Search Results (149)

With the increasing consumer demand for high-quality lamb, crossbreeding has become a key technology for improving the production performance and meat quality of sheep. To evaluate the meat quality advantages and characteristics of Suffolk (SFK) and Hu sheep (HH) and their F₁ crossbreds (SH), thirty-six 3-month-old male lambs of SFK (n = 12), HH (n = 12), and SH (n = 12) were selected and raised in individual pens under the same nutritional and management conditions. After standardized feeding until 6 months of age, the Longissimus dorsi muscle was collected to determine meat quality traits, amino acid and fatty acid profiles, and volatile flavor compounds. The results indicated that the L*, a* and b* values of the SH group were significantly lower than those of the parental breeds (p < 0.05), with tenderness being intermediate between the two parent breeds. Notably, drip loss and cooking loss were significantly lower in the SH group (p < 0.05), indicating superior water-holding capacity. In terms of amino acid profiles, the contents of non-essential amino acids (NEAAs) and sweet-tasting amino acids in the SH group were significantly higher than those of the parent breeds (p < 0.05), with the overall profile meeting the FAO/WHO ideal protein pattern. Analysis of fatty acid profiles revealed that the SH group had significantly lower total saturated fatty acids (SFAs) (p < 0.05) and significantly higher levels of functional fatty acids (such as CLA), resulting in a