Fermentation

26 pages, 649 KiB

Open AccessReview

Efficacy of Probiotics in Reducing Pathogenic Potential of Infectious Agents

by Poonam Vinayamohan, Divya Joseph, Leya Susan Viju, Sangeetha Ananda Baskaran and Kumar Venkitanarayanan

Fermentation 2024, 10(12), 599; https://doi.org/10.3390/fermentation10120599 (registering DOI) - 24 Nov 2024

Abstract

Probiotics exhibit significant antivirulence properties that are instrumental in mitigating infectious agents not only within the gastrointestinal tract but also in other parts of the body, including respiratory and urogenital systems. These live microorganisms, beneficial to health when administered in appropriate quantities, operate [...] Read more.

Probiotics exhibit significant antivirulence properties that are instrumental in mitigating infectious agents not only within the gastrointestinal tract but also in other parts of the body, including respiratory and urogenital systems. These live microorganisms, beneficial to health when administered in appropriate quantities, operate through several key mechanisms to reduce the pathogenic potential of bacteria, viruses, and fungi. Probiotics effectively reduce colonization and infection severity by enhancing the host’s immune response and directly antagonizing pathogens. One of the major modes of action includes the disruption of quorum sensing pathways, which are essential for bacterial communication and the regulation of virulence factors. Additionally, probiotics compete with pathogens for adhesion sites on host tissues, effectively blocking the establishment and proliferation of infections within a host. This multifaceted interference with pathogen mechanisms highlights the therapeutic potential of probiotics in controlling infectious diseases and enhancing host resilience. This review provides a detailed analysis of these mechanisms, underscoring the potential of probiotics for therapeutic applications to enhance public health. Full article

(This article belongs to the Special Issue Probiotics, Prebiotics and Their Use as Innovative Ingredients in Food Technology)

15 pages, 2618 KiB

Open AccessArticle

Wineinformatics: Wine Score Prediction with Wine Price and Reviews

by Yuka Nagayoshi and Bernard Chen

Fermentation 2024, 10(12), 598; https://doi.org/10.3390/fermentation10120598 (registering DOI) - 23 Nov 2024

Abstract

Wineinformatics is a new field that applies data science to wine-related data. The goal of this paper is to determine whether incorporating wine price can improve the accuracy of score prediction. To explore the relationship between wine price and wine score, naive Bayes [...] Read more.

Wineinformatics is a new field that applies data science to wine-related data. The goal of this paper is to determine whether incorporating wine price can improve the accuracy of score prediction. To explore the relationship between wine price and wine score, naive Bayes classifier and support vector machine (SVM) classifier are employed to predict the scores as either equal to or above 90 or below 90. The price values are normalized using four different methods: mean, median, boxplot mean, and boxplot median. To conduct a proper comparison, the original dataset from previous research, which includes a total of 14,349 wine reviews, was preprocessed by filtering all null price values, resulting in 9721 wine reviews. Using this dataset, classifiers, and normalization methods, the models with and without the price feature were compared. SVM classifier with mean normalization method (USD 50.04) achieved the best accuracy of 87.98%, while naive Bayes classifier with boxplot median normalization method (USD 28.00) showed the greatest improvement of 0.99%. From all the results, we concluded that boxplot median normalization (USD 28.00) is the most effective method in this study. These results indicate that incorporating price as an attribute enhances machine learning algorithms’ ability to recognize the correlation between wine reviews and scores. Full article

(This article belongs to the Special Issue Applications of Computer Science and AI to Fermented Foods and Beverages)

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15 pages, 1190 KiB

Open AccessArticle

Improving the Synthesis of Odd-Chain Fatty Acids in the Oleaginous Yeast Yarrowia lipolytica

by Nour Tabaa Chalabi, Sally El Kantar, Camilla Pires De Souza, Anissa Khelfa, Jean-Marc Nicaud, Espérance Debs, Nicolas Louka and Mohamed Koubaa

Fermentation 2024, 10(12), 597; https://doi.org/10.3390/fermentation10120597 - 22 Nov 2024

Abstract

(1) Background: Odd-chain fatty acids (OCFAs) have garnered attention for their potential health benefits and unique roles in various biochemical pathways. Yarrowia lipolytica, a versatile yeast species, is increasingly studied for its capability to produce OCFAs under controlled genetic and environmental conditions. [...] Read more.

