In vitro simulated saliva, gastric, and intestinal digestion followed by faecal fermentation reveals a potential modulatory activity of Epimedium on human gut microbiota.

Herba Epimedii, known for its rich array of bioactive ingredients and widespread use in ethnopharmacological practices, still lacks a comprehensive understanding of its gastrointestinal biotransformation. In this study, we qualitatively explored the dynamic changes in Epimedium sagittatum components during in vitro simulated digestions, with a quantitative focus on its five major flavonoids. Notably, significant metabolism of E. sagittatum constituents occurred in the simulated small intestinal fluid and colonic fermentation stages, yielding various low molecular weight metabolites. Flavonoids like kaempferol glycosides were fully metabolized in the simulated intestinal fluid, while hyperoside digestion occurred during simulated colon digestion. Colonic fermentation led to the production of two known bioactive isoflavones, genistein, and daidzein. The content and bioaccessibility of the five major epimedium flavonoids-icariin, epimedin A, epimedin B, epimedin C, and baohuoside I-significantly increased after intestinal digestion. During colon fermentation, these components gradually decreased but remained incompletely metabolized after 72 h. Faecal samples after E. sagittatum fermentation exhibited shift towards dominance by Lactobacillus (Firmicutes), Bifidobacterium (Actinobacteria), Streptococcus (Firmicutes), and Dialister (Firmicutes). These findings enhance our comprehension of diverse stages of Herba Epimedii constituents in the gut, suggesting that the primary constituents become bioaccessible in the colon, where new bioactive compounds may emerge.

Characterization of Bacterial Cellulose Produced by Acetobacter xylinum Strain LKN6 Using Sago Liquid Waste as Nutrient Source.

<b>Background and Objective:</b> Bacterial Cellulose (BC) is an exopolysaccharide produced by bacteria with unique structural and mechanical properties and is highly pure compared to plant cellulose. This study aimed to produce novel bacterial cellulose using sago liquid waste substrate and evaluate its characteristics as a potential bioplastic.<b>Materials and Methods:</b> Production of BC by static batch fermentation was studied in sago liquid waste substrate usingAcetobacter xylinumLKN6. The BC structure was analyzed by Scanning Electron Microscopy (SEM) and Fourier Transform infrared spectroscopy (FT-IR). Mechanical properties were measured include tensile strength, elongation at break, elasticity (Young's modulus) and Water Holding Capacity (WHC). <b>Results:</b> The BC yield from sago liquid waste as a nutrients source was achieved 12.37 g L¹ and the highest BC yield 14.52 g L¹ in sago liquid waste medium with a sugar concentration of 10% (w/v) after 14 days fermentation period. The existence of bacterial cellulose is proven by FT-IR spectroscopy analysis based on the appearance of absorbance peaks, which are C-C bonding, C-O bonding, C-OH bonding and C-O-C bonding and represents the fingerprints of pure cellulose. The mechanical properties of BC from sago liquid waste were showed a tensile strength of 44.2-87.3 MPa, elongation at break of 4.8-5.8%, Young's Modulus of 0.86-1.64 GPa and water holding capacity of 85.9-98.6 g g¹. <b>Conclusion:</b> The results suggest that sago liquid waste has great potential to use as a nutrient source in the production of bacterial cellulose and BC's prospect as the bioplastic.

Evaluation of Chemical Compositions, Antioxidant Capacity and Intracellular Antioxidant Action in Fish Bone Fermented with Monascus purpureus.

Fish bones (FBs) are aquatic by-products that are sources of antioxidant-active peptides, calcium dietary supplements, and biomedical materials. Usually, fermentation of these by-products via microorganisms brings desirable changes, enhancing their value. This study investigates the value addition of FB when fermented with Monascus purpureus (MP) for different time intervals, such as 3 days (F3) and 6 days (F6). The results indicate that the soluble protein, peptide, amino acid and total phenol content, as well as the antioxidant capacity (DPPH, ABTS+ radical scavenging activity, and relative reducing power), of F3 and F6 were significantly increased after fermentation. Furthermore, the ROS contents of F3 and F6 were reduced to a greater extent than that of hydrogen peroxide (H2O2) in Clone-9 cells. The MMP integrity, as well as the SOD, CAT, and GPx activity, of F3 and F6 were also increased significantly compared to the H2O2 in Clone-9 cells. Notably, F3 and F6 displayed significant reductions in ROS content, as well as elevate, SOD activity and MMP integrity in Clone-9 cells, when compared with the native FB. These results indicate that the FBs fermented with MP for 3 days (F3), and 6 days (F6) have antioxidant capacity, with possible applications as natural food supplements.

