to the field, supporting industrial settings during the initial stage of biofilm formation, when these communities are the most vulnerable, and promoting innovative and improved safety management. Full article
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14 pages, 1041 KiB  
Article
Antibacterial Activity of Selected Essential Oils against Foodborne Pathogens and Their Application in Fresh Turkey Sausages
by Branislav Šojić, Predrag Ikonić, Sunčica Kocić-Tanackov, Tatjana Peulić, Nemanja Teslić, Miloš Županjac, Ivana Lončarević, Zoran Zeković, Milica Popović, Stefan Vidaković and Branimir Pavlić
Antibiotics 2023, 12(1), 182; https://doi.org/10.3390/antibiotics12010182 - 16 Jan 2023
Cited by 8 | Viewed by 2219
Abstract
Essential oils (EOs) isolated from different plant materials, namely Origanum majorana L., Satureja hortensis L., and Satureja montana L. (OMEO, SHEO, and SMEO, respectively), were used in fresh turkey sausage processing. The chemical composition and in vitro antimicrobial potential of selected EOs and [...] Read more.
Essential oils (EOs) isolated from different plant materials, namely Origanum majorana L., Satureja hortensis L., and Satureja montana L. (OMEO, SHEO, and SMEO, respectively), were used in fresh turkey sausage processing. The chemical composition and in vitro antimicrobial potential of selected EOs and their mixture were determined. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against foodborne pathogens (Escherichia coli, Salmonella Enteritidis, and Listeria monocytogenes) ranged in the interval of 0.44–7.1 µL/mL. Fresh turkey sausages were produced with EOs addition and marked as follows: TOMEO—0.150 µL/g OMEO; TSHEO—0.150 µL/g SHEO; TSMEO—0.150 µL/g SMEO; TEOM—0.050 µL/g OMEO, 0.050 µL/g SHEO and 0.050 µL/g SMEO, and control (C) (without EOs). Microbiological profile and biogenic amines content in fresh turkey sausages were recorded during storage. The selected EOs and their mixture efficiently reduced bacterial growth and biogenic amines formation and accumulation. The lowest Enterobacteriaceae count and total biogenic amine (BA) concentration were determined through treatment TSHEO. The results of this study show that selected EOs could be useful in fresh turkey sausage processing in order to improve safety and shelf-life. Full article
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16 pages, 1728 KiB  
Article
Screening of Antifungal Activity of Essential Oils in Controlling Biocontamination of Historical Papers in Archives
by Ana Tomić, Olja Šovljanski, Višnja Nikolić, Lato Pezo, Milica Aćimović, Mirjana Cvetković, Jovana Stanojev, Nebojša Kuzmanović and Siniša Markov
Antibiotics 2023, 12(1), 103; https://doi.org/10.3390/antibiotics12010103 - 06 Jan 2023
Cited by 10 | Viewed by 2028
Abstract
The main challenge in controlling the microbiological contamination of historical paper is finding an adequate method that includes the use of cost-effective, harmless, and non-toxic biocides whose effectiveness is maintained over time and without adverse effects on cultural heritage and human health. Therefore, [...] Read more.
The main challenge in controlling the microbiological contamination of historical paper is finding an adequate method that includes the use of cost-effective, harmless, and non-toxic biocides whose effectiveness is maintained over time and without adverse effects on cultural heritage and human health. Therefore, this study demonstrated the possibility of using a non-invasive method of historical paper conservation based on plant essential oils (EOs) application. Evaluation of antimicrobial effects of different EOs (lemongrass, oregano, rosemary, peppermint, and eucalyptus) was conducted against Cladosporium cladosporoides, Aspergillus fumigatus, and Penicillium chrysogenum, which are commonly found on archive papers. Using a mixture of oregano, lemongrass and peppermint in ratio 1:1:1, the lower minimal inhibition concentration (0.78%) and better efficiency during a vapour test at the highest tested distance (5.5 cm) compared with individual EOs was proven. At the final step, this EOs mixture was used in the in situ conservation of historical paper samples obtained from the Archives of Vojvodina. According to the SEM imaging, the applied EOs mixture demonstrates complete efficiency in the inhibition of fungi colonization of archive papers, since fungal growth was not observed on samples, unlike the control samples. Full article
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14 pages, 4922 KiB  
Article
Agar Plate Methods for Assessing the Antibacterial Activity of Thyme and Oregano Essential Oils against S. epidermidis and E. coli
by Chiara Mollea, Francesca Bosco and Davide Fissore
Antibiotics 2022, 11(12), 1809; https://doi.org/10.3390/antibiotics11121809 - 13 Dec 2022
Cited by 3 | Viewed by 5341
Abstract
The resistance to antimicrobials (AMR), especially antibiotics, represents a serious problem and, at the same time, a challenge. In the last decade, a growing interest in the use of essential oils (EOs) as antimicrobial substances was observed. Commercial thyme and oregano EOs are [...] Read more.
