Fermentation, Volume 10, Issue 4 (April 2024) – 49 articles

Studying non-Saccharomyces yeasts as bio-protectors can help find new alternatives to the chemical additive SO₂ in winemaking. The present article evaluates the effect of two native yeasts, Candida oleophila and Candida boidinii, as potential bio-protectors to replace SO₂ during the production of Sauvignon Blanc wine. Fermentation was conducted on simple and mixed inoculum at two concentrations, 1 × 10⁶ and 1 × 10⁷ cells/mL. We monitored the population of deterioration microorganisms, including lactic acid bacteria (LAB), acetic acid bacteria (AAB), and Brettanomyces bruxellensis (BB), apart from the final chemical and volatile composition of the wine. The results were compared with fermentations protected with SO₂, where Candida oleophila yeast was more effective against lactic acid bacteria, whereas Candida boidinii was more effective against acetic acid bacteria and Brettanomyces bruxellensis; meanwhile, the fermentations with the initial inoculum of 1 × 10⁷ cells/mL showed better results than those with an inoculum of 1 × 10⁶ cells/mL. Bio-protector use did not negatively affect wine quality, equaling the effectiveness of SO₂ for spoilage microorganism inhibition. This study reveals for the first time the potential of Candida oleophila and Candida boidinii yeasts as bio-protectors in microbiological wine stabilization. Full article

The ongoing occurrence of foodborne diseases and the imperative need for efficient spoilage and pathogen control in food products constitute a critical challenge for the food industry. The rising demands of consumers for safe, healthy, and clean-label food products have led to an increased interest in natural antimicrobial alternatives. Lactic acid bacteria (LAB) have proven their value in the food industry in recent years, also in reason of their antagonistic properties against undesired microbes and their significant related protechnological attributes. The natural antimicrobial compounds produced by LAB exhibit inhibitory effects on pathogens and effectively inhibit the activities of food spoilage-related organisms. Applying secondary metabolites of LAB, notably bacteriocins, organic acids, and others, has found commercial utility across multiple food sectors, effectively preventing the proliferation of undesirable microorganisms and simultaneously enhancing the sensory properties and overall quality of various food products. This review comprehensively explores the natural microbial compounds produced by LAB, specifically focusing on their antimicrobial action in supporting effective and sustainable microbial management. Additionally, it highlights their strategic application across various technological contexts within the food industry. Full article

The use of antibiotics to promote growth and prevent diarrhea in livestock production has raised concerns about the emergence of antibiotic-resistant bacteria. Probiotics, live microorganisms that confer health benefits, have been proposed as alternatives to antibiotics. In this study, we produced and characterized a downgraded maple syrup-based feed supplement containing Bacillus velezensis FZB42 as a potential synbiotic for animal nutrition. An optimized fermentation medium was developed through a central composite design to produce B. velezensis FZB42 at both the laboratory and pilot scale, reaching a concentration of 6.15 ± 0.46 × 10⁹ CFU/mL. Subsequently, B. velezensis FZB42 was incorporated into a protective whey permeate matrix and spray-dried, resulting in a 31.4% yield with a moisture content of 4.38%. The survival of B. velezensis FZB42 in a simulated gastrointestinal tract was evaluated using the TIM-1 system, revealing a survival rate of 16.05% after passage through the gastric, duodenal, jejunal, and ileal compartments. These findings highlight the possibility of B. velezensis FZB42 being an economically viable and possibly functional synbiotic supplement and effective alternative to antibiotic growth promoters in livestock production. Full article

Marine microalgae offer a sustainable alternative source for the human diet’s essential omega-3-fatty acids, including docosahexaenoic acid (DHA, C22:6) and eicosapentaenoic acid (EPA, C20:5). However, none of them can produce DHA and EPA in a nutritionally balanced ratio of 1:1. As shown recently, the phototrophic co-cultivation of the golden-brown microalgae Tisochrysis lutea (DHA producer) with the green microalgae Microchloropsis salina (EPA producer) can provide microalgae biomass with a balanced DHA-to-EPA ratio with increased productivity compared to monocultures. This study evaluates whether other golden-brown (Isochrysis galbana) and green microalgae (Nannochloropsis oceanica, Microchloropsis gaditana) can enable the phototrophic batch production of omega-3 fatty acids in a nutritionally balanced ratio in co-culture. All co-cultivations applying a physically dynamic climate simulation of a repeated sunny summer day in Australia in LED-illuminated flat-plate gas lift photobioreactors resulted in increased biomass concentrations compared to their respective monocultures, achieving balanced DHA-to-EPA ratios of almost 1:1. Using urea instead of nitrate as a nitrogen source increased the EPA content by up to 80% in all co-cultures. Light spectra measurements on the light-adverted side of the photobioreactor showed that increased biomass concentrations in co-cultures could have been related to enhanced light use due to the utilization of different wavelengths of the two microalgae strains, especially with the use of green light (500–580 nm) primarily by golden-brown microalgae (I. galbana) and orange light (600–620 nm) predominantly used by green microalgae (N. oceanica). Phototrophic co-cultivation processes thus promise higher areal biomass yields if microalgae are combined with complimentary light-harvesting features. Full article