(1) Background: Odd-chain fatty acids (OCFAs) have garnered attention for their potential health benefits and unique roles in various biochemical pathways. Yarrowia lipolytica, a versatile yeast species, is increasingly studied for its capability to produce OCFAs under controlled genetic and environmental conditions. However, optimizing the synthesis of specific OCFAs, such as cis-9-heptadecenoic acid (C17:1), remains a challenge. (2) Methods: The gene coding for the Δ9 fatty acid desaturase, YlOLE1, and the gene coding the diacylglycerol O-acyltransferase 2, YlDGA2, were overexpressed in Y. lipolytica. With the engineered strain, the main goal was to fine-tune the production of OCFA-enriched lipids by optimizing the concentrations of sodium propionate and sodium acetate used as precursors for synthesizing odd- and even-chain fatty acids, respectively. (3) Results: In the strain overexpressing only YlDGA2, no significant changes in fatty acid composition or lipid content were observed compared to the control strain. However, in the strain overexpressing both genes, while no significant changes in lipid content were noted, a significant increase was observed in OCFA content. The optimal conditions for maximizing the cell density and the C17:1 content in lipids were found to be 2.23 g/L of sodium propionate and 17.48 g/L of sodium acetate. These conditions resulted in a cell density (optical density at 600 nm) of 19.5 ± 0.46 and a C17:1 content of 45.56% ± 1.29 in the culture medium after 168 h of fermentation. (4) Conclusions: By overexpressing the YlOLE1 gene and optimizing the concentrations of fatty acid precursors, it was possible to increase the content of OCFAs, mainly C17:1, in lipids synthesized by Y. lipolytica. Full article

(This article belongs to the Special Issue Yarrowia lipolytica: A Beneficial Yeast as a Biofactory for Biotechnological Applications: 3rd Edition)

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4 pages, 166 KiB

Open AccessEditorial

Application of Fermentation Technology in Animal Nutrition

by Siran Wang

Fermentation 2024, 10(12), 596; https://doi.org/10.3390/fermentation10120596 - 22 Nov 2024

Abstract

Fermentation technology has been utilized in animal nutrition worldwide for an extended period, with particular focus on animal feed [...] Full article

(This article belongs to the Special Issue Application of Fermentation Technology in Animal Nutrition)

21 pages, 2723 KiB

Open AccessArticle

Production, Purification, and Characterization of Extracellular Lipases from Hyphopichia wangnamkhiaoensis and Yarrowia deformans

by Misael Romo-Silva, Emanuel Osmar Flores-Camargo, Griselda Ma. Chávez-Camarillo and Eliseo Cristiani-Urbina

Fermentation 2024, 10(12), 595; https://doi.org/10.3390/fermentation10120595 - 21 Nov 2024

Abstract

The efficient production of microbial lipases from organic wastes has garnered great interest because of the diverse and potential biotechnological applications of these enzymes. However, the extracellular lipases from the novel yeast strains Hyphopichia wangnamkhiaoensis and Yarrowia deformans remain uncharacterized. Thus, this study [...] Read more.

The efficient production of microbial lipases from organic wastes has garnered great interest because of the diverse and potential biotechnological applications of these enzymes. However, the extracellular lipases from the novel yeast strains Hyphopichia wangnamkhiaoensis and Yarrowia deformans remain uncharacterized. Thus, this study aimed to investigate the characteristics and production of lipases from both yeasts. Lipases from H. wangnamkhiaoensis and Y. deformans were purified and biochemically characterized, and their production was measured in batch cultures with olive oil (reference), waste cooking oil, and glycerol as substrates. The purified lipases from H. wangnamkhiaoensis and Y. deformans had molecular weights of approximately 33 and 45 kDa, respectively. Their activities on p-nitrophenyl palmitate were optimal at pH 8.0 and 40 °C. Moreover, the activities of the lipases were inhibited by ethylenediaminetetraacetic acid, phenylmethylsulfonyl fluoride, and 4-(2-aminoethyl)benzenesulfonyl fluoride, and were reactivated by Ca²⁺ and Mg²⁺, indicating that both lipases are metalloenzymes and serine-type enzymes. The lipases were more tolerant to hydrophilic solvents than to hydrophobic solvents, and they followed Michaelis–Menten kinetics. Among the various substrates used, waste cooking oil yielded the highest lipase production and productivity. These results indicate that H. wangnamkhiaoensis and Y. deformans are suitable and potential candidates for lipase production. Full article

(This article belongs to the Special Issue Metabolic Engineering of Yeast for the Production of Fuels and Chemicals)

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17 pages, 8122 KiB

Open AccessArticle

Enhanced Production of Acid Phosphatase in Bacillus subtilis: From Heterologous Expression to Optimized Fermentation Strategy

by Yang Liu, Wenjing Shuai, Zheng Xu, Xiao Yu, Zhong Yao, Ping Wei, Fang Ni and Yang Sun

Fermentation 2024, 10(12), 594; https://doi.org/10.3390/fermentation10120594 - 21 Nov 2024

Abstract

Acid phosphatases (ACPase, EC 3.1.3.2) are hydrolytic enzymes widely distributed in both plant and animal tissues. Despite their ubiquitous presence, the production and specific activity of ACPase in these sources remain suboptimal. Consequently, the development of microbial cell factories for large-scale ACPase production [...] Read more.

