Fermentation

Research

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13 pages, 1595 KiB

Open AccessArticle

Optimization of Fermentation Process of Wheat Germ Protein by Aspergillus niger and Analysis of Antioxidant Activity of Peptide

by Yingying Liu, Yu Zhou, Chaohong Zhu, Yanglin Meng, Jingjing Wang, Xinyang Chen, Yinchen Hou, Aimei Liao, Long Pan and Jihong Huang

Fermentation 2024, 10(3), 121; https://doi.org/10.3390/fermentation10030121 - 22 Feb 2024

Viewed by 1094

Abstract

Utilizing wheat embryos as the raw material and employing Aspergillus niger as the fermentation strain, wheat embryo polypeptides were produced through microbial liquid fermentation. The protein concentration post-fermentation served as the response variable, and the preparation process underwent optimization through single-factor testing and [...] Read more.

Utilizing wheat embryos as the raw material and employing Aspergillus niger as the fermentation strain, wheat embryo polypeptides were produced through microbial liquid fermentation. The protein concentration post-fermentation served as the response variable, and the preparation process underwent optimization through single-factor testing and a response surface methodology, followed by the assessment of antioxidant activity. The findings revealed that the optimal conditions for wheat embryo peptide preparation via Aspergillus niger fermentation included a fermentation duration of 24 h, an inoculum volume of 4%, an initial pH of 7, and a protein concentration of 21.47 mg/mL. Peptides with different molecular weights were then prepared by dead-end filtration. The results showed that F6 (<3 kDa) had strong scavenging ability against DPPH, ABTS, and ·OH radicals, which provided a basis for the preparation of antioxidant peptides in wheat germ and related research. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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16 pages, 2490 KiB

Open AccessArticle

Two-Step Optimization for Improving Prodigiosin Production Using a Fermentation Medium for Serratia marcescens and an Extraction Process

by Xin Wang, Zhihao Cui, Zongyu Zhang, Jiacheng Zhao, Xiaoquan Liu, Guangfan Meng, Jing Zhang and Jie Zhang

Fermentation 2024, 10(2), 85; https://doi.org/10.3390/fermentation10020085 - 30 Jan 2024

Viewed by 1288

Abstract

Prodigiosin (PG) is a secondary metabolite produced by Serratia marcescens which has a promising future in food, textile, and other industries due to its bright color and diverse biological activities. Currently, the production of PG is mainly restricted by the components of the [...] Read more.

Prodigiosin (PG) is a secondary metabolite produced by Serratia marcescens which has a promising future in food, textile, and other industries due to its bright color and diverse biological activities. Currently, the production of PG is mainly restricted by the components of the fermentation medium and large losses during its extraction process, making large-scale industrial production impossible. In this study, a Box–Behnken design (BBD) was used to optimize the response surface of the fermentation medium of S. marcescens. The optimum medium composition was found to be sucrose, 16.29 g/L; peptone, 11.76 g/L; and tween 80, 2.64 g/L. This composition produced a PG amount of 1653.95 ± 32.12 mg/L, which is a 64-fold increase compared to the initial medium. A Box–Behnken design (BBD) was then used to optimize the response surface of the extraction process of PG, aiming to reduce loss during extraction. The optimal extraction conditions were determined to be a solvent fermentation liquid ratio of 9.12:1, an extraction temperature of 25.35 °C, and an extraction time of 30.33 min. These conditions resulted in a final PG production amount of 2142.75 ± 12.55 mg/L, which was nearly 84 times higher than the initial production amount of PG. These results provide essential theoretical and experimental support for the industrial production of PG. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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17 pages, 2975 KiB

Open AccessArticle

Identification and Combinatorial Overexpression of Key Genes for Enhancing ε-Poly-L-lysine Biosynthesis in Streptomyces albulus

by Hongjian Zhang, Hao Yang, Chongyang Zhang, Daojun Zhu, Liang Wang, Jianhua Zhang and Xusheng Chen

Fermentation 2024, 10(1), 65; https://doi.org/10.3390/fermentation10010065 - 17 Jan 2024

Viewed by 1012

Abstract

ε-Poly-L-lysine (ε-PL) is a natural and safe food preservative mainly produced by the aerobic, filamentous bacterium Streptomyces albulus. Therefore, it is crucial to breed superior ε-PL-producing strains to enhance fermentation efficiency to reduce production costs. Metabolic engineering is an effective measure for [...] Read more.