Nejayote, the wastewater from the nixtamalization of maize, is difficult to biodegrade due to its abundant calcium content; low levels of nitrogen, phosphorus, and easily assimilable sugars; elevated pH; and high chemical oxygen demand (COD). The aim of the present study was to isolate microorganisms capable of utilizing filtered nejayote (NEM) as the only source of carbon for growth and to test the best microorganism for the bioremediation of this wastewater by lowering the level of pH and COD. Of the 15 strains of microorganisms tested, Rhodotorula mucilaginosa LCRE was chosen and identified using molecular techniques. Subsequently, its growth kinetics were characterized during cultivation in unenriched NEM (control) and NEM enriched with nitrogen and phosphorus salts. R. mucilaginosa LCRE showed a greater growth (6.9 ≤ X ≤ 8.9 g L⁻¹), biomass yield (0.33 ≤ Y_X/S ≤ 0.39 g g⁻¹), and specific growth rate (0.748 ≤ µ ≤ 0.80 day⁻¹) in the enriched versus control NEM (X = 6.55 g L⁻¹, Y_X/S = 0.28 g g⁻¹, and µ = 0.59 day⁻¹). However, a higher total sugar consumption (94.98%), better COD removal efficiency (75.5%), and greater overall COD removal rate (1.73 g L⁻¹ h⁻¹) were found in the control NEM. Hence, R. mucilaginosa LCRE holds promise for the efficient bioremediation of nejayote without costly pretreatments or nutrient supplementation. Full article

Wine fermentation is a biochemical process carried out by a microbial consortium already present in the vineyard, including different species of fungi and bacteria that are in an ecological relationship with each other, so that their sequential growth causes the transformation of grape must into wine. Among the fungi, the unicellular ones, yeasts, stand out, including Saccharomyces cerevisiae, which is mainly responsible for driving alcoholic fermentation, as do other species present from the beginning of fermentation, known as non-Saccharomyces yeasts. These yeasts were previously considered harmful and undesirable; however, their role has recently been re-evaluated, mainly because they can provide products and effects that are of great value in achieving a quality final product. In this review, we discuss the role of non-Saccharomyces wine yeasts, firstly with regard to their biocontrol activity both on the grapes and during the vinification process and secondly with regard to their ability to produce enzymes, especially depolymerising ones. In this context, the possible biotechnological applications of these non-Saccharomyces yeasts to improve the health and quality of grape and wine production are addressed. Full article

Mezcal is a drink made in Mexico, the production of which generates vinasses with a high content of organic matter (OM) that is not utilized. However, these residues have the potential to be drawn upon in dark fermentation (DF) processes to obtain biogas rich in biohydrogen, biomethane, and volatile fatty acids (VFAs) with the potential to become biofuels. In the present work, the effect of reaction time (RT) and organic load (OL) was assessed based on the efficiency of removing OM, the production of VFAs, and the generation and composition of biogas in a process of DF fed with mezcal vinasses. The results show that increasing the RT and decreasing the OL increases COD removal but decreases biohydrogen production. The maximum production of H₂ (64 ± 21 NmL H₂/L_reactor) was obtained with the lowest RT (1 d) and the highest OL (13.5 gCODm³d⁻¹), while the highest accumulation of VFAs (2007 ± 327 mg VFA/L) was obtained with an RT of 3 d. It was determined that RT and OL are key parameters in DF processes for biohydrogen and VFA production. Full article

The skins of Vitis vinifera species contain 3-glucosyl anthocyanins (3G), but some non-vinifera species, such as ‘Yama Sauvignon’ (YS), contain a large amount of 3,5-diglucosyl anthocyanins (35DG), and the behavior of anthocyanin coloration with respect to pH is quite different. The anthocyanins of YS showed a very weak color at a pH of 3 or higher but a very strong color below a pH of 3. Furthermore, when we investigated the effect of co-pigmentation in commercially available wines, we found that YS red wine contained a large amount of co-pigmented anthocyanins, and even wine aged for about 4 years contained a large amount of co-pigmented anthocyanins. Due to concerns regarding disease resistance, many hybrid varieties of V. vinifera and non-vinifera species have been bred, but it is important to take these special properties of 35DG into consideration when producing wine. Full article