Acid phosphatases (ACPase, EC 3.1.3.2) are hydrolytic enzymes widely distributed in both plant and animal tissues. Despite their ubiquitous presence, the production and specific activity of ACPase in these sources remain suboptimal. Consequently, the development of microbial cell factories for large-scale ACPase production has emerged as a significant research focus. In this study, we successfully expressed the phosphatase PAP2 family protein (acid phosphatase) from Acinetobacter nosocomialis 1905 in Bacillus subtilis 168. The specific activity of the crude enzyme solution was 59.60 U/mg. After purification, the enzyme activity increased to 86.62 U/mL, with a specific activity of 129.60 U/mg. Characterization of the enzyme revealed optimal activity at 45 °C and a pH of 6.0. The Km value was determined to be 0.25 mmol/L using p-nitrophenylphosphoric acid disodium salt as the substrate. Additionally, the enzyme activity was found to be enhanced by the presence of Ni²⁺. Dissolved oxygen and medium were subsequently optimized during fermentation on the basis of a commercially available 5 L bioreactor. The recombinant strain B. subtilis 168/pMA5-Acp achieved maximal volumetric enzyme activity of 136.9 U/mL after 12 h of fermentation under optimized conditions: an aeration rate of 1.142 VVM (4 lpm), an agitation speed of 350 rpm, and an optimal ratio of lactose to fish powder (7.5 g/L:12.5 g/L). These optimizations resulted in a 5.9-fold increase in volumetric enzyme activity, a 4.9-fold increase in enzyme synthesis per unit cell volume, and a 48.6% increase in biomass concentration. This study establishes a comprehensive technological framework for prokaryotic fermentation-based ACPase production, potentially addressing the bottleneck in industrial-scale applications. Full article

(This article belongs to the Special Issue Applied Microorganisms and Industrial/Food Enzymes, 2nd Edition)

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17 pages, 3297 KiB

Open AccessArticle

Serial Re-Pitching of Yeast Impacts Final Flavor Profiles of Commercial Beer

by Fina Beth Nelson, Joshua Pickering, Casey Murray and Christopher Eskiw

Fermentation 2024, 10(11), 593; https://doi.org/10.3390/fermentation10110593 - 20 Nov 2024

Abstract

The aroma-active compounds produced by Saccharomyces cerevisiae during the fermentation of wort are key to the unique aroma and flavour profiles of beer. In commercial fermentations, there is batch-to-batch variation depending on yeast “brewing fitness” or the health of the yeast, but how [...] Read more.

The aroma-active compounds produced by Saccharomyces cerevisiae during the fermentation of wort are key to the unique aroma and flavour profiles of beer. In commercial fermentations, there is batch-to-batch variation depending on yeast “brewing fitness” or the health of the yeast, but how does yeast health impact fermentation performance and metabolite production during fermentation? To address this, daily samples were collected from three full-scale commercial fermentations. The specific gravity was measured immediately, and samples were collected for carbohydrate analysis by High-Performance Liquid Chromatography and volatile compound analysis by Head-Space Gas Chromatography Mass Spectrometry (HS-GC-MS). Acetate esters (3), medium-chain fatty acid ethyl esters (7), hop-derived compounds (3), and an off-flavour (1) were detected and identified, and their relative signal was recorded for each sample. While there did not appear to be an effect of generational age on the duration of fermentation, age, in terms of the number of generations from serial re-pitching, impacted the ratios of volatile compounds. This difference in ratios was observed as early as Day 2, resulting in a difference in the volatile compound profiles of finished beers, therefore resulting in inconsistency in the product. This is important knowledge for brewers as generational age must be considered when fermenting high-quality, consistent products and monitoring fermentation progress/duration may not be enough to determine the ability of yeast to produce balanced flavour profiles. Full article

(This article belongs to the Section Fermentation for Food and Beverages)

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11 pages, 1546 KiB

Open AccessArticle

Effect of Different Partial Pressures on H₂ Production with Parageobacillus thermoglucosidasius DSM 6285

by Magda Stephania Ardila, Habibu Aliyu, Pieter de Maayer and Anke Neumann

Fermentation 2024, 10(11), 592; https://doi.org/10.3390/fermentation10110592 - 19 Nov 2024

Abstract

The ability of Parageobacillus thermoglucosidasius to produce H₂ from CO via the water–gas shift (WGS) reaction makes it a compelling microorganism for biofuels research. Optimizing this process requires evaluating parameters such as pressure. This study aimed to understand how H₂ production [...] Read more.