Sulfur, fresh cassava root and urea independently enhanced gas production, ruminal characteristics and in vitro degradability.

BACKGROUND: Total fresh cassava root (FCR) production was 275 million tonnes in 2018 which equals 61.1 % of the total production, and Thailand produced 10.7 % FCR of the total production. FCR is one of the main energy source for ruminant. The limitation of FCR utilization is due to the presence of hydrogen cyanide (HCN). The study aimed to evaluate the effect of sulfur, urea and FCR at various levels on in vitro gas production, ruminal fermentation and in vitro degradability. The study hypothesized that: (1) sulfur, urea and FCR have no interaction effect and (2) effect of FCR and urea is related to sulfur addition. RESULTS: The study aimed to elucidate the optimum level of elemental sulfur, fresh cassava root (FCR) and urea and their effect on in vitro gas production, ruminal fermentation, thiocyanate concentration, and in vitro degradability. A 3 × 2 × 4 in a completely randomized design were conducted. Factor A was level of sulfur at 0 %, 1 and 2 % of concentrate dry matter (DM), factor B was level of urea at 2 and 4 % of concentrate DM, and factor C was level of the FCR at 0, 200, 300 and 400 mg DM of the total substrate. The study found that elemental sulfur, urea and FCR had no interaction effect on the kinetics of in vitro gas, ruminal fermentation, HCN and in vitro degradability. Elemental sulfur supplementation (P < 0.05) significantly increased the in vitro gas produced from an insoluble fraction (b), in vitro DM degradability and either neutral detergent fiber (NDF) or acid detergent fiber (ADF) degradability and propionate (C3) concentration while decreased the ruminal HCN concentration. Urea levels showed a (P < 0.05) significant increase of the potential extent of in vitro gas production, ruminal ammonia nitrogen (NH3-N) and total volatile fatty acid (TVFA). Fresh cassava root supplementation (P < 0.05) significantly increased the in vitro gas produced from an immediate soluble fraction (a), in vitro gas produced from insoluble fraction, in vitro gas production rate constant, total VFA, C3 concentration and HCN while decreased ruminal pH, acetate and butyrate concentration. It could be concluded that 2 % elemental sulfur, 4 % urea and 300 mg FCR showed a greater effect on in vitro gas production, ruminal fermentation and HCN reduction. CONCLUSIONS: The study found that elemental sulfur, urea, and FCR had no interaction effect on the kinetics of in vitro gas, total in vitro gas, ruminal fermentation, and HCN concentration. It could be concluded that 2 % elemental sulfur, 4 % urea, and 300 mg FCR showed a greater effect on in vitro gas production, ruminal fermentation, and HCN reduction.

The Protection of Lactic Acid Bacteria Fermented-Mango Peel against Neuronal Damage Induced by Amyloid-Beta.

Mango peels are usually discarded as waste; however, they contain phytochemicals and could provide functional properties to food and promote human health. This study aimed to determine the optimal lactic acid bacteria for fermentation of mango peel and evaluate the effect of mango peel on neuronal protection in Neuron-2A cells against amyloid beta (Aß) treatment (50 µM). Mango peel can be fermented by different lactic acid bacteria species. Lactobacillus acidophilus (BCRC14079)-fermented mango peel produced the highest concentration of lactic acid bacteria (exceeding 108 CFU/mL). Mango peel and fermented mango peel extracts upregulated brain-derived neurotrophic factor (BDNF) expression for 1.74-fold in Neuron-2A cells. Furthermore, mango peel fermented products attenuated oxidative stress in Aß-treated neural cells by 27%. Extracts of L. acidophilus (BCRC14079)-fermented mango peel treatment decreased Aß accumulation and attenuated the increase of subG1 caused by Aß induction in Neuron-2A cells. In conclusion, L. acidophilus (BCRC14079)-fermented mango peel acts as a novel neuronal protective product by inhibiting oxidative stress and increasing BDNF expression in neural cells.