Mulberry leaves are rich in nutrients but contain anti-nutrient factors that hinder their digestion and absorption. Feeding animals with mulberry leaves directly could harm their health. The microbial fermentation of mulberry leaves could reduce their anti-nutritional factors’ content and improve their nutritional value. Sequencing and analyzing mulberry leaves before and after fermentation showed that fermentation increased the relative abundance of Pediococcus, Bradyrhizobium, Hydrotalea, and Rhodanobacteria, and decreased that of Enterobacter. Fermentation improved the quality of mulberry leaves by rebuilding the bacterial community. Finishing pigs were raised on fermented mulberry leaves (FML), and their carcass performance, meat quality, economic benefits, and gut microbiome were evaluated. FML had no negative impact on pig carcass performance, meat quality, and antioxidant capacity, and could somewhat improve the economic benefits. FML decreased the relative abundance of Proteobacteria in the colon and Streptococcus in the feces, and increased that of Actinobacteria (cecum, colon, feces) and Prevotella (colon). The gut core microorganisms in the FML group were mainly enriched with Actinobacteria, Bifidobacterium, Bifidobacteriaceae, Bifidobacteriales, and other beneficial microorganisms. Dietary FML reduced ammonia, indole, and skatole contents in the feces. In conclusion, FML reshaped the gut microbiota without negatively affecting pig product performance, produced cleaner waste, and improved environmental protection and sustainability, making it an attractive prospective feed for pigs. Full article

This study was conducted to investigate the effects of different strains and wheat bran on the fermentation quality, antioxidant activity, and bacterial community of mulberry leaf silage. Mulberry leaves were ensiled with Pediococcus acidilactici and Pediococcus pentosaceus (A), Bacillus subtilis and Bacillus licheniformi (DK), and Pediococcus acidilactici, Pediococcus pentosaceus, Bacillus subtilis, and Bacillus licheniformi (AK). Each treatment was supplemented with 10% wheat bran (fresh matter basis), and the strains were added in equal proportions for 7 days. The results indicated that the DK and AK groups exhibited higher dry matter (DM) content compared to the A group (p < 0.05). The A group (37.25 mg/g DM) and AK group (34.47 mg/g DM) demonstrated higher lactic acid content and lower pH (<4.40). Furthermore, the DK group had a significantly higher acetic acid content compared to the AK group (p < 0.05). Additionally, both the A and AK groups exhibited lower levels of ammonia-N content than the DK group (p < 0.05). The number of yeasts, molds, and coliform bacteria were low in mulberry leaf silage. Moreover, the antioxidant activity in the fermentation groups increased, with higher relative abundance of beneficial bacteria, Lactococcus and Lactobacillus, in the AK group. In summary, the AK group was observed to enhance fermentation quality and antioxidant capacity, leading to the establishment of a favorable microbial community composition. Full article

Inhibiting homoacetogens is one of the main challenges in fermentative hydrogen production because these hydrogen consumers have similar growth features to hydrogen producers. Homoacetogens have been related to the excessive accumulation of biomass in fermentative reactors. Therefore, a suitable food/microorganism ratio has the potential to minimize the homoacetogenic activity. In this work, the specific organic loading rate (SOLR) was controlled in two fermentative fixed-bed up-flow reactors through scheduled biomass discharges. Reactors were differentiated by the bed arrangement, namely, packed and structured conformation. The SOLR decay along the time in both reactors was previously simulated according to the literature data. The volume and volatile suspended solids (VSS) concentration of discharges was estimated from the first discharge, and then additional discharges were planned. Biomass discharges removed 21% of the total biomass produced in the reactors, maintaining SOLR values of 3.0 ± 0.4 and 3.9 ± 0.5 g sucrose g⁻¹ VSS d⁻¹ in the packed-bed and structured-bed reactors, respectively. Such a control of the SOLR enabled continuous and stable hydrogen production at 2.2 ± 0.2 L H₂ L⁻¹ d⁻¹ in the packed-bed reactor and 1.0 ± 0.3 L H₂ L⁻¹ d⁻¹ in the structured-bed one. Controlling biomass was demonstrated to be a suitable strategy for keeping the continuous hydrogen production, although the fermentative activity was impaired in the structured-bed reactor. The homoacetogenic was partially inhibited, accounting for no more than 30% of the total acetic acid produced in the reactor. Overall, the high amount of attached biomass in the packed-bed reactor provided more robustness to the system, offsetting the periodic suspended biomass losses via the planned discharges. Better characterizing both the VSS composition (aiming to differentiate cells from polymeric substances) and the bed hydrodynamics could be useful to optimize the online SOLR control. Full article