The ability of Parageobacillus thermoglucosidasius to produce H₂ from CO via the water–gas shift (WGS) reaction makes it a compelling microorganism for biofuels research. Optimizing this process requires evaluating parameters such as pressure. This study aimed to understand how H₂ production is affected by increasing CO, N₂, and H₂ partial pressures to 1.0, 2.0, and 3.0 bar. Increasing CO partial pressure can improve the solubility of the gas in the liquid phase. However, raising CO partial pressure to 3.0 bar had an inhibitory effect, delaying and reducing H₂ production. By contrast, increasing N₂ and H₂ partial pressures to 3.0 bar had positive effects, reaching a H₂ production of 9.2 mmol and 130 mmol, respectively. Analysis of the electron balance at the end of the fermentation process showed that the selectivity toward H₂ production reached 95%, with the remainder of electrons deriving from CO and glucose directed at organic acid production, mainly acetate, followed by formate. Full article

(This article belongs to the Special Issue Fermentative Biohydrogen Production, 2nd Edition)

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24 pages, 6222 KiB

Open AccessArticle

Evaluating the Performance of Anaerobic Digestion with Upstream Thermal Hydrolysis—What Role Does the Activated Sludge Process Play?

by Johannes Rühl and Markus Engelhart

Fermentation 2024, 10(11), 591; https://doi.org/10.3390/fermentation10110591 - 17 Nov 2024

Abstract

The performance of anaerobic digestion of mixed sludge (MS) with upstream thermal hydrolysis of waste activated sludge (WAS) was evaluated and compared to conventional anaerobic digestion. In contrast to previous studies, this work focuses on the evaluation of the impact of the activated [...] Read more.

The performance of anaerobic digestion of mixed sludge (MS) with upstream thermal hydrolysis of waste activated sludge (WAS) was evaluated and compared to conventional anaerobic digestion. In contrast to previous studies, this work focuses on the evaluation of the impact of the activated sludge process, which was assessed using a temperature-normalized solids retention time (SRT_ASP,T). For this purpose, data from a full-scale wastewater treatment plant related to SRT_ASP,T, primary sludge (PS) and WAS production were combined with experimental data from laboratory-scale anaerobic digestion of PS, WAS, thermally hydrolyzed WAS, and MS. The parameter SRT_ASP,T was used as a key link between the full-scale and experimental data. For WAS, SRT_ASP,T essentially influenced the efficacy of thermal hydrolysis on the performance of anaerobic digestion. The increase in methane yield was higher with increasing SRT_ASP,T. When considering MS, however, the increase was significantly lower and leveled out over the investigated range of SRT_ASP,T, mainly due to corresponding WAS/MS ratios. This study demonstrates that the knowledge of SRT_ASP,T, sludge production, and anaerobic degradability enables the assessment of the potential of thermal hydrolysis and its effect on anaerobic digestion. Full article

(This article belongs to the Special Issue Anaerobic Digestion of Sewage Sludge: New Insights and Future Challenges)

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14 pages, 1634 KiB

Open AccessArticle

Exploring Ultrasonic Energy Followed by Natural Fermentation Processing to Enhance Functional Properties and Bioactive Compounds in Millet (Pennisetum glaucum L.) Grains

by Mohammed Saeed Alkaltham, Akram A. Qasem, Mohamed A. Ibraheem and Amro B. Hassan

Fermentation 2024, 10(11), 590; https://doi.org/10.3390/fermentation10110590 - 17 Nov 2024

Abstract

This study explores the effect of ultrasonic treatment followed by fermentation on the in vitro protein digestibility, protein solubility, functional properties, antioxidant activity, total carotenoid content, and gamma-aminobutyric acid (GABA) levels in millet grains. Ultrasonic treatment was applied at different temperatures (20, 40, [...] Read more.

This study explores the effect of ultrasonic treatment followed by fermentation on the in vitro protein digestibility, protein solubility, functional properties, antioxidant activity, total carotenoid content, and gamma-aminobutyric acid (GABA) levels in millet grains. Ultrasonic treatment was applied at different temperatures (20, 40, and 60 °C). The findings indicated significant improvements in phenolic and flavonoid contents and antioxidant activity in terms of the results of the DPPH, FRAP, and ABTS assays of millet grains after ultrasonic treatment alone or combined with fermentation. Moreover, the carotenoid and GABA contents were found to be significantly higher in the ultrasonic-treated grains. The protein solubility functional properties of the millet grains were also improved after the ultrasonic treatment alone or coupled with the fermentation process. Principal component analysis (PCA) revealed that the combined ultrasonic treatment and fermentation of the millet grains could enhance their antioxidant activity, functional characteristics, and vital compounds. Furthermore, the partial least squares (PLS) validation model emphasised that the ultrasonic treatment of millet at 40 °C, followed by fermentation, is the most optimal treatment among the other treatments. Hence, the conclusions highlight the potential of combined ultrasonic (40 °C) and fermentation treatments to improve grains’ nutritional value and functional properties, making millet more suitable for use in health-promoting food products. Full article