Metabolome analysis revealed that soybean-Aspergillus oryzae interaction induced dynamic metabolic and daidzein prenylation changes.

Several isoflavonoids are well known for their ability to act as soybean phytoalexins. However, the overall effects of the soybean-Aspergillus oryzae interaction on metabolism remain largely unknown. The aim of this study is to reveal an overview of nutritive and metabolic changes in germinated and A. oryzae-elicited soybeans. The levels of individual nutrients were measured using the ustulation, ashing, Kjeldahl, and Folch methods. The levels of individual amino acids were measured using high-performance liquid chromatography. Low-molecular-weight compounds were measured through metabolome analysis using liquid chromatography-mass spectrometry. Although the levels of individual nutrients and amino acids were strongly influenced by the germination process, the elicitation process had little effect on the change in the contents of individual nutrients and amino acids. However, after analyzing approximately 700 metabolites using metabolome analysis, we found that the levels of many of the metabolites were strongly influenced by soybean-A. oryzae interactions. In particular, the data indicate that steroid, terpenoid, phenylpropanoid, flavonoid, and fatty acid metabolism were influenced by the elicitation process. Furthermore, we demonstrated that not the germination process but the elicitation process induced daidzein prenylation, suggesting that the soybean-A. oryzae interactions produce various phytoalexins that are valuable for health promotion and/or disease prevention.

Fecal microbial transplantation and fiber supplementation in patients with severe obesity and metabolic syndrome: a randomized double-blind, placebo-controlled phase 2 trial.

Fecal microbial transplantation (FMT) from lean donors to patients with obesity has been associated with metabolic benefits, yet results so far have been inconsistent. In this study, we tested the application of daily fiber supplementation as an adjunct to FMT therapy to modulate cardiometabolic outcomes. We performed a double-blind randomized trial in patients with severe obesity and metabolic syndrome receiving oral FMT, to test high-fermentable (HF) and low-fermentable (LF) fiber supplements (NCT03477916). Seventy participants were randomized to the FMT-HF (n = 17), FMT-LF (n = 17), HF (n = 17) and LF (n = 19) groups. The primary outcome was the assessment of change in insulin sensitivity from baseline to 6 weeks using the homeostatic model assessment (HOMA2-IR/IS). After 6 weeks, only patients in the FMT-LF group had significant improvements in HOMA2-IR (3.16 ± 3.01 at 6 weeks versus 3.77 ± 3.57 at baseline; P = 0.02). No difference in HOMA2-IR was observed over this period for those in the FMT-HF group (3.25 ± 1.70 at 6 weeks versus 3.17 ± 1.72 at baseline; P = 0.8), the HF group (3.49 ± 1.43 at 6 weeks versus 3.26 ± 1.33 at baseline; P = 0.8) or the LF group (3.76 ± 2.01 at 6 weeks versus 3.56 ± 1.81 at baseline; P = 0.8). Interventions were safe and well-tolerated with no treatment-attributed serious adverse events. We provide proof of concept for the use of a single-dose oral FMT combined with daily low-fermentable fiber supplementation to improve insulin sensitivity in patients with severe obesity and metabolic syndrome.

Influencing Factors on the Physicochemical Characteristics of Tea Polysaccharides.

Tea polysaccharides (TPSs) are one of the main bioactive constituents of tea with various biological activities such as hypoglycemic effect, antioxidant, antitumor, and immunomodulatory. The bioactivities of TPSs are directly associated with their structures such as chemical composition, molecular weight, glycosidic linkages, and conformation among others. To study the relationship between the structures of TPSs and their bioactivities, it is essential to elucidate the structure of TPSs, particularly the fine structures. Due to the vast variation nature of monosaccharide units and their connections, the structure of TPSs is extremely complex, which is also affected by several major factors including tea species, processing technologies of tea and isolation methods of TPSs. As a result of the complexity, there are few studies on their fine structures and chain conformation. In the present review, we aim to provide a detailed summary of the multiple factors influencing the characteristics of TPS chemical structures such as variations of tea species, degree of fermentation, and preparation methods among others as well as their applications. The main aspects of understanding the structural difference of TPSs and influencing factors are to assist the study of the structure and bioactivity relationship and ultimately, to control the production of the targeted TPSs with the most desired biological activity.

