Search Results (110)

Sichuan Paocai is a representative traditional fermented vegetable in China, which is deeply embedded in local geographical and cultural heritage. However, regional differences in product characteristics remain poorly understood. In this study, the physicochemical properties, volatile compounds, and microbial communities of Paocai from seven production regions in Sichuan (named FB, AB, BZ, CD, DZ, MY, and YS) were systematically investigated. Parameters including pH, salinity, nitrite, organic acids, and color were determined, while volatile profiles were analyzed using an electronic nose and comprehensive two-dimensional gas chromatography–mass spectrometry. A total of 294 volatile compounds were identified, with alcohols, esters, and isothiocyanates emerging as the major contributors to flavor differentiation. UMAP and OPLS-DA analyses revealed distinct regional clustering, which was consistent with electronic nose profiling, and 111 volatile compounds were identified as key aroma markers. Microbial diversity was assessed using 16S rRNA gene sequencing, demonstrating that Lactobacillus, Lentilactobacillus, Pediococcus, and Weissella were the dominant taxa, although the richness varied significantly across regions. An LEfSe analysis further identified region-specific biomarkers, including Pediococcus, Lactococcus, and Leuconostoc in FB; Lactobacillus in AB; Pediococcus ethanolidurans in BZ; Levilactobacillus in DZ; Lentilactobacillus in MY; and a more diverse microbiota in MS. A correlation analysis highlighted the pivotal roles of distinct microbial groups in shaping and transforming flavor compounds across different regions. Overall, these findings provide scientific guidance for the development of high-quality, region-specific products and contribute to the protection, branding, and market competitiveness of geographically indicated foods. Full article

The industrial potential of Clostridium beijerinckii for acetone–butanol–ethanol (ABE) fermentation is limited by oxygen sensitivity and suboptimal solvent productivity. Peroxide repressor (PerR), a key negative regulator protein, is reported to suppress the oxidative stress defense system in anaerobic clostridia, leading to poor survival of bacteria under aerobic conditions. However, the regulatory mechanism underlying this phenomenon remains unclear. This study demonstrates that targeted deletion of perR (Cbei_1336) in the solvent-deficient strain C. beijerinckii DS confers robust oxygen tolerance and enhances ABE fermentation performance. The engineered perR mutant exhibited unprecedented aerobic growth under atmospheric oxygen (21% O₂), achieving a (3.79 ± 0.09)-fold increase in biomass accumulation, a (2.84 ± 0.12)-fold improvement in glucose utilization efficiency, a (57.23 ± 0.01)-fold elevation in butanol production, and a (32.78 ± 0.02)-fold amplification in acetone output compared to the parental strain. Transcriptomic analysis revealed that perR knockout simultaneously upregulated oxidative defense systems and activated ABE pathway-related genes. This genetic rewiring redirected carbon flux from acidogenesis to solventogenesis, yielding a (9.64 ± 0.90)-fold increase in total solvent titer (15.61 ± 0.89 vs. 1.62 ± 0.12 g/L) and a (2.71 ± 0.04)-fold rise in volumetric productivity (0.19 ± 0.01 vs. 0.07 ± 0.01 g/L/h). Our findings establish PerR as a master regulator of both oxygen resilience and metabolic reprogramming, providing a scalable engineering strategy for industrial oxygen-tolerant ABE bioprocessing toward low-cost biobutanol production. Full article