The resistance to antimicrobials (AMR), especially antibiotics, represents a serious problem and, at the same time, a challenge. In the last decade, a growing interest in the use of essential oils (EOs) as antimicrobial substances was observed. Commercial thyme and oregano EOs are reported to be the main responsible of the oil antimicrobial efficacy against both Gram-positive and Gram-negative pathogenic bacteria. The aim of the present work was to study the efficacy of EOs against Staphylococcus epidermidis and Escherichia coli in long-time treatments. In a preliminary microdilution test, a MIC value was obtained for thyme EO against S. epidermidis and E. coli. After that, disk diffusion and disk volatilization tests were set up to study the influence of main cultural parameters on EO activity in liquid or vapor phase. Both bacteria were inhibited by thyme and oregano EOs when applied pure (100% v/v) or diluted (75% and 50% v/v): a higher inhibition was observed in a disk diffusion test in which the antimicrobial effect was due to both liquid and vapor phase components. Finally, a comparison with literature data was carried out even if it was not so easy because standard methods are usually modified and adapted to specific case study. For this reason, the results have to be interpreted in relation to the analytical method applied. Full article
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18 pages, 2734 KiB  
Article
The Application of Ultrasonic Waves and Microwaves to Improve Antihyperglycaemic and Antimicrobial Activities of Marrubium vulgare Extracts
by Aleksandra Gavarić, Jelena Vladić, Jelena Vujetić, Dragan Radnović, Ana Volarić, Jelena Živković, Katarina Šavikin and Senka Vidović
Antibiotics 2022, 11(11), 1475; https://doi.org/10.3390/antibiotics11111475 - 25 Oct 2022
Cited by 2 | Viewed by 1272
Abstract
Having scarce information about ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE) of white horehound (Marrubium vulgare L.), the idea has emerged to determine the optimal process parameters for the maximization of polyphenols and to compare the efficiency of these green [...] Read more.
Having scarce information about ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE) of white horehound (Marrubium vulgare L.), the idea has emerged to determine the optimal process parameters for the maximization of polyphenols and to compare the efficiency of these green extraction technologies. The optimal UAE parameters are temperature of 73.6 °C, extraction time of 40 min and ultrasound power of 30.3 W/L, while the optimal MAE parameters are 63.8% ethanol, extraction time of 15 min and microwave power of 422 W. Extract obtained at optimal UAE parameters shows the highest antihyperglycemic activity (α-amylase inhibition: 50.63% and α-glucosidase inhibition: 48.67%), which can potentially be explained by the presence of chlorogenic acid and quercetin, which were not identified in the macerates. The most sensitive bacterial strain to optimal ultrasonic extract is Bacillus cereus, whereas the most sensitive fungal strain is Saccharomyces cerevisiae. Full article
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14 pages, 1728 KiB  
Article
Phytogenic Blend Improves Intestinal Health and Reduces Obesity, Diabetes, Cholesterol and Cancers: A Path toward Customised Supplementation
by Sung J. Yu, Yadav S. Bajagai, Friedrich Petranyi, Sara de las Heras-Saldana, Thi Thu Hao Van and Dragana Stanley
Antibiotics 2022, 11(10), 1428; https://doi.org/10.3390/antibiotics11101428 - 18 Oct 2022
Cited by 1 | Viewed by 1713
Abstract
Poultry production is among the most challenging industries for pathogen control. High animal density and abundance of faecal material demand strict biosecurity measures and continual vigilance in monitoring animal health parameters. Despite this vigilance, dealing with disease outbreaks is a part of farmers’ [...] Read more.