ε-Poly-L-lysine (ε-PL) is a natural and safe food preservative mainly produced by the aerobic, filamentous bacterium Streptomyces albulus. Therefore, it is crucial to breed superior ε-PL-producing strains to enhance fermentation efficiency to reduce production costs. Metabolic engineering is an effective measure for strain modification, but there are few reports on key genes for ε-PL biosynthesis. In this study, metabolic flux analysis was employed to identify potential key genes in ε-PL biosynthesis in S. albulus WG-608. A total of six potential key genes were identified. Three effective key genes (ppc, pyc and pls) were identified for the first time in ε-PL biosynthesis through overexpression experiments. It also presents the first demonstration of the promoting effects of ppc and pyc on ε-PL biosynthesis. Three genes were then co-expressed in S. albulus WG-608 to obtain OE-ppc-pyc-pls, which exhibited an 11.4% increase in ε-PL production compared to S. albulus WG-608, with a 25.5% increase in specific ε-PL production. Finally, the metabolic flux analysis of OE-ppc-pyc-pls compared to S. albulus WG-608 demonstrated that OE-ppc-pyc-pls successfully altered the metabolic flux as expected. This study not only provides a theoretical basis for the metabolic engineering of ε-PL-producing strains but also provides an effective approach for the metabolic engineering of other metabolites. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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14 pages, 2586 KiB

Open AccessArticle

Transcriptional Analysis of Antrodin C Synthesis in Taiwanofungus camphoratus (Syn. Antrodia camphorate, Antrodia cinnamomea) to Understand Its Biosynthetic Mechanism

by Wei Jia, Shu-Ping Gai, Xiao-Hui Li, Jing-Song Zhang and Wen-Han Wang

Fermentation 2024, 10(1), 28; https://doi.org/10.3390/fermentation10010028 - 29 Dec 2023

Viewed by 979

Abstract

Antrodin C, a bioactive component of Taiwanofungus camphoratus, exhibits good immunophysiological and antitumour activities, including a broad spectrum of anticancer effects. Exogenous additives can bind to metabolites during the submerged culture of T. camphoratus and affect secondary metabolite yields. However, the lack [...] Read more.

Antrodin C, a bioactive component of Taiwanofungus camphoratus, exhibits good immunophysiological and antitumour activities, including a broad spectrum of anticancer effects. Exogenous additives can bind to metabolites during the submerged culture of T. camphoratus and affect secondary metabolite yields. However, the lack of molecular genetic studies on T. camphoratus has hindered the study of the antrodin C biosynthetic pathway. In this study, we conducted a ribonucleic acid-sequencing-based transcriptional analysis to identify the differentially expressed genes involved in the synthesis of antrodin C by T. camphoratus, using inositol and maleic acid (MAC) as exogenous additives. The addition of inositol significantly upregulated carbohydrate and sugar metabolism pathway genes (E3.2.1.14, UGDH, and IVD). When MAC was used, amino and nucleotide sugar metabolism and starch and sucrose metabolism pathways were significantly inhibited, and the associated genes (E3.2.1.14 and E3.2.1.58) were also significantly downregulated. The biosynthesis pathway genes for ubiquinone and other terpene quinones (COQ2, ARO8, and wrbA), which may play an important role in antrodin C synthesis, were significantly downregulated. This study advances our understanding of how the additives inositol and MAC affect metabolite biosynthesis in T. camphorates. This could be beneficial in proposing potential strategies for improving antrodin C production using a genetic approach. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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16 pages, 5709 KiB

Open AccessArticle

Comprehensive Analysis of Catalytic Characteristics and Molecular Mechanisms in Mutant Trametes versicolor Strains with Enhanced Laccase Activities

by Chi Zhang, Zhongjie Yan, Xiufang Li, Junming Wang, Xidong Ren and Xinli Liu

Fermentation 2023, 9(12), 995; https://doi.org/10.3390/fermentation9120995 - 22 Nov 2023

Cited by 1 | Viewed by 1162

Abstract

The commercial potential of Trametes versicolor laccases in the degradation of various persistent contaminants is significant. Despite numerous attempts through rational metabolic engineering to enhance the properties of laccases, the outcomes have proven unsatisfactory for practical implementation. The present study successfully generated two [...] Read more.