Valorisation of spent yeast biomass post-fermentation requires energy-intensive autolysis or enzymatic hydrolysis that reduces the net benefit. Here, we present a simple and reproducible method for generating functional yeast extract recycled from Komagataella phaffii biomass without a requirement of a pre-treatment process. Spent yeast pellets from fermentations were freeze-dried to produce a fine powder that can be used directly at low concentrations, 0.0015% (w/v), together with 2% peptone (w/v), to formulate complete media ready for secondary fermentations. This media formulation supported growth rates of yeast culture that were statistically indistinguishable (p-value > 0.05) from cultures grown in standard YPD media containing commercial yeast extract, and these cultures produced equivalent titres of recombinant β-glucosidase (0.998 Abs_405nm commercial extract vs. 0.899 Abs_405nm recycled extract). Additionally, nutrient analyses highlight equivalent levels of sugars (~23 g/L), total proteins, and cell yield per carbon source (~2.17 g) with this recycled yeast extract media formulation when compared to commercial media. This method reduces process complexity and cost and enables the circular reuse of yeast biomass. The protocol is technically straightforward to implement, using freeze drying that is commonly available in research laboratories, representing a broadly applicable and sustainable alternative to conventional media supplementation that achieves a circular approach within the same fermentation system. Full article

Developing efficient, clean, and sustainable lignocellulose pretreatment technologies is essential for second-generation biofuel production. In this study, we attempted to use downstream-separated binary acetone-water, n-butanol-water, and ethanol-water solutions as the initial liquor for upstream organosolv pulping, in order to achieve the efficient and economic closed-circuit clean fractionation of the lignocelluloses for biological acetone–butanol–ethanol (ABE) production. Parameters, including concentration and temperature of the organosolv pulping, were optimized systematically. Results indicated that the 50 wt% ethanol and 30 wt% acetone aqueous solutions and pulping at 200 °C for 1 h exhibited better corn stover fractionation performances with higher fermentable sugar production. The total monosaccharide recovery (including glucose and xylose) was 50.92% and 50.89%, respectively, in subsequent enzymatic saccharification. While pulping corn stover using n-butanol solution as initial liquor showed higher delignification 86.16% (50 wt% of n-butanol and 200 °C for 1 h), the hydrolysate obtained by the organosolv pulps always exhibited good fermentability. A maximized 15.0 g/L of ABE with 0.36 g/g of yield was obtained in Ethanol-200 °C-50% group, corresponding to 112 g of ABE production from 1 kg of raw corn stover. As expected, the lignin specimens fractionated by closed-circuit organosolv pulping exhibited narrow molecule weight distribution, high purity, and high preservation of active groups, which supports further valorization. This novel strategy tightly bridges the upstream and downstream processes of second-generation ABE production, providing a new route for ‘energy-matter intensive’ and environmentally friendly lignocelluloses biorefineries. Full article

Developing a more efficient, cleaner, and energy-saving pretreatment process is the primary goal for lignocellulosic biofuels production. This study demonstrated the feasibility of circulating high-concentration acetone–butanol–ethanol (ABE) obtained via in situ product recovery (ISPR) as a pretreatment liquor. Taking ABE solvent separated from pervaporation (PV) and gas stripping (GS) as examples, results indicated that under dilute alkaline (1% NaOH) catalysis, the highly recalcitrant lignocellulosic matrices can be efficiently depolymerized, thereby improving fermentable sugars recovery in saccharification stage and ABE yield in subsequent fermentation stage. Results also revealed delignification of 91.5% (stream from PV) and 94.3% (stream from GS), with total monosaccharides recovery rates of 56.5% and 57.1%, respectively, can be realized when using corn stover as feedstock. Coupled with ABE fermentation, mass balance indicated a maximal 106.6 g of ABE (65.8 g butanol) can be produced from 1 kg of dry corn stover by circulating the GS condensate in pretreatment (the optimized pretreatment conditions were 1% w/v alkali and 160 °C for 1 h). Additionally, technical lignin with low molecular weight and narrow distribution was isolated, which enabled further side-stream valorisation. Therefore, integrating ISPR product circulation with lignocellulosic biobutanol shows strong potential for application under the concept of biorefinery. Full article