Traditional sparkling wines are produced in a two-step sequence of alcoholic fermentations, followed by extended aging which is an influential factor for the final aroma profile. Traditionally, the second fermentation and aging are conducted in bottles over a minimum of 18 months, resulting in an aroma profile which is shaped by oxidative secondary metabolites like aldehydes, acids and fatty acid esters. In this study, a total of 29 traditional commercial sparkling wines from the categories Champagne, Cava, California Champagne, and others (Prosecco and Cremant) were analyzed. The objective was to determine the impact of microbial activity on the stylistic characteristics of traditional sparkling wines and allow winemakers to reproduce the specific fermentation conditions. The results indicate that malolactic fermentation plays an important role in Champagne and some Cavas, but not in the other sparkling wine categories. The metabolic activity of lactic acid bacteria results in an altered acid profile, amino acid utilization, and aroma production. While primary fermentation esters like phenylethyl acetate and isoamyl acetate are significantly reduced in Champagne and Cava, aroma compounds from secondary microbial activity like ethyl lactate and 2-acetyl-1-pyrroline are increased. This underlines the importance of diverse microbial activity of the characteristic style of traditional sparkling wines. Full article

Patchoulol is a natural sesquiterpene alcohol with extensive applications in cosmetics and pharmaceuticals. In this study, we first constructed the synthesis pathway of patchoulol in Saccharomyces cerevisiae by expressing the patchoulol synthase PTS gene using the strong promoter GAL1. Afterward, the metabolic flux of the precursor was enhanced by strengthening the mevalonate pathway and balancing the precursor competition pathway, resulting in a 32.74-fold increase in patchoulol production. Subsequently, the supply of acetyl-CoA in yeast was increased by modifying transcriptional regulators and modulating the acetyl-CoA pathway, and the titer of patchoulol reached 155.94 mg/L. Finally, optimization of the fermentation conditions resulted in a titer of 195.96 mg/L in the shake flasks. Further, batch-fed fermentation in a 5 L bioreactor yielded 1.95 g/L. This work accelerated the development of a microbial cell factory for the production of patchoulol. Full article

Effective sulfur dioxide (SO₂) management is crucial in winemaking to minimize oxidative changes in wine flavor during storage. This study explored the impact of various SO₂ management techniques on Solaris white wine’s flavor components and sensory properties. Five treatments were administered: ‘SO₂ in juice’ (50 mg/L SO₂ added to juice pre-fermentation), ‘Control’ (60 mg/L SO₂ added post-fermentation), ‘Low SO₂’ (50 mg/L SO₂ post-fermentation), ‘High SO₂’ (100 mg/L SO₂ post-fermentation), and ‘No SO₂’ (no SO₂ added). The ‘Control’ followed a standard procedure, in which the achieved level of free sulfite is measured and extra SO₂ added to reach the recommended level of free sulfite for the pH of the wine. Here, 50 + 10 mg/L was added. Volatile compounds were analyzed using dynamic headspace sampling coupled with gas chromatography–mass spectrometry after 0, 3, 6, and 12 months of storage. Sensory evaluation by a trained panel after 12 months revealed stronger perceptions of ‘overall impression’, ‘chemical’, ‘bitter’, ‘overripe fruit’, and ‘honey’ notes in the ‘No SO₂’ and ‘SO₂ in juice’ wines. The data underscore the significant influence of SO₂ management on the flavor stability of Solaris white wines, emphasizing the need for strategic SO₂ interventions during winemaking to enhance sensory quality over time. Full article

This study provides a comprehensive investigation of lactic acid bacteria (LAB) isolated from Argentinean Capsicum annum L. This research covers important aspects, including genotypic characterization, bacterial stress tolerance, adhesion ability, safety evaluation, and functional and technological properties. The predominant isolates were identified as Lactilactobacillus curvatus and Lactiplantibacillus plantarum. A Rep-PCR analysis grouped the isolates into 11 clonal groups. Lp. plantarum LVP 40 and LV 46, Levilactobacillus brevis LVP 41, Pediococcus pentosaceus LV P43, and Lt. curvatus LVP44 displayed both safety and resilience against adverse conditions such as a slow pH, bile, and simulated gastric and intestinal juices. Moreover, the LAB strains exhibited high hydrophobicity and auto-aggregation percentages, NaCl tolerance, and a substantial acidifying capacity. LAB supernatants demonstrated promising surfactant and emulsifying properties. Likewise, they differentially inhibited Staphylococcus aureus and Pseudomonas aeruginosa biofilms, showcasing their potential as antipathogenic agents. Noteworthily, some strains displayed considerable co-aggregation with these pathogens, and several isolates showed an effective antimutagenic and detoxifying power, further emphasizing their multifaceted capabilities. Five pepper bacterial strains showcased beneficial properties, suggesting their potential for gut health enhancement. In summary, these LAB strains hold promise as vegetable fermentation starters, contributing to food safety and versatile applications in food science. Full article