(This article belongs to the Section Fermentation Process Design)

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16 pages, 4028 KiB

Open AccessArticle

HOM2 Deletion by CRISPR-Cas9 in Saccharomyces cerevisiae for Decreasing Higher Alcohols in Whiskey

by Jiaojiao He, Haoyang Zhou, Jine Liang, Kadireya Tuerxun, Zhuoling Ding and Shishui Zhou

Fermentation 2024, 10(11), 589; https://doi.org/10.3390/fermentation10110589 - 17 Nov 2024

Abstract

In typical whiskey, the content of higher alcohols is about 1500–2000 mg/L, leading to a high intoxicating degree (ID). To produce low-ID whiskey, Saccharomyces cerevisiae XF0-h, XF0-H and XF0-LH were successfully constructed by CRISPR-Cas9 gene editing technology to knockout HOM2 (encoding aspartate β-semialdehyde [...] Read more.

In typical whiskey, the content of higher alcohols is about 1500–2000 mg/L, leading to a high intoxicating degree (ID). To produce low-ID whiskey, Saccharomyces cerevisiae XF0-h, XF0-H and XF0-LH were successfully constructed by CRISPR-Cas9 gene editing technology to knockout HOM2 (encoding aspartate β-semialdehyde dehydrogenase) in the original strain XF0 and the LEU1 knockout strain XF0-L. The contents of higher alcohols in whiskey fermented by XF0-h, XF0-H, and XF0-LH were 704 ± 8 mg/L, 685 ± 6 mg/L, and 685 ± 19 mg/L, respectively, showing reductions of 23.93%, 25.98%, and 15.81% compared to XF0, XF0, and XF0-L. The fermentation conditions of XF0-LH were optimized through single-factor experiments and the Box–Behnken design. The optimal conditions were a wort concentration of 9.8 °P, hydrolyzed broken rice syrup addition of 78 g/L, and an inoculum size of 2.7 × 10⁶ cells/mL. The low-ID whiskey was brewed with a higher alcohol content of 556 mg/L by 50 L fermenter at the optimal conditions. Full article

(This article belongs to the Special Issue New Research on Fungal Secondary Metabolites, 2nd Edition)

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16 pages, 3241 KiB

Open AccessArticle

Enhanced Fumagillin Production by Optimizing Fermentation and Purification Techniques

by Zili Feng, Pengfei Du, Yunzhi Sheng, Bin Wang, Wang Chen and Hao Peng

Fermentation 2024, 10(11), 588; https://doi.org/10.3390/fermentation10110588 - 14 Nov 2024

Abstract

Fumagillin is a complex biomolecule. Nowadays, the separation and purification techniques of fumagillin still need to be optimized. In this study, the yield of fumagillin was examined in relation to temperature, pH, inoculation volume, rotation speed, and liquid volume. By using single-factor optimization, [...] Read more.

Fumagillin is a complex biomolecule. Nowadays, the separation and purification techniques of fumagillin still need to be optimized. In this study, the yield of fumagillin was examined in relation to temperature, pH, inoculation volume, rotation speed, and liquid volume. By using single-factor optimization, a factorial design, and response surface methodology, the fumagillin yield increased from 10~15% to 30~35%. After scaling up the fermentation process, the fumagillin yield remained stable at 30–35%. In addition, fumagillin was prepared via high-performance preparative liquid chromatography; the yield of the preparation was 77.29%, and the purity was greater than 99%. To sum up, these findings demonstrated that the issue of low fumagillin yield can be resolved by optimizing the fermentation process and introducing the high-performance liquid chromatographic method for the rapid preparation of fumagillin with high recoveries. The findings of this study may serve as a foundation for the large-scale production of fumagillin. Full article

(This article belongs to the Section Industrial Fermentation)

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14 pages, 5002 KiB

Open AccessArticle

Optimization of the Culture Medium of Beauveria bassiana and Spore Yield Using Response Surface Methodology

by Hanxiao Lou, Qizheng Luo, Qingqing Guo, Runshen Su, Jianfeng Liu, Hongli He and Yunqing Cheng

Fermentation 2024, 10(11), 587; https://doi.org/10.3390/fermentation10110587 - 14 Nov 2024

Abstract

Beauveria bassiana has distinct nutrient requirements depending on the growth stage, with the mycelial growth stage being particularly nutrient-intense. When nutrients are exhausted, B. bassiana produces numerous spores that re-germinate and release visible hyphae under suitable environmental conditions. This study aimed to use [...] Read more.