Pectin and homogalacturonan with small molecular mass modulate microbial community and generate high SCFAs via in vitro gut fermentation.

The intestinal fermentability of pectic polysaccharides is largely determined by its molecular size. In this study, fermentation properties of enzymatic-modified apple pectin (AP) and homogalacturonans (HG) with high, medium and low molecular weight (Mw) were evaluated by in vitro fermentation model, and their structural changes were also investigated. Results showed that Mw, monosaccharide contents and molecular linearity of the AP hydrolysates were reduced after microbial degradation. On the other hand, culture media supplemented with low-Mw AP (60,300 g/mol) and low-Mw HG (861 g/mol) exhibited lower pH (5.1 and 5.7, respectively) and produced higher total short-chain fatty acid contents (SCFA, 230.40 mmol/L and 187.19 mmol/L, respectively). However, reduced trends in abundance of the pectinolytic microorganisms Faecalibacterium and Eubacterium were showed as Mw of the HG decreased, whereas growth of the SCFA-producer genera Bifidobaacterium, Megasphaera and Allisonella were improved. This work confirmed that low-Mw pectin and homogalacturonan generated more beneficial metabolites, developing structure-microbiota-gut health relationship.

Bioconversion of potato solid waste into antifungals and biopigments using Streptomyces spp.

Potato waste was processed and used as a sole substrate for simultaneously producing antifungals and biopigments using Streptomyces spp. Out of three different Streptomyces isolates, strain SO6 stood out due to its ability to produce antifungals against economically important fungal phytopathogens and intracellular biopigments using potato waste powders without additional nutrients. This strain also showed the potential to secrete a broad range of enzymes for fermentation of eight sugars that could be involved in potato waste bioconversion. The results of the fermentation assay indicated that Streptomyces sp. strain SO6 degrades potato wastes during submerged fermentation, diminishing total dry weight and increasing reducing sugars from 0.3 to 3.6 mg·mL-1 and total proteins from 70.6 to 187.7 µg·mL-1. The results showed that Streptomyces strain SO6 was able to convert the potato waste into 0.96 mg·g-1 of diffusible antifungals and 1.75 mg·g-1 of reddish-purple biopigments. On the contrary, an absence of pigment production was observed during the fermentation of the commercial medium used as reference. According to our results, replacement of commercial culture media with available low-cost agroindustrial wastes for producing bioactive chemicals is a real opportunity to enhance the Streptomyces pigment production and antibiotic sustainability with cost-competitiveness. To our knowledge, this is the first report on the simultaneous production of biopigments and diffusible antifungal antibiotics produced by Streptomyces spp. using potato solid waste as the sole nutrient source.

Prebiotic peptides, their formation, fermentation in the gut, and health implications.

Prebiotics can be synthesized from sources other than dietary fibers, such as proteins. The proteins, when processed into peptides have healthful or deleterious effects on the host. Outside living systems, prebiotic peptides (PP) are formed via preformation of amino acids or related monomeric building blocks, resulting in nonenzymatic polymerization/ligation to produce peptides. Whereas, inside living systems like the human gut, many metabolic pathways are involved in PP production, and mostly involve host-microbiota interactions. The interplay is responsible for PP activities and their implications on host amino acid balance and metabolism. Similar to carbohydrates fermentation, PP will yield short chain fatty acids (SCFA), but also branched chain fatty acids (BCFAs), phenols, indole, hydrogen sulfide, amines, and ammonia, capable of biologically mediating molecular signals. This holistic review considers a brief description of prebiotics, and tracks down prebiotic peptides formation processes, interactions with gut microbes, and health outcomes.

Effect of feeding Bacillus subtilis on rumen fermentation, blood metabolites, nutrient digestibility, and energy and nitrogen balances in non-lactating crossbred cows.

The purpose of this study was to investigate the effects of feeding Bacillus subtilis on rumen fermentation, blood metabolites, nutrient digestibility, and energy and nitrogen balances in non-lactating crossbred (Holstein-Friesian × Bos indicus) cows. Four cows were assigned to the control and B. subtilis diets in a crossover design, and respiratory and metabolic experiments were conducted. For the B. subtilis diet, B. subtilis DSM15544 spores were added at the rate of 1.0 × 1010  CFU/head/day to the control diet. At 4 hr after feeding, cows fed the B. subtilis diet had increased levels of i-butyric acid in the rumen fluid and tended to have lower concentrations of plasma non-esterified fatty acids when compared with cows fed the control diet. This suggests that feeding B. subtilis could improve energy efficiency. However, there was no effect on energy retention in this study. Although there were no effects on nutrient digestibility, nitrogen balance, or methane production, heat production was significantly higher in cows fed the B. subtilis diet than in those fed the control diet.