Poultry production is among the most challenging industries for pathogen control. High animal density and abundance of faecal material demand strict biosecurity measures and continual vigilance in monitoring animal health parameters. Despite this vigilance, dealing with disease outbreaks is a part of farmers’ routines. Phytogenic feed additives comprised of herbs, spices, essential oils, and oleoresins have potent antimicrobial and anti-inflammatory actions. Related studies are gaining substantial interest in human and animal health worldwide. In this study, a commercial blend phytogenic feed additive was supplemented to layers in an industrial free-range production system with 20,000 birds in both control and treatment groups. At the end of the trial, the ileum tissue was sampled for RNAseq transcriptomic analysis to study the host reaction to the supplement. Phytogenic supplement significantly inhibited four cholesterol-related pathways and reduced the Arteriosclerosis disease category towards improved cardiovascular health. The supplemented birds exhibited reduced disease susceptibility for 26 cancer categories with p-values in the range from 5.23 × 10−4 to 1.02 × 10−25. Major metabolic shifts in Lipid metabolism in combination with Carbohydrate metabolism have resulted in a decrease in the Obesity category, altering the ratio of fat and carbohydrate metabolism toward lower fat storage. Full article
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Review

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27 pages, 1844 KiB  
Review
Insight on Incorporation of Essential Oils as Antimicrobial Substances in Biopolymer-Based Active Packaging
by Ana Tomić, Olja Šovljanski and Tamara Erceg
Antibiotics 2023, 12(9), 1473; https://doi.org/10.3390/antibiotics12091473 - 21 Sep 2023
Cited by 5 | Viewed by 1276
Abstract
The increasing interest in microbiological food safety requires the development of sensitive and reliable analyses and technologies for preserving food products’ freshness and quality. Different types of packaging systems are one of the solutions for controlling microbiological activity in foods. During the last [...] Read more.
The increasing interest in microbiological food safety requires the development of sensitive and reliable analyses and technologies for preserving food products’ freshness and quality. Different types of packaging systems are one of the solutions for controlling microbiological activity in foods. During the last decades, the development of biopolymer-based active packaging with essential oil incorporation systems has resulted in technologies with exceptional application potential, primarily in the food industry. There is no doubt that this principle can facilitate food status monitoring, reduce food waste, extend the shelf life, improve the overall quality of food, or indicate a larger problem during the storage, production, and distribution of foodstuffs. On the other hand, most antimicrobial packaging systems are in the development phase, while the sensitivity, selectivity, complexity, and, above all, safety of these materials are just some of the essential questions that need to be answered before they can be widely used. The incorporation of essential oils as antimicrobial substances in biopolymer-based active packaging holds significant promise for enhancing food safety, extending shelf life, and offering more sustainable packaging solutions. While challenges exist, ongoing research and innovation in this field are likely to lead to the development of effective and environmentally friendly packaging systems with enhanced antimicrobial properties. Full article
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40 pages, 2952 KiB  
Review
Bacillus VOCs in the Context of Biological Control
by Jovana Grahovac, Ivana Pajčin and Vanja Vlajkov
Antibiotics 2023, 12(3), 581; https://doi.org/10.3390/antibiotics12030581 - 15 Mar 2023
Cited by 11 | Viewed by 2904
Abstract
A contemporary agricultural production system relying on heavy usage of agrochemicals represents a questionable outlook for sustainable food supply in the future. The visible negative environmental impacts and unforeseen consequences to human and animal health have been requiring a shift towards the novel [...] Read more.
A contemporary agricultural production system relying on heavy usage of agrochemicals represents a questionable outlook for sustainable food supply in the future. The visible negative environmental impacts and unforeseen consequences to human and animal health have been requiring a shift towards the novel eco-friendly alternatives for chemical pesticides for a while now. Microbial-based biocontrol agents have shown a promising potential for plant disease management. The bacteria of the genus Bacillus have been among the most exploited microbial active components due to several highly efficient mechanisms of action against plant pathogens, as well as a palette of additional plant-beneficial mechanisms, together with their suitable properties for microbial biopesticide formulations. Among other bioactive metabolites, volatile organic compounds (VOCs) have been investigated for their biocontrol applications, exhibiting the main advantage of long-distance effect without the necessity for direct contact with plants or pathogens. The aim of this study is to give an overview of the state-of-the-art in the field of Bacillus-based VOCs, especially in terms of their antibacterial, antifungal, and nematicidal action as the main segments determining their potential for biocontrol applications in sustainable agriculture. Full article
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