Beauveria bassiana has distinct nutrient requirements depending on the growth stage, with the mycelial growth stage being particularly nutrient-intense. When nutrients are exhausted, B. bassiana produces numerous spores that re-germinate and release visible hyphae under suitable environmental conditions. This study aimed to use low-cost agricultural by-products for developing an optimized sporulation medium. Single-factor experiments revealed that potato, wheat bran, and wheat had the greatest influence on sporulation after 14 d of culture. Wheat, wheat bran, and corncob had the strongest effect on spore production. Using a mathematical model and Box–Behnken design, the maximum predicted sporulation using the stock medium was 5.55 × 10⁶/mL. The optimized formula comprised 54.82 g potato, 77.74 g wheat bran, and 101.48 g wheat. The actual stock medium produced a spore yield of 5.52 × 10⁶/mL. Similarly, the maximum predicted sporulation was 15.66 × 10⁶/mL for the culture medium. The optimized formula comprised 50.81 g wheat, 99.6 g wheat bran, and 112.59 g corncob, with a spore yield of 15.69 × 10⁶/mL. The high consistency between predicted and experimental values indicated that our model can accurately determine the effect of medium on sporulation. Full article

(This article belongs to the Section Fermentation Process Design)

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15 pages, 3908 KiB

Open AccessArticle

Effect of Mixed Culture and Organic Loading Rate over Butanol Production from Biodiesel Waste in an Upflow Packed-Bed Reactor

by Cristina Aglaia Alves Tottoli e Silva, Maria Ângela Tallarico Adorno, Filipe Vasconcelos Ferreira and Guilherme Peixoto

Fermentation 2024, 10(11), 586; https://doi.org/10.3390/fermentation10110586 - 14 Nov 2024

Abstract

In this study, an upflow anaerobic packed-bed reactor (UAPB) produced biobutanol from the main byproduct of biodiesel plants, commonly known as glycerol. Currently, butanol production is mostly limited to pure cultures and sterilized feedstocks. Using glycerol wastes from biodiesel production demands a new [...] Read more.

In this study, an upflow anaerobic packed-bed reactor (UAPB) produced biobutanol from the main byproduct of biodiesel plants, commonly known as glycerol. Currently, butanol production is mostly limited to pure cultures and sterilized feedstocks. Using glycerol wastes from biodiesel production demands a new paradigm because sterilization is not economically feasible for the elevated amount of glycerol generated by the biodiesel industry. Different microbial consortia were evaluated as inoculum sources to convert glycerol to butanol. In the first stage, operations were carried out with an average organic loading rate (OLR) of 13 g COD L⁻¹ d⁻¹. Kefir grains, sucrose auto-fermentation consortium, and heat-treated anaerobic sludge produced 16.7, 48.5, and 12.8 mg of butanol per gram of chemical oxygen demand (COD), respectively. Besides butanol production, a significant amount of ethanol (241.5 mg g⁻¹ COD), acetate (30.3 mg g⁻¹ COD), and butyrate (183.4 mg g⁻¹ COD) were generated with glycerol processed by sucrose auto-fermentation consortium. In the second stage, the organic loading rates of 6.5, 13.0, and 26.0 g COD L⁻¹ d⁻¹ were applied to the UAPB reactor inoculated with sucrose auto-fermentation consortium. The OLR of 13.0 g COD L⁻¹ d⁻¹ yielded the highest production of butanol (41.5 mg g⁻¹ COD) and generated other valuable co-products such as butyrate (246.1 mg g⁻¹ COD), acetate (37.3 mg g⁻¹ COD), and propionate (19.6 mg g⁻¹ COD). Full article

(This article belongs to the Special Issue Microbial Fermentation of Organic Wastes for Production of Biofuels and Biochemicals 2.0)

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15 pages, 1376 KiB

Open AccessArticle

Effect of Commercial Bioprotective Lactic Cultures on Physicochemical, Microbiological, and Textural Properties of Yogurt

by Elói Duarte de Mélo, Pedro Ivo Soares e Silva, Suelma Ferreira do Oriente, Renata Duarte Almeida, Julia Morais Pessoa, Kepler Borges França, Thaísa Abrantes Souza de Gusmão, Rennan Pereira de Gusmão, Hugo M. Lisboa Oliveira and Amanda Priscila Silva Nascimento

Fermentation 2024, 10(11), 585; https://doi.org/10.3390/fermentation10110585 - 14 Nov 2024

Abstract

The present study investigated the effects of the commercial biopreservatives FRESHQ-11 (Lactobacillus rhamnosus), labeled as F, and HOLDBAC YM-B LYO 100 DCU (Lactobacillus rhamnosus and Propionibacterium freudenreichii subsp. shermanii), labeled as H, at different dosages on the pH, titratable [...] Read more.