Mammalian hemoglobins (HB) are a kind of heme-binding proteins that play crucial physiological roles in various organisms. The traditional techniques employed for the extraction of HB are expensive and time-consuming, while the yields of mammalian HB in previous reports were quite low. The industrial Pichia pastoris is a highly effective platform for the secretory expression of heterologous proteins. To achieve efficient secretory expression of HB in P. pastoris, multiple strategies were applied, including the selection of a suitable host, the screening of optimal endogenous signal peptides, the knockout of VPS10, VTH1, and PEP5, and the co-expression of Alpha-Hemoglobin Stabilizing Protein (AHSP). In addition, the conditions for producing HB were optimized at shaking-flask level (BMMY medium with 100 mg/L of hemin, 2% methanol, and 24 °C). Based on these conditions, the higher titers of bovine hemoglobin (bHB, 376.9 ± 13.3 mg/L), porcine hemoglobin (pHB, 119.2 ± 7.3 mg/L), and human hemoglobin (hHB, 101.1 ± 6.7 mg/L) were achieved at fermenter level. The engineered P. pastoris strain and comprehensive strategies can also be applied to facilitate the synthesis of other high-value-added hemoproteins or hemoenzymes. Full article

High-fiber, low-cost agricultural byproducts offer a sustainable alternative for mitigating the competition for crops between humans and livestock. Pigs predominantly utilize dietary fibers through the process of microbial fermentation within the gut. This study explored the gut microbiota and the capacity for carbohydrate degradation in 30 individual Lantang pigs, a breed indigenous to China. Through metagenomic analysis, a total of 671 metagenome-assembled genomes (MAGs) were assembled and assigned into 14 bacterial and 1 archaeal phylum, including 97 species from uncultured microbes. The phylum with the highest abundance were identified as Bacillota_A, Bacteroidota, and Bacillota. Remarkably, the investigation revealed nearly 10,000 genes implicated in the degradation of carbohydrates, with a pronounced prevalence within five principal bacterial genera: Prevotella, Cryptobacteroides, Gemmiger, Vescimonas, and Faecousia. Additionally, 87 distinct types of carbohydrate-degrading enzymes were exclusively identified within the gut microbiota of the Lantang pig. These insights not only enhance our understanding of the microbial diversity specific to native Chinese pig breeds but also augment the body of research regarding porcine fiber degradation capabilities. The implications of this study are twofold: it provides strategic directions for optimizing feed efficiency and reducing breeding costs, and it furnishes an expanded gene pool for the microbial synthesis of industrial enzymes in the future. Full article

This article deals with the analysis of the condensates which are formed from fermentation gases during the fermentation of grape must. The experiment was divided into two parts. In the first part, the evolution of the individual volatiles was monitored throughout the whole fermentation process of the Riesling variety. In the second part, the condensates from three different grape varieties (Riesling, Merlot, Sauvignon blanc) were investigated and the total content of the selected volatile substances was measured at the end of the fermentation. Attention was focused on the measurements using a GC-MS (gas chromatography-mass spectrometry) for the volatile substances: isoamyl alcohol, isobutyl alcohol, 1-propanol, ethyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, acetaldehyde, acetic acid, and acetoin. In addition, changes in the alcohol content of the condensate, with respect to the fermentation phase, were analysed. From the results of part 1, the quantity of the substances under investigation produced during fermentation was determined. The highest concentration of flavour compounds was during the fourth and fifth days of fermentation. The most dominant substance was isoamyl alcohol with a concentration of 1267 mg⁻¹.The results of part 2 led to a comparison of the overall profile of volatiles between the varieties. The results showed that the condensates have both a high content of volatile substances and of alcohol. It was also shown that the Sauvignon blanc variant had the highest number of volatile compounds in the representation. The Merlot and Riesling variants were very similar. This product has an exceptionally high potential for further use in the wine or food industry. Full article