The commercial potential of Trametes versicolor laccases in the degradation of various persistent contaminants is significant. Despite numerous attempts through rational metabolic engineering to enhance the properties of laccases, the outcomes have proven unsatisfactory for practical implementation. The present study successfully generated two novel mutants, namely, TA-04 and TA-15, derived from Trametes versicolor ATCC20869, utilizing atmospheric and room temperature plasma (ARTP). The laccase activities of TA-04 and TA-15 showed a significant increase to 136.507 ± 4.827 U/mg DCW and 153.804 ± 6.884 U/mg DCW, respectively, which were 1.201 and 1.354 times than that of the original strain. The laccase activities of the mutant strains TA-04 and TA-15 surpassed that of the original strain by 10.372% and 18.914%, respectively, at a higher pH level of five. Sequencing analysis of TA-04 and TA-15 revealed that several alternative amino acids within their active regions may enhance their catalytic characteristics under a higher temperature and pH condition. This study employed ARTP mutagenesis to propose two highly efficient microbial mutants derived from Trametes versicolor ATCC20869, exhibiting enhanced laccase activities. These mutants hold promising potential for the degradation of diverse environmental pollutants. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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20 pages, 3940 KiB

Open AccessArticle

Design-of-Experiment-Guided Establishment of a Fermentative Bioprocess for Biomass-Bound Astaxanthin with Corynebacterium glutamicum

by Florian Meyer, Ina Schmitt, Thomas Schäffer, Volker F. Wendisch and Nadja A. Henke

Fermentation 2023, 9(11), 969; https://doi.org/10.3390/fermentation9110969 - 11 Nov 2023

Cited by 1 | Viewed by 1449

Abstract

Corynebacterium glutamicum is prominent in the industrial production of secreted amino acids. Notably, it naturally accumulates the carotenoid pigment decaprenoxanthin in its membranes. Metabolic engineering enabled the production of astaxanthin. Here, a bioprocess for astaxanthin production in lab-scale stirred bioreactors was established by [...] Read more.

Corynebacterium glutamicum is prominent in the industrial production of secreted amino acids. Notably, it naturally accumulates the carotenoid pigment decaprenoxanthin in its membranes. Metabolic engineering enabled the production of astaxanthin. Here, a bioprocess for astaxanthin production in lab-scale stirred bioreactors was established by a DoE-guided approach to optimize the basic process parameters pH, rDOS, aeration rate as well as inoculation cell density. The DoE-guided approach to characterize 2 L scale cultivation revealed that the pH showed the strongest effect on the product formation. Subsequently, an optimum at pH 8, an aeration rate of 0.25 vvm, 30% rDOS and an initial optical density of 1 was established that allowed production of 7.6 ± 0.6 mg L⁻¹ astaxanthin in batch mode. These process conditions were successfully transferred to a fed-batch process resulting in a high cell density cultivation with up to 60 g CDW L⁻¹ biomass and 64 mg L⁻¹ astaxanthin and thus demonstrating an about 9-fold improvement compared to optimal batch conditions. Moreover, pH-shift experiments indicate that the cells can quickly adapt to a change from pH 6 to 8 and start producing astaxanthin, showing the possibility of biphasic bioprocesses for astaxanthin production. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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21 pages, 2517 KiB

Open AccessArticle

Co-Fermentation of Glucose–Xylose–Cellobiose–XOS Mixtures Using a Synthetic Consortium of Recombinant Saccharomyces cerevisiae Strains

by Ning Yan, Tao Luan, Mengqi Yin, Yaping Niu, Longhao Wu, Shuo Yang, Zailu Li, Hongxing Li, Jianzhi Zhao and Xiaoming Bao

Fermentation 2023, 9(8), 775; https://doi.org/10.3390/fermentation9080775 - 19 Aug 2023

Viewed by 1126

Abstract

The efficient conversion of cellulosic sugars is vital for the economically viable production of biofuels/biochemicals from lignocellulosic biomass hydrolysates. Based on comprehensive screening, Saccharomyces cerevisiae RC212 was chosen as the chassis strain for multiple integrations of heterologous β-glucosidase and β-xylosidase genes in the [...] Read more.

The efficient conversion of cellulosic sugars is vital for the economically viable production of biofuels/biochemicals from lignocellulosic biomass hydrolysates. Based on comprehensive screening, Saccharomyces cerevisiae RC212 was chosen as the chassis strain for multiple integrations of heterologous β-glucosidase and β-xylosidase genes in the present study. The resulting recombinant BLN26 and LF1 form a binary synthetic consortium, and this co-culture system achieved partial fermentation of four sugars (glucose, xylose, cellobiose, and xylo-oligosaccharides). Then, we developed a ternary S. cerevisiae consortium consisting of LF1, BSGIBX, and 102SB. Almost all four sugars were efficiently fermented to ethanol within 24 h, and the ethanol yield is 0.482 g g⁻¹ based on the consumed sugar. To our knowledge, this study represents the first exploration of the conversion of mixtures of glucose, xylose, cellobiose, and xylo-oligosaccharides by a synthetic consortium of recombinant S. cerevisiae strains. This synthetic consortium and subsequent improved ones have the potential to be used as microbial platforms to produce a wide array of biochemicals from lignocellulosic hydrolysates. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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11 pages, 3070 KiB