Impact of early-life feeding on local intestinal microbiota and digestive system development in piglets.

Early-life gut microbial colonisation is known to influence host physiology and development, shaping its phenotype. The developing gastro-intestinal tract of neonatal piglets provides a "window of opportunity" for programming their intestinal microbiota composition and corresponding intestinal development. Here, we investigated the impact of early feeding on jejunum and colon microbiota composition, and intestinal maturation in suckling piglets. From two days of age, early-fed (EF; n = 6 litters) piglets had access to solid feed containing a mixture of fibres till weaning (day29) in addition to sow's milk, whereas the control (CON; n = 6 litters) piglets exclusively fed on sow's milk. Early feeding elicited a significant impact on the colon microbiota, whereas no such effect was seen in the jejunal and ileal microbiota. Quantified eating behavioural scores could significantly explain the variation in microbiota composition of EF piglets and support their classification into good, moderate, and bad eaters. Members of the Lachnospiraceae family, and the genera Eubacterium, Prevotella, and Ruminococcus were quantitatively associated with eating scores. EF piglets were found to have a decreased pH in caecum and colon, which coincided with increased short-chain fatty acid (SCFA) concentrations. Moreover, they also had increased weights and lengths of several intestinal tract segments, as well as a decreased villus-crypt ratio in jejunal mucosa and an increased abundance of proliferative cells in colon mucosa. The approaches in this study indicate that early feeding of a mixed-fibre (pre-weaning) diet changes the microbiota composition, pH, and fermentation products in the distal gut of piglets, while it also alters both macroscopic and microscopic intestinal measurements. These results exemplify the potential of early feeding to modulate intestinal development in young piglets.

Fate of antibiotic resistance genes and metal resistance genes during the thermophilic fermentation of solid and liquid swine manures in an ectopic fermentation system.

Environmental pollution due to resistance genes from livestock manure has become a serious issue that needs to be resolved. However, little studies focused on the removal of resistance genes in simultaneous processing of livestock feces and urine. This study investigated the fate of antibiotic resistance genes (ARGs), metal resistance genes (MRGs), and class 1 integron-integrase gene (intI1) during thermophilic fermentation of swine manure in an ectopic fermentation system (EFS), which has been regarded as a novel system for efficiently treating both feces and urine. The abundances of MRGs and tetracycline resistance genes were 34.44-97.71% lower in the EFS. The supplementation of heavy metals significantly increased the abundance of intI1, with the enhancement effect of copper being more prominent than that of zinc. The highest abundances of resistance genes and intI1 were observed at high Cu levels (A2), indicating that Cu can increase the spreading of resistance genes through integrons. Network analysis revealed the co-occurrence of ARGs, MRGs, and intI1, and these genes potentially shared the same host bacteria. Redundancy analysis showed that the bacterial community explained most of the variations in ARGs, and environmental factors had influences on ARGs abundances by modulating the bacterial community composition. The decreased Sphingomonas, Comamonas, Acinetobacter, Lactobacillus, Bartonella, Rhizobium, and Bacteroides were mainly responsible for the reduced resistance genes. These results demonstrate that EFS can reduce resistance genes in simultaneous processing of livestock feces and urine.

Structural characterization, functional and biological activities of an exopolysaccharide produced by probiotic Bacillus licheniformis AG-06 from Indian polyherbal fermented traditional medicine.