This study investigates the impact of varying concentrate levels in the diets of Angus beef cattle on their performance, nutrient digestion, and metabolism during the growth (7 to 12 months) and fattening (13 to 30 months) phases. Fifteen Angus steers were continuously fed and divided into low-concentrate (L) and high-concentrate (H) groups based on the fattening period and dietary formulations. Throughout each 9-week trial phase, a comprehensive range of parameters was systematically measured, including dry matter intake (DMI), average daily gain (ADG), gain-to-feed ratio (G/F), blood parameters, rumen fluid composition, and microbial diversity. In the fattening phases, an increase in concentrate levels resulted in a significant rise in the cattle’s DMI. Although there was a minor increase in ADG compared to the growing phases, this increase was not statistically significant. The efficiency of nitrogen (N) utilization in the cattle decreased, accompanied by a significant reduction in the apparent digestibility of nutrients. Ruminal fermentation produced more energy substances; however, there was a notable decrease in the abundance of fiber-decomposing microbes (such as the NK4A214_group, Ruminococcus, Papillibacter, and Acetitomaculum) and a significant increase in the abundance of starch-degrading microbes (including Bacteroidota and Prevotellaceae). Additionally, there was a significant reduction in the abundance of immune system-related functional pathways. This suggests that high-concentrate fattening does not necessarily lead to improved growth performance and may negatively affect metabolic health and nutrient digestion. Full article

This study evaluated the effects of two chemical additives or a microbial inoculant on chemical composition and DM losses in whole-plant soybean silage. One-hundred and twenty mini-silos were used in a completely randomized design experiment with the following treatments: water without chloride (control, CON); a microbial inoculant (INO); a chemical additive containing 35–45% formic acid (FA type); and another chemical additive containing 50–60% propionic acid (PA type). Data were analyzed using mixed models of SAS, and treatment differences were evaluated by the following orthogonal contrasts: C1 = CON vs. additives (INO + FA type + PA type); C2 = INO vs. chemical additives (FA type + PA type); and C3 = PA type vs. FA type. Silage pH and ammonia nitrogen concentration were decreased, and concentrations of lactic acid and acetic acid were increased with additives. Counts of lactic acid bacteria were higher in silages with INO than with chemical additives. DM recovery increased with FA type and PA type. Additives increased DM and CP concentrations. Silage A-fraction proportion was greater with additives. Additives, particularly FA type and PA type, improved chemical composition and fermentative profile and reduced undigestible proportions of protein in whole-plant soybean silage. Chemical additives were more effective in reducing silage DM losses than INO. Full article

Crypthecodinium cohnii is a marine microalga that can accumulate high amounts of polyunsaturated fatty acids (PUFAs) and thus replace conventional routes of fish oil production. They are associated with the destruction of marine resources and multiple downstream/purification complications. The major drawbacks of using C. cohnii for industrial-scale production are associated with low PUFA productivity. One of the means of increasing the PUFA synthesis rate is to maintain the medium component concentrations at optimal values throughout cultivation, thus increasing PUFA production efficiency, which can result in the successful transfer of the process to pilot and/or industrial scale. The goal of the present research was to develop techniques for increasing the efficiency of PUFA production via C. cohnii cultivation. Multiple experiments were carried out to test and fine-tune the cultivation medium composition and oxygen transfer factors. The biomass yields from individual components, yeast extract, sea salts, and glucose amounted to 5.5, 0.65, and 0.61 g·g⁻¹, respectively. C. cohnii cell susceptibility to mechanical damage was experimentally evaluated. Power inputs of <276.5 W/m³ did not seem to promote cell destruction when Pitched-blade impellers were used. The obtained cultivation conditions were shown to be efficient in terms of increasing the biomass productivity and the omega-3 fatty acid content in C. cohnii. By using the applied methods, the maximal biomass productivity reached 8.0 g·L⁻¹·day⁻¹, while the highest obtained biomass concentration reached 110 g·L⁻¹. A steady increase in the concentration of PUFAs during cultivation was observed from the FTIR data. Full article

Human epidermal growth factor (hEGF) holds significant importance in the fields of medicine and cosmetics. Therefore, it becomes imperative to develop a highly efficient fermentation system for hEGF production. In this study, a stable hEGF-secreting expression strain was created by integrating the hEGF gene into the genome of Escherichia coli (E. coli) BL21, and an immobilized fermentation system was developed based on biofilm to facilitate continuous hEGF production. After optimization of fermentation conditions and gene dosage, the production of hEGF was increased from 13.9 mg/L to 52.4 mg/L in free-cell fermentation. Moreover, genetic modifications targeting dgcC, csgD, bcsA, and bcsB proved to enhance biofilm formation. When the bcsB was overexpressed in BL21-hEGF-C5, the biofilm-forming ability was enhanced by 91.1% and the production of hEGF was increased by 28% in biofilm-immobilized continuous fermentation. In conclusion, this study successfully confirms the feasibility of continuous hEGF production through the biofilm system of E. coli, providing valuable insights for the development of other proteins in the field of continuous biomanufacturing. Full article