Biobutanol is becoming more relevant as a promising alternative biofuel, primarily due to its advantageous characteristics. These include a higher energy content and density compared to traditional biofuels, as well as its ability to mix effectively with gasoline, further enhancing its viability as a potential replacement. A viable strategy for attaining carbon neutrality, reducing reliance on fossil fuels, and utilizing sustainable and renewable resources is the use of biomass to produce biobutanol. Lignocellulosic materials have gained widespread recognition as highly suitable feedstocks for the synthesis of butanol, together with various value-added byproducts. The successful generation of biobutanol hinges on three crucial factors: effective feedstock pretreatment, the choice of fermentation techniques, and the subsequent enhancement of the produced butanol. While biobutanol holds promise as an alternative biofuel, it is important to acknowledge certain drawbacks associated with its production and utilization. One significant limitation is the relatively high cost of production compared to other biofuels; additionally, the current reliance on lignocellulosic feedstocks necessitates significant advancements in pretreatment and bioconversion technologies to enhance overall process efficiency. Furthermore, the limited availability of biobutanol-compatible infrastructure, such as distribution and storage systems, poses a barrier to its widespread adoption. Addressing these drawbacks is crucial for maximizing the potential benefits of biobutanol as a sustainable fuel source. This document presents an extensive review encompassing the historical development of biobutanol production and explores emerging trends in the field. Full article

Aeromonas spp. are opportunistic pathogens that are widely distributed in water sources, with several species being associated with fish and human diseases. We have previously identified an Aeromonas AB005 isolate from diseased Acipencer baerii. This isolate was identified as A. hydrophila based on the 16S rRNA and gyrB gene sequences. However, this novel strain does not produce indole and tested negative for ornithine decarboxylase and d-xylose fermentation—differences that set it apart from typical A. hydrophila strains. In the present study, this strain was subjected to whole-genome sequencing and compared with the genomes of the type strain (Aeromonas hydrophila ATCC 7966^T) and other Aeromonas spp. Comprehensive genome analysis suggests that AB005 represents a distinct species within the genus. The draft genome of the AB005 strain comprises 4,780,815 base pairs with a GC content of 61.2% and contains 6104 predicted protein-coding sequences along with numerous genes implicated in antibiotic resistance. The core/pan-genome analysis reveals extensive genetic diversity, indicative of a dynamic genomic structure. These findings collectively underscore the taxonomic distinction of the AB005 strain as a novel species and highlight its potential pathogenic implications in aquaculture and public health settings. Full article

The discovery that human beings may endogenously produce ethanol is not new and dates back at the end of the 19th century; recently, however, it has become clear that through the proliferation of gut microorganisms that produce ethanol from sugars or other substrates, blood alcohol level may be greater than 0, despite Homo sapiens sapiens lacking the enzymatic pathways to produce it. Very rarely this can lead to symptoms and/or to a disease, named gut fermentation syndrome or auto-brewery syndrome (ABS). The list of microorganisms (mostly bacteria and fungi) is very long and contains almost 100 different strains, and many metabolic pathways are involved. Endogenous ethanol production is a neglected entity, but it may be suspected in patients in whom ethanol consumption may be firmly excluded. Nevertheless, due to the growing prevalence of NAFLD (now renamed as MAFLD) worldwide, an ethanol-producing microorganism responsible for endogenous ethanol production such as Klebsiella pneumoniae or Saccharomices cerevisiae is increasingly sought in NAFLD patients, or in patients with metabolic diseases such as diabetes mellitus, obesity, or metabolic syndrome, at least in selected instances. In the absence of standard diagnostic and therapeutic guidelines, ABS requires a detailed patient history, including dietary habits, alcohol consumption, and gastrointestinal symptoms, and a comprehensive physical examination to detect unexplained ethanol intoxication. It has been proposed to start the diagnostic protocol with a standardized carbohydrate challenge test, followed, if positive, by the use of antifungal agents or antibiotics; indeed, fecal microbiota transplantation might be the only way to cure a patient with refractory ABS. Scientific societies should produce internationally agreed recommendations for ABS and other conditions linked to excessive endogenous ethanol production. Full article