An exopolysaccharide (EPS) was purified from the probiotic bacterium Bacillus licheniformis AG-06 isolated from the polyherbal fermented traditional medicine (Ashwagandharishta) of Indian Ayurveda. High-performance liquid chromatography (HPLC) based compositional analysis exhibits the heteropolymeric nature of the EPS consisting of galactose, rhamnose, xylose, mannose, and glucose, as the monomeric units. Fourier-transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopic analyses confirm the presence of typical carbohydrate polymer functional groups and structural units, respectively. The purified EPS demonstrates the web-like fibrous and porous nature in scanning electron microscopic and atomic force microscopic studies. The purified EPS had shown 71.83% and 67.79% of flocculation and emulsification activities, respectively. Antioxidant activity was evaluated against 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), nitric oxide, and superoxide free radicals and the scavenging actions were increased in a dose-dependent manner. Moreover, the purified EPS exhibits a significant cytotoxic activity against the human lung carcinoma cells (A549), which strongly suggests the anticancer potential of the EPS derived from B. licheniformis AG-06.

In vitro simulated digestion and colonic fermentation of lychee pulp phenolics and their impact on metabolic pathways based on fecal metabolomics of mice.

Lychee pulp phenolics (LPP) was subjected to four simulated gastrointestinal digestions and colonic fermentation to investigate the changes in its phenolic composition and bioactivities; the fecal metabolic profiles of LPP-fed mice were also elucidated using UHPLC-ESI-QTOF-MS/MS. After simulated salivary, gastric and intestinal digestion, slight increases in phenolic acids and (+)-catechin occurred relative to undigested LPP, whereas other flavonoids showed an opposite trend. Unlike the above-described separate simulated digestions, successive gastrointestinal digestion significantly enhanced the release of phenolic compounds (p < 0.05), gallic acid (413.79%), ferulic acid (393.69%), (+)-catechin (570.27%) and rutin (247.54%). During colonic fermentation, ten detected phenolics were utilized by gut microbes, among which procyanidin B2 (22.35%) was the most degraded. LPP fermentation accelerated the production of short-chain fatty acids (122.79%). The metabolic pathways altered by LPP including unsaturated fatty acid, biotin, and nicotinamide metabolism may be the potential regulatory mechanisms and associated with the integrity of the gut barrier. These findings indicate that LPP may act as a promising candidate to protect gut health.

Protective role of fermented mulberry leave extract in LPS­induced inflammation and autophagy of RAW264.7 macrophage cells.

Mulberry leaves have antioxidant activity and anti­inflammatory effects in several types of cells. However, the efficacy of mulberry leaves fermented with Cordyceps militaris remains unknown. Therefore, the present study aimed to investigate whether the ethanol extracts of mulberry leaves fermented with C. militaris (EMfC) can prevent lipopolysaccharide (LPS)­induced inflammation and autophagy in macrophages. To achieve this, RAW264.7 cells pretreated with three different dose of EMfCs were subsequently stimulated with LPS, and examined for alterations in the regulatory factors of inflammatory responses and key parameters of the autophagy signaling pathway. EMfC treatment inhibited the generation of reactive oxidative species; however, significant activity was observed for 2,2­diphenyl­1­picrylhydrazyl (DPPH) radical scavenging (IC50=579.6703 mg/ml). Most regulatory factors in inflammatory responses were significantly inhibited following treatment with EMfC, without any significant cellular toxicity. EMfC­treated groups exhibited marked suppression of nitrogen oxide (NO) levels, mRNA expression levels of iNOS/COX­2, levels of all inflammatory cytokines (TNF­α, IL­1ß and IL­6) and phosphorylation of MAPK members, as well as recovery of cell cycle progression. Furthermore, similar effects were observed in the LPS­induced autophagy signaling pathway of RAW264.7 cells. The expression levels of microtubule­associated protein 1A/1B­light chain 3 (LC3) and Beclin exhibited a dose­dependent decrease in the EMfC+LPS­treated groups compared with in the Vehicle+LPS­treated group, whereas the phosphorylation of PI3K and mTOR were enhanced in a dose­dependent manner in the same groups. Overall, the results of the present study provide evidence that exposure to EMfC protects against LPS­induced inflammation and autophagy in RAW264.7 cells. These results indicated that EMfC is a potential candidate for treatment of inflammatory diseases.

Fermentative production of Vitamin E tocotrienols in Saccharomyces cerevisiae under cold-shock-triggered temperature control.