This study examined the impact of sodium propionate concentration (0–40 g/L) on the methanogenic archaea in an inoculum which was cultured in basal nutrient medium, exploring its mechanisms and nonlinear stress intensity. The results indicated that at low concentrations, propionate-maintained homeostasis of the anaerobic digestion (AD) system and enriched Methanosaeta. However, when the concentration exceeded 16 g/L, the stability of the AD system was disrupted. The methanogenic pathway shifted towards a predominantly hydrogenotrophic pathway, resulting in a significant increase in methane yield. Below concentrations of 28 g/L, the AD system gradually enhanced its ability to utilize propionate in an orderly manner. At concentrations of 24–28 g/L, genera (e.g., Advenella and Methanosarcina) were enriched to adapt to the high-VFA environment. This was accompanied by a significant upregulation of genes related to the methylotrophic and hydrogenotrophic pathways, effectively mitigating propionate inhibition and enhancing methanogenesis. Conversely, excess concentrations (>30 g/L) suppressed methanogenesis-related genes and led to methane production arrest despite activating specialized propionate-metabolizing bacteria such as genus Pelotomaculum schinkii. As such, an increase in the stress intensity of propionate promotes a change in the metabolic pathways of methanogens and increases methane production; however, excessive sodium propionate was not conducive to maintaining the steady state of the system. Full article

This review critically examines the multifaceted role of acetic acid bacteria (AAB) in the intricate production process of port wine vinegar, particularly in its transformative process from port wine. With the emergence of port wine vinegar as a distinctive agricultural product in 2018, producers have been faced with a diverse array of challenges, ranging from reducing the high alcohol content to preserving the inherent sweetness. Through an exhaustive exploration of acetic fermentation processes and the indispensable role of AAB, this review meticulously elucidates the complex biochemistry underlying vinegar formation, delving into the nuanced interactions between microbial activity and chemical composition. Furthermore, this review underscores the importance of sensory characteristics and consumer perception derived from vinegar production, providing invaluable insights into these fermented products’ sensory profiles and marketability. In summary, this study offers valuable insights into the evolution of port wine into vinegar, highlighting its significance in agricultural and culinary contexts. Full article

Iron deficiency anemia is a significant health problem in developing countries and this is rising, particularly in children and pregnant women. Several therapeutic properties have been attributed to Cassia grandis (carao), including the treatment against anemia, a laxative effect, and the reduction of bleeding. Yogurt is a vehicle for functional ingredients. As a result, this investigation aims to examine the application of Cassia grandis pulp as an anti-anemic and anti-dyspepsia agent in enriched yogurt. Carao pulp powder was added to milk at 0%, 0.5%, 1%, and 3% to produce yogurt. The bioavailability characteristics of iron deficiency anemia were analyzed in albino rats, which were studied for 4 weeks. Other groups of rats were used to set up the dyspepsia model by being fed a high-fat and high-calorie diet. Intestinal propulsion rate, gastric emptying rate, small intestinal contraction, motilin levels, and intestinal muscle tension were analyzed in rats with dyspepsia. Yogurt with 3% carao pulp powder restored ferritin, hemoglobin, total protein and iron at the end of the 4-week feeding period, with significant competition revealed in calcium and zinc absorbance. Furthermore, yogurt with 3% carao pulp powder improved intestinal propulsion rate, gastric emptying rate, small intestinal contraction, motilin levels, and intestinal muscle tension in dyspepsia rats. Carao can be recommended as an anti-anemia supplement in yogurt fortification. Full article

Hydroxytyrosol (HT) is a well-known compound for its bioactive properties. It is naturally present in olives, olive oil, and wine. Its presence in wines is partly due to its production during alcoholic fermentation by yeast through a hydroxylation of tyrosol formed through the Ehrlich pathway. This work aims to explore the influence of yeast assimilable nitrogen (YAN) and glucose content as precursors of HT formation during alcoholic fermentation. Commercial Saccharomyces cerevisiae QA23 and its metabolically engineered strain were used to ferment synthetic must. Each strain was tested at two different YAN concentrations (210 and 300 mg L⁻¹) and two glucose concentrations (100 and 240 g L⁻¹). This work confirms that the less YAN and the more glucose, the higher the HT content, with fermentations carried out with the metabolically engineered strain being the ones with the highest HT content (0.6 mg L⁻¹). Full article