Open AccessCommunication

Biosynthesis of Glucaric Acid by Recombinant Strain of Escherichia coli Expressing Two Different Urinate Dehydrogenases

by Xinchao Yang, Linlin Niu, Chunjiang Ye, Yuanxiu Wang, Yuehui Liu, Fang Wang and Naxin Sun

Fermentation 2023, 9(8), 764; https://doi.org/10.3390/fermentation9080764 - 17 Aug 2023

Viewed by 1169

Abstract

D-glucaric acid is an important bio-based building block of polymers and is a high value-added chemical that can be used in a variety of applications. In the present study, the Udh target genes from Pseudomonas putida and Pseudomonas syringae were used together to [...] Read more.

D-glucaric acid is an important bio-based building block of polymers and is a high value-added chemical that can be used in a variety of applications. In the present study, the Udh target genes from Pseudomonas putida and Pseudomonas syringae were used together to construct the expression vector pETDuet-2 × Udh. The transformants of BL21 (DE3) with vector pETDuet-2 × Udh were applied to produce glucaric acid from glucuronic acid. After optimizing the induction conditions, the highest Udh expression was achieved when 0.4 mmol·L⁻¹ isopropyl-β-d–thiogalactoside (IPTG) was added to the cell cultures at an OD₆₀₀ value of 0.6 followed by culturing at 26 °C for 6 h. The production of glucaric acid substantially reached 5.24 ± 0.015 g·L⁻¹ in fed-batch cultures in a 30 L tank. In the present study, a new system for glucaric acid production was established, which was more economic and friendly to the environment. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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18 pages, 3100 KiB

Open AccessArticle

High-Efficient Production of Cellulosic Ethanol from Corn Fiber Based on the Suitable C5/C6 Co-Fermentation Saccharomyces cerevisiae Strain

by Menglei Li, Fadi Xu, Yuping Zhao, Dongming Sun, Jiao Liu, Xiaolong Yin, Zailu Li, Jianzhi Zhao, Hongxing Li and Xiaoming Bao

Fermentation 2023, 9(8), 743; https://doi.org/10.3390/fermentation9080743 - 09 Aug 2023

Cited by 1 | Viewed by 1359

Abstract

As a potential alternative to fossil-based fuels, cellulosic ethanol has attracted much attention due to its great benefit to energy sustainability and environmental friendliness. However, at present, the industrial competitiveness of cellulosic ethanol production is still insufficient compared with fossil-based fuels because of [...] Read more.

As a potential alternative to fossil-based fuels, cellulosic ethanol has attracted much attention due to its great benefit to energy sustainability and environmental friendliness. However, at present, the industrial competitiveness of cellulosic ethanol production is still insufficient compared with fossil-based fuels because of the higher costs. Expanding the range of lignocellulosic biomass may be a promising measure to promote the economical production of cellulosic ethanol. Corn fiber, a byproduct from the corn deep-processing, is an attractive feedstock for cellulosic ethanol production because of its rich carbohydrate content (generally exceeding 65% of dry weight), almost no transportation cost, and low lignin content allow it to be easily handled. This study first optimized the hydrolysis conditions, including the pretreatment and enzymolysis process based on dilute sulfuric acid, to achieve a high sugar yield. Then, the corn fiber hydrolysates obtained under different hydrolysis conditions were suitably fermented by different C5/C6 co-fermentation Saccharomyces cerevisiae, indicating that the hydrolysate at high solid loading (20%) needs to detoxification to a certain extent but not low solid loading (10%) to achieve high ethanol yield. Finally, the fermentation of the 20% solid loading hydrolysates with resin detoxification was performed in a 50 L bioreactor, achieving the sugar (glucose and xylose) metabolic rate of 2.24 g L ⁻¹ h ⁻¹ and ethanol yield of 92% of the theoretical value, which are the highest reported levels to date. This study provided a potential process route for cellulosic ethanol production from corn fiber from the perspective of the suitability between the upstream hydrolysis process and the downstream fermentation strain. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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12 pages, 2415 KiB

Open AccessArticle

Improvement of ε-Poly-l-lysine Production by Co-Culture Fermentation Strategy

by Long Pan, Cunjin Zhang, Xinyu Yuan, Yu Zhang, Xusheng Chen, Cuizhu Tian, Zishan Zhang, Mengqing Tian, Aimei Liao, Guanghai Yu, Ming Hui, Xin Zeng and Jihong Huang

Fermentation 2023, 9(7), 626; https://doi.org/10.3390/fermentation9070626 - 30 Jun 2023

Cited by 1 | Viewed by 1044

Abstract

ε-poly-l-lysine (ε-PL) has been routinely used as a natural and safe preservative for many years in the food industry. However, most existing production methods struggle to achieve low cost and high production simultaneously. In this work, we present a co-culture fermentation [...] Read more.