The diverse physiological functions of tocotrienols have listed them as valuable supplementations to α-tocopherol-dominated Vitamin E products. To make tocotrienols more readily available, tocotrienols-producing S. cerevisiae has been constructed by combining the heterologous genes from photosynthetic organisms with the endogenous shikimate pathway and mevalonate pathway. After identification and elimination of metabolic bottlenecks and enhancement of precursors supply, the engineered yeast can produce tocotrienols at yield of up to 7.6 mg/g dry cell weight (DCW). In particular, proper truncation of the N-terminal transit peptide from the plant-sourced enzymes is crucial. To further solve the conflict between cell growth and tocotrienols accumulation so as to enable high-density fermentation, a cold-shock-triggered temperature control system is designed for efficient control of two-stage fermentation, leading to production of 320 mg/L tocotrienols. The success in high-density fermentation of tocotrienols by engineered yeast sheds light on the potential of fermentative production of vitamin E tocochromanols.

Understanding the interaction of isoleucine paired with other amino acids in soy whey alcohol fermentation using Torulaspora delbrueckii.

Soy (tofu) whey is a liquid by-product generated from tofu (soybean curd) production and it is often discarded off as a waste liquid by the tofu manufacturers. Previous studies have demonstrated that soy whey can be biotransformed into a soy alcoholic beverage by using Saccharomyces and non-Saccharomyces yeasts even though soy whey is low in yeast assimilable nitrogen (YAN) content. In this study, the initial YAN of the soy whey was estimated to be 46.6 mg N/L and Torulaspora delbrueckii Biodiva was used to ferment soy whey supplemented with either isoleucine only or isoleucine paired with valine, leucine or phenylalanine (each amino acid supplemented at a dosage of 30 mg N/L). Amino acid supplementation was found to enhance sugar utilization by the yeast, which led to higher ethanol production (7.49% v/v in control versus 8.35-8.80% v/v in supplemented samples). Samples supplemented with isoleucine only experienced slower sugar utilization during the fermentation as compared to the paired amino acid samples, but the yeast was still able to utilize the sugar to low levels at the end of the fermentation. The presence of leucine supplementation counteracted the "inhibition" induced by the presence of isoleucine at the first day of the fermentation. Amino acid supplementation slowed down glutamic acid utilization and resulted in higher levels of residual glutamic acid and alanine. Amino acid supplementation increased the corresponding fusel alcohol production and the presence of other amino acids reduced the active amyl alcohol production. Therefore, interactions between amino acids can impact the metabolism of the yeast as well as the flavor modulation during soy whey fermentation.

The crucial role of yeasts in the wet fermentation of coffee beans and quality.

The objective of this study was to investigate the role of yeasts in the wet fermentation of coffee beans and their contribution to coffee quality using a novel approach. Natamycin (300 ppm) was added to the fermentation mass to suppress yeast growth and their metabolic activities, and the resultant microbial ecology, bean chemistry and sensory quality were analyzed and compared to non-treated spontaneous fermentation we reported previously. The yeast community was dominated by Hanseniaspora uvarum and Pichia kudriavzevii and grew to a maximum population of about 5.5 log CFU/g in the absence of Natamycin, while when Natamycin was added yeasts were suppressed. The major bacterial species in both the spontaneous and yeast-suppressed fermentations included the lactic acid bacteria Leuconostoc mesenteroides and Lactococcus lactis, the acetic acid bacteria Gluconobacter cerinus and Acetobacter persici and the Enterobacteriaceae Enterobacter, Citrobacter and Erwinia. For both fermentations, the mucilage layers were completely degraded by the end of the process and the absence of yeast activities had no significant impact on mucilage degradation. During fermentation, reducing sugars were consumed while lactic acid was accumulated inside the beans, and its concentration was significantly higher in the spontaneous fermentation (3 times) than that where yeasts were suppressed by Natamycin. Glycerol was detected with a concentration of 0.08% in the absence of Natamycin and was not identified when Natamycin was added. Green beans fermented with yeast growth contained a higher amount of isoamyl alcohol (21 times), ethanol (3.7 times), acetaldehyde (8 times), and ethyl acetate (25 times) compared to beans fermented in the absence of yeast activities, which remained higher in the former after roasting. Beans fermented without yeast activities had a mild fruity aroma, and lower sensory scores of fragrances (7.0), flavor (6.5), acidity (6.3), body (7.0) and overall score (6.5) compared to the former. These findings demonstrated the crucial roles of yeasts in wet fermentation of coffee beans and for producing high quality coffee.