The objective of this study was to assess the effects of gallic acid (GA) on nutrient degradability, gas production, rumen fermentation, and the microbial community and its functions using in vitro fermentation methods. An in vitro experiment was conducted to test GA dose levels (0, 5, 10, 20, and 40 mg/g DM) in the cow’s diet. Based on the results of nutrient degradability, gas production, and rumen fermentation, the control group (0 mg/g DM, CON) and the GA group (10 mg/g DM, GA) were selected for metagenomic analysis to further explore the microbial community and its functions. The degradability of dry matter and crude protein, as well as total gas production, CH₄ production, CH₄/total gas, CO₂ production, and CO₂/total gas, decreased quadratically (p < 0.05) with increasing GA doses, reaching their lowest levels at the 10 mg/g DM dose. Total volatile fatty acid (VFA) (p = 0.004), acetate (p = 0.03), and valerate (p = 0.03) exhibited quadratic decreases, while butyrate (p = 0.0006) showed a quadratic increase with increasing GA doses. The 10 mg/g DM dose group had the lowest levels of total VFA, acetate, and valerate, and the highest butyrate level compared to the other groups. The propionate (p = 0.03) and acetate-to-propionate ratio (p = 0.03) linearly decreased with increasing gallic acid inclusion. At the bacterial species level, GA supplementation significantly affected (p < 0.05) a total of 38 bacterial species. Among these, 29 species, such as Prevotellasp.E15-22, bacteriumP3, and Alistipessp.CAG:435, were less abundant in the GA group, while 9 species, including Aristaeella_lactis and Aristaeella_hokkaidonensis, were significantly more abundant in the GA group. At the archaeal species level, the relative abundances of Methanobrevibacter_thaueri, Methanobrevibacter_boviskoreani, and Methanobrevibactersp.AbM4 were significantly reduced (p < 0.05) by GA supplementation. Amino sugar and nucleotide sugar metabolism, Starch and sucrose metabolism, Glycolysis/Gluconeogenesis, and Pyruvate metabolismwere significantly enriched in the GA group (p < 0.05). Additionally, Alanine, aspartate and glutamate metabolism was also significantly enriched in the GA group (p < 0.05). GA use could potentially be an effective strategy for methane mitigation; however, further research is needed to assess its in vivo effects in dairy cows over a longer period. Full article

In recent years, one of the most important issues in public health is the rapid growth of antibiotic resistance among pathogens. Multidrug-resistant (MDR) strains (mainly Enterobacteriaceae and non-fermenting bacilli) cause severe infections, against which commonly used pharmaceuticals are ineffective. Therefore, there is an urgent need for new treatment options and drugs with innovative mechanisms of action. Natural compounds, especially alkaloids, are showing promising potential in this area. This review focuses on the ability of the isoquinoline alkaloid berberine (BRB) to overcome various resistance mechanisms against conventional antimicrobial agents. BRB has demonstrated significant activity in inhibiting efflux pumps of the RND (Resistance-Nodulation-Cell Division) family, such as MexAB-OprM (P. aeruginosa) and AdeABC (A. baumannii). Moreover, BRB was able to decrease quorum sensing activity in both Gram-positive and Gram-negative pathogens, resulting in reduced biofilm formation and lower bacterial virulence. Additionally, BRB has been identified as a potential inhibitor of FtsZ, a key protein responsible for bacterial cell division. Particularly noteworthy, though requiring further investigation, are reports suggesting that BRB might inhibit β-lactamase enzymes, including NDM, AmpC, and ESβL types. The pleiotropic antibacterial actions of BRB, distinct from the mechanisms of traditional antibiotics, offer hope for breaking bacterial resistance. However, more extensive studies, especially in vivo, are necessary to fully evaluate the clinical potential of BRB and determine its practical applicability in combating antibiotic-resistant infections. Full article