Oxidative stress from an excess of radical compounds generally impacts apoptosis and inflammation. The use of probiotics, therefore, has emerged as a favorable tool to suppress the formation of reactive oxygen species. In the present study, we investigated the antioxidant activity of plant-derived Lactiplantibacillus (L.) plantarum MSC-5T fermented in Eriobotrya japonica (EJ) aqueous extract. In the in vitro study, the extract fermented with the MSC-5T strain markedly decreased the cell death of H₂O₂-induced HEK293 cells. In addition, the fermented extract showed a protective effect against fungal toxin ochratoxin A (OTA) and citrinin (CTN). Regarding the evaluation of glutathione homeostasis, it can be clearly seen that pretreatment of HEK293 cells with fermented EJ extract greatly increased glutathione (GSH) levels, while unfermented extract did not affect the cellular GSH content. Furthermore, we identified a bioactive compound as pyrocatechol, which displayed significant antioxidation activity. The extract fermented for 48 h with the MSC-5T strain in EJ extract produces 167.4 μg/mL pyrocatechol. Full article

In recent years, the number of conscious consumers who care about accessing safe food has increased, and this has brought about an increased interest in pickle products that do not contain preservatives and are obtained by natural fermentation. With the negative effects of food additives on health coming to the forefront, the search for new and natural methodologies in pickle production processes has begun. For this purpose, lactic acid bacteria (LAB), which is the most common bacteria in pickle fermentation and a normal microbiota member of fresh peppers, is used for natural fermentation studies in pickle production. In this context, this study aimed to sample Üçburun pepper (Capsicum annuum var. annuum L., “Golden Greek”) for LAB isolation and to compare two different pickle production techniques within the scope of industrial processing. Accordingly, sampling was performed from two different sampling points for LAB isolation. The phenotypic and biochemical characteristics of the obtained isolates were determined. Kit-based identification of 10 isolates that were determined to exhibit different profiles was carried out using the API 50CH kit. To obtain additive-free pickled peppers on an industrial scale, two different pickle production processes (fermentation and acidification methods) were applied. According to the analysis results and the differences in the production stages of stock pickles, it has been seen that the pickles obtained by the acidification method are more suitable for pickle industry production. Full article

Lignocellulosic wastes, primarily from agricultural by-products, are a renewable resource increasingly used in the sustainable production of oligosaccharides, significantly contributing to the growing bioeconomy. This innovative utilization of biological resources aligns with the global shift towards sustainable development, focusing on creating products such as food, feed, and bioenergy from renewable sources. Oligosaccharides, specialized carbohydrates, are synthesized either chemically or more eco-friendly, biologically. Biological synthesis often involves enzymes or whole-cell systems to transform lignocellulosic wastes into these valuable sugars. As functional food supplements, oligosaccharides play a crucial role in human and animal health. They serve as prebiotics, indigestible components that promote the proliferation of beneficial gut microbiota, especially within the colon. This positive impact on gut flora is essential for boosting the immune system and regulating physiological functions. Important prebiotics, including galactooligosaccharides (GOS), xylooligosaccharides (XOS), fructooligosaccharides (FOS), mannan-oligosaccharides (MOS), and isomaltooligosaccharides (IMOS), are produced through methods involving enzymes or the use of whole cells, with agricultural waste as substrates. Recent advancements focus on refining these biological processes for oligosaccharide synthesis using lignocellulosic substrates, emphasizing the principles of a circular bioeconomy, which promotes resource reuse and recycling. This review highlights the potential and challenges in the biological synthesis of oligosaccharides from renewable resources. It underscores the need for innovation in process optimization and commercialization strategies to fully exploit lignocellulosic wastes. This approach not only contributes to sustainable product development, but also opens new avenues for the profitable and environmentally friendly utilization of agricultural residues, marking a significant step forward in the bio-based industry. Full article

This study focused on the co-fermentation of food waste and tissue paper to produce ethanol, which will eliminate the need for additional nitrogen sources and nutrients, thereby reducing production costs. In response to the inhibitory effect of the high concentrations of glucose present in mixed-substrate hydrolysates on xylose fermentation, a co-fermentation process using Saccharomyces cerevisiae and Candida shehatae was proposed. This approach reduced the fermentation time by 24 h, increased the xylose utilization rate to 88%, and improved the ethanol yield from 41% to 46.5%. The impact of external conditions and corresponding optimization were also analyzed in this process. The optimum conditions were a 1:3 ratio of Saccharomyces cerevisiae to Candida shehatae, a pH of 5, and shaking at 150 r/min, and by employing dynamic temperature control, the ethanol production was increased to 21.98 g/L. Compared to conventional processes that only use Saccharomyces cerevisiae, this method enhanced the ethanol yield from 41% to 49%. Full article