ε-poly-l-lysine (ε-PL) has been routinely used as a natural and safe preservative for many years in the food industry. However, most existing production methods struggle to achieve low cost and high production simultaneously. In this work, we present a co-culture fermentation strategy to enhance ε-PL production. Specifically, we screened a strain from five different strains that could be co-cultured with Streptomyces albulus to raise the production of ε-PL. Subsequently, a single factor experiment and response surface design were used to optimize the conditions of co-culture fermentation to further improve the production of ε-PL. Moreover, the optimal fermentation process was successfully verified in a 2-L fermentor with fed batch fermentation. The production of ε-PL reached 27.07 ± 0.47 g/L by 144 h. Compared with single strain (S. albulus) fermentation, the production of ε-PL was increased by 31.47%. At the same time, the amount of bacteria increased by 19.62%, which means that the ε-PL synthesis ability of bacteria had been improved. All the obtained results showed great potential for co-culture fermentation in large-scale ε-PL production and provide a new fermentation strategy for ε-PL biosynthesis. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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14 pages, 2242 KiB

Open AccessArticle

Comparison of Raspberry Ketone Production via Submerged Fermentation in Different Bioreactors

by Yi Zhang, Eric Charles Peterson, Yuen Ling Ng, Kheng-Lim Goh, Vladimir Zivkovic and Yvonne Chow

Fermentation 2023, 9(6), 546; https://doi.org/10.3390/fermentation9060546 - 06 Jun 2023

Viewed by 1517

Abstract

Raspberry ketone (RK) has high commercial value in the food and healthcare industries. A biological route to this flavour compound is an attractive prospect, considering the need to meet consumer demands and sustainable goals; however, it is yet to become an industrial reality. [...] Read more.

Raspberry ketone (RK) has high commercial value in the food and healthcare industries. A biological route to this flavour compound is an attractive prospect, considering the need to meet consumer demands and sustainable goals; however, it is yet to become an industrial reality. In this work, fungal production of raspberry ketone (RK) and raspberry compounds (RC) via submerged fermentation of Nidula niveo-tomentosa was characterized in flask, stirred-tank reactor (STR), panel bioreactor (PBR), and fluidized bed reactor (FBR) configurations. The results indicate that the panel bioreactor resulted in larger, floccose pellets accompanied by maximum titres of 20.6 mg/L RK and 50.9 mg/L RC. The stirred-tank bioreactor with impeller mixing yielded compact elliptical pellets, induced the highest volumetric productivity of 2.0 mg L⁻¹ day⁻¹, and showed RK selectivity of 0.45. While differing mixing strategies had clear effects on pellet morphology, RK production presented a more direct positive relationship with cultivation conditions, and showed appropriate mixing and aeration favour RK to raspberry alcohol (RA). Overall, this paper highlights the importance of bioreactor design to fungal fermentation, and gives insight into green and industrial bioproduction of value-added natural compounds. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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Review

Jump to: Research

9 pages, 526 KiB

Open AccessReview

The Application of Corynebacterium glutamicum in l-Threonine Biosynthesis

by Min Duan, Shuo Chen, Xinli Liu, Jianhang Liu and Deqiang Zhu

Fermentation 2023, 9(9), 822; https://doi.org/10.3390/fermentation9090822 - 08 Sep 2023

Viewed by 1490

Abstract

l-threonine is an essential amino acid in human and animal nutrition. It is widely used in food, medicine, feed, and other fields. The global market scale exceeds 700,000 tons per year. Corynebacterium glutamicum, as a chassis cell for industrial amino acid [...] Read more.

l-threonine is an essential amino acid in human and animal nutrition. It is widely used in food, medicine, feed, and other fields. The global market scale exceeds 700,000 tons per year. Corynebacterium glutamicum, as a chassis cell for industrial amino acid production, has the advantages of biological safety and strong environmental adaptability, and is a potential strain for the efficient production of l-threonine. This article systematically reviewed the function and application of l-threonine, the pathway of C. glutamicum to synthesize l-threonine, and the use of metabolic engineering technology to improve the production of l-threonine. Full article

(This article belongs to the Special Issue Optimization and Analysis of Fermentation Process for Microbial Products)

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