The present study investigated the effects of the commercial biopreservatives FRESHQ-11 (Lactobacillus rhamnosus), labeled as F, and HOLDBAC YM-B LYO 100 DCU (Lactobacillus rhamnosus and Propionibacterium freudenreichii subsp. shermanii), labeled as H, at different dosages on the pH, titratable acidity (%), fungal inhibition, and textural parameters of yogurt during 28 days of storage at 7 ± 1 °C. The study compared these biopreservatives with yogurt containing only the chemical preservative potassium sorbate at the maximum allowed concentration (C1) and yogurt without any chemical preservatives (C2), with the goal of identifying alternatives to reduce or replace potassium sorbate. Yogurts were formulated with biopreservatives at concentrations of 0.1% and 0.2% (v/v) and with potassium sorbate at 0.015% and 0.03%. The results indicated that yogurts containing biopreservatives had significantly lower pH and higher titratable acidity (%) than C2 (p < 0.05). Syneresis significantly decreased over the 28-day storage period at 7 ± 1 °C (p < 0.05). Additionally, yogurts with bioprotective cultures exhibited significantly lower textural parameters (p < 0.05) compared to C1 and C2. This study underscores the potential of biopreservatives as viable replacements for potassium sorbate, with these formulations being comparable to C1 in inhibiting molds and yeasts, particularly when L. rhamnosus was used at 0.2% v/v. This finding is promising for future pilot and industrial-scale applications. Full article

(This article belongs to the Special Issue Applications of Lactic Acid Bacteria in Fermented Foods and Beverages)

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12 pages, 2219 KiB

Open AccessArticle

Machine Learning Method (Decision Tree) to Predict the Physicochemical Properties of Premium Lebanese Kishk Based on Its Hedonic Properties

by Ossama Dimassi, Youmna Iskandarani, Houssam Shaib, Lina Jaber and Shady Hamadeh

Fermentation 2024, 10(11), 584; https://doi.org/10.3390/fermentation10110584 - 14 Nov 2024

Abstract

This study sets the criteria of high-grade kishk (a dried fermented cereal–milk product) based on sensory attributes. For this, kishk samples were collected, and physicochemical attributes and sensory attributes were recorded. Subsequently, Spearman’s correlation between sensory properties and physicochemical properties was calculated. A [...] Read more.

This study sets the criteria of high-grade kishk (a dried fermented cereal–milk product) based on sensory attributes. For this, kishk samples were collected, and physicochemical attributes and sensory attributes were recorded. Subsequently, Spearman’s correlation between sensory properties and physicochemical properties was calculated. A decision tree [DT] was applied with the mean total sensory score [MTSC] as the dependent factor to establish the physicochemical factor/s upon which the different kishk grades were set. To compare the physiochemical attributes of the different grades, the general linear model was applied. Moisture content is negatively and significantly correlated with most sensory attributes. Titratable acidity [TA] is positively and significantly correlated with most sensory attributes. The DT analysis showed that TA was the classifying factor [p = 0.01], and accordingly, grade A [TA ≥ 4.56], grade B [2.50 < TA < 4.56], and grade C [TA ≤ 2.50] kishk data were established, showing MTSC values of 6.32 ± 0.32, 5.26 ± 0.36, and 4.40 ± 0.20, respectively. Applying DT analysis with kishk grades as independent variables, pH was a classifying factor, with 3.95 as the cutoff point. Moisture [p = 0.018], the protein-to-fat ratio [P:F] [p = 0.027] and pH [p < 0.001] differ significantly between the different kishk grades. Accordingly, the criteria for grade A kishk are TA ≥ 4.56, pH ≤ 3.95, moisture < 4%, P:F < 2.03, and particle density < 1489. The low pH and moisture content render it a shelf-stable high-acid food. Full article

(This article belongs to the Special Issue Analysis of Quality and Sensory Characteristics of Fermented Products)

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17 pages, 659 KiB

Open AccessReview

The Role of Yeast in the Valorisation of Food Waste

by Laura Murphy and David J. O’Connell

Fermentation 2024, 10(11), 583; https://doi.org/10.3390/fermentation10110583 - 13 Nov 2024

Abstract

The implementation of the circular bioeconomy is now widely accepted as a critical step towards reducing the environmental burden of industrial waste and reducing the impact of this waste on climate change. The valorisation of waste using microorganisms is an attractive and fast-developing [...] Read more.