The wastage of by-products generated in the food industry is an issue that should be addressed by determining a second use for these products, with sourdough fermentation being the most popular technology used. The aim of this research was to evaluate the impact of adding agave bagasse (AB) and Lactococcus lactis NRRL B-50307 to sourdough that was later used in the formulation of bread rolls. Five treatments were tested: B1: wheat flour; BI2: wheat flour inoculated with L. lactis (1 × 10⁶ CFU/mL); C10: wheat flour + AB (10% w/w); T5: 5% AB + wheat flour inoculated with L. lactis (1 × 10⁶ CFU/mL); and T10: 10% AB + wheat flour inoculated with L. lactis (1 × 10⁶ CFU/mL). Sourdoughs were back-slopped daily for 6 days, dried in a climatic chamber, reactivated, and left to ferment for 24 h. Samples of each treatment of dried and reactivated sourdough were collected and tests for antioxidant activity (DPPH and ABTS), total amino acid content (OPA), and phenolic and flavonoid content were performed. Phenolic compounds and flavonoids decreased when the sourdough was dried (1.5 to 2.0 mg/g of quercetin); however, an increase in bioactive compounds was observed after reactivation, with the treatments with AB recording the highest values (2.5 mg/g). The DPPH and ABTS tests showed that T10 had the highest activity (25% and 23%, respectively). The OPA results showed an increment in amino acid content (2.0 mg lysine/g), indicating proteolysis. The fermentation curves showed that leavening time was achieved after 600 min of fermentation. AB addition did not affect the viscosity of the sourdough rolls. Sourdough with added AB and L. lactis provided a novel approach to achieve more sustainable baked goods. The drying process decreased the sourdough’s bioactive compounds, which were recovered after reactivation. Full article

This study aimed to evaluate the effects of fermented chive (Allium schoenoprasum) with Lactobacillus plantarum 1582 (FC) as an alternative to antibiotics for controlling Escherichia coli infection in broiler chickens. A total of 250 J-Dabaco male chickens were allocated into five experimental groups: NC (negative control), PC (positive control), FC1 (1% FC), FC3 (3% FC), and AB (antibiotic treatment). The PC, FC1, FC3, and AB groups were challenged with E. coli ExPEC_A338 on day 8 and monitored until day 35. The results indicated that FC supplementation, particularly at 3% (FC3 group), significantly improved body weight gain, feed intake, the survival rate, and the production efficiency index (PEI). The FC3 group exhibited optimal performance, potentially due to enhanced immune responses, as evidenced by higher IgA and IgG levels, and favorable cytokine regulation. Additionally, FC maintained intestinal epithelial integrity by upregulating tight junction proteins (ZO-1, Claudin-2) and reducing inflammatory responses (IFN-γ, TNF-α). Furthermore, FC3 demonstrated the ability to inhibit pathogenic bacteria (Salmonella spp., E. coli), promote beneficial Lactobacillus spp., and enhance intestinal mucosal morphology (villus height and crypt depth). These findings suggest that FC supplementation, particularly at 3%, is a promising natural alternative to antibiotics for controlling E. coli infections in broiler production. Full article