The implementation of the circular bioeconomy is now widely accepted as a critical step towards reducing the environmental burden of industrial waste and reducing the impact of this waste on climate change. The valorisation of waste using microorganisms is an attractive and fast-developing strategy capable of achieving meaningful improvements in the sustainability of the biotechnology industry. Yeasts are a powerful chassis for developing valorisation strategies and key opportunities. Thus, this study examines how waste from the food sector can be effectively targeted for valorisation by yeast. Yeasts themselves are critically important elements in the production of food and brewing, and thus, the valorisation of waste from these processes is further reviewed. Policy and regulatory challenges that may impact the feasibility of industrial applications of yeast systems in the valorisation of food waste streams are also discussed. Full article

(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 5th Edition)

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13 pages, 852 KiB

Open AccessArticle

Preliminary Evaluation of Watermelon Liquid Waste as an Alternative Substrate for Microalgae Cultivation: A Circular Economy Approach to the Production of High-Value Secondary Products by Chlorella vulgaris, Scenedesmus sp., Arthrospira platensis, and Chlamydomonas pitschmanii

by Paolina Scarponi, Lorenzo Fontana, Francesco Bertesi, Veronica D’Eusanio, Lorenzo Tassi and Luca Forti

Fermentation 2024, 10(11), 582; https://doi.org/10.3390/fermentation10110582 - 12 Nov 2024

Abstract

In Italy, watermelon cultivation spans 9510 hectares, with production levels largely influenced by seasonal market demand. As a result, surplus watermelon left unsold by September often remain in the fields, where they decompose naturally and go to waste. A chemical analysis of the [...] Read more.

In Italy, watermelon cultivation spans 9510 hectares, with production levels largely influenced by seasonal market demand. As a result, surplus watermelon left unsold by September often remain in the fields, where they decompose naturally and go to waste. A chemical analysis of the watermelon liquid fraction waste (WW) indicates a high carbohydrate concentration, highlighting the potential for biotechnological valorization of this waste stream, converting it into lipids or exopolysaccharides (EPSs). This study investigates the feasibility of utilizing WW as an alternative growth substrate for microalgae, aligning with circular economy principles and advancing sustainable agricultural practices. By repurposing agricultural byproducts, this research supports biorefinery objectives, aiming to convert biomass into high-value secondary products, including biofuels, pigments, and nutraceuticals. Scenedesmus and Chlorella strains demonstrated promising growth and adaptability in WW, achieving biomass yields of 0.95 ± 0.07 g L⁻¹ and 0.37 ± 0.02 g L⁻¹, respectively, with a significant EPS production observed as medium gelation. Although lipid accumulation was limited in this case by the WW substrate, the lipid profiles of both strains were distinctively altered, notably lacking linolenic acid. Full article

(This article belongs to the Special Issue The Future of Fermentation Technology in the Biorefining Process: 2nd Edition)

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16 pages, 6150 KiB

Open AccessArticle

Lactic Acid Production from Distiller’s Dried Grains Dilute Acid Hydrolysates

by Greta Naydenova, Petya Popova-Krumova, Svetla Danova and Dragomir Yankov

Fermentation 2024, 10(11), 581; https://doi.org/10.3390/fermentation10110581 - 12 Nov 2024

Abstract

Lactic acid (LA) is an important chemical with diverse applications in various industries. LA can be produced by the fermentation of different substrates by many microorganisms such as bacteria, fungi, yeasts, and algae. Lactic acid bacteria (LAB) are generally accepted as the main [...] Read more.

Lactic acid (LA) is an important chemical with diverse applications in various industries. LA can be produced by the fermentation of different substrates by many microorganisms such as bacteria, fungi, yeasts, and algae. Lactic acid bacteria (LAB) are generally accepted as the main producers of LA. A distinct characteristic of LAB is the complexity of the fermentation media. Distiller’s dried grains with solubles (DDGS), a by-product from bioethanol production, represent a promising substitute for costly sugars in the nutrition media for LA production. In the present paper, the possibility of using dilute acid DDGS hydrolysates as a substrate for LA fermentation was investigated. The influence of different factors (acid concentration, time, pressure, solid-to-liquid ratio) on the reducing sugars (RS) obtained was studied. Additional enzyme hydrolysis was carried out to increase RS content in the hydrolysates. LA production from hydrolysates without and with control of the pH during fermentation was monitored and compared with lactose as a substrate. Inhibition of the process was observed in both substrates in the absence of pH control which was overcome in the case of pH control. A mathematical model based on the Verhulst and Ludeking–Piret equations was proposed and tested, showing very good agreement with experimental data. Full article

(This article belongs to the Special Issue Biomass Conversion, CO₂ Valorisation and Power-to-X: Fermentation Chemicals and Fuels)

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