This study investigated the beneficial effects of individual and co-inoculation with Lactobacillus delbrueckii subsp. lactis N102 and Lactobacillus sakei H1-5 on improving safety parameters, sensory characteristics, and non-volatile metabolite profiles in dry-fermented sausages. Comprehensive analyses were conducted throughout the 20-day maturation period (0, 6, 13, 16, and 20 days), including physicochemical monitoring (moisture content, malondialdehyde (MDA) levels, biogenic amine concentrations, and sodium nitrite residues); sensory evaluation (color parameters and textural properties); and ¹H NMR-based metabolomic profiling. Key findings revealed strain-specific advantages: the N102 inoculation significantly delayed lipid oxidation, achieving the lowest final MDA concentration (4.5 mg/kg) among all groups. Meanwhile, H1-5 supplementation notably improved color attributes (a*/b* ratio = 1.34). The co-inoculation strategy demonstrated synergistic effects through (1) accelerated acidification (pH 5.3 by day 6); (2) enhanced textural properties (significantly increased hardness and elasticity vs. control); (3) optimized water distribution (free water reduced to 0.56% with 64.73% immobilized water); and (4) a significant reduction in sodium nitrite residues (70% decrease) and complete elimination of phenylethylamine (total biogenic amines: 702.94 mg/kg). ¹H NMR metabolomics identified 30 non-volatile metabolites, and the co-inoculation significantly increased the amount of essential amino acids (leucine, isoleucine), flavor-related compounds (glutamic acid, succinic acid), and bioactive substances (gooseberry, creatine). These metabolites enhanced antioxidant capacity, freshness, and nutritional value. Our findings demonstrate that strategic co-cultivation of food-grade lactobacilli can synergistically enhance both the techno-functional properties and biochemical composition of fermented meat products, providing a viable approach for quality optimization in industrial applications. Full article

Beer, the most popular alcoholic beverage, poses health risks for individuals with gout and hyperuricemia due to its high purine content. Herein, we identified a novel purine nucleoside phosphorylase (AbPNP) from the edible mushroom Agaricus bisporus and heterologously expressed it in Pichia pastoris. The recombinant AbPNP exhibited optimal activity at 60 °C and pH 7.0, retaining >80% activity at pH 6.0–9.0 and >85% activity after 3 h at ≤60 °C. Kinetic analysis revealed high catalytic efficiency (kcat/Km = 2.02 × 10⁶ s⁻¹⋅M⁻¹) toward inosine, with strong resistance to metal ions except for Co²⁺ and Cu²⁺. The application of AbPNP (1.0–5.0 U/mL) during wort saccharification reduced purine nucleosides by 33.54% (from 151.53 to 100.65 mg/L) while increasing yeast utilization of free purine bases. The resulting beer showed improved fermentation performance (alcohol content increased by 3.6%) without compromising flavor profiles. This study provides the food-grade enzymatic strategy for low-purine beer production, leveraging the GRAS status of both A. bisporus and P. pastoris. Full article

The growing advocacy for greener climates, coupled with increasing global energy demand driven by urbanization and population growth, highlights the need for sustainable solutions. Repurposing food wastes as substrates offers a promising approach to enhancing cleaner energy generation and promoting a circular economy. This study investigated the potential of spent coffee grounds (SC) and biosolids cake (BS) from tea wastes as substrates for producing valuable fuels and chemicals through acetone–ethanol–butanol (ABE) fermentation. Clostridium beijerinckii NCIMB 8052 was used to ferment 100% and 50% hydrolysates derived from Parr-treated enzyme-hydrolyzed (PEH, PEH50), Parr-treated non-hydrolyzed (PNEH, PNEH50), and non-Parr-treated hydrolyzed (NPEH) SC wastes, as well as enzyme-hydrolyzed (BSH, BSH50) and non-hydrolyzed BS wastes (NBH, NBH50). Fermentation of unmodified hydrolysates by C. beijerinckii was poor. Following CaCO₃ modification of SC and BS hydrolysates, ABE titer, yield, and productivity increased, with the highest values obtained with PEH50 and NBH. Specifically, CaCO₃ modification of SC hydrolysates led to increased butanol titer, yield, and productivity in PEH50, while the NBH exhibited higher butanol yield and productivity than the non-CaCO₃-modified hydrolysates. Additionally, H₂ gas production with PEH50 and NBH was 1.41- and 1.13-fold higher, respectively, than in other hydrolysates. These findings suggest that SC and BS hydrolysates can be valorized to butanol and hydrogen gas and, thereby, can contribute to global food wastes management, energy sustainability, and cost-effective biofuel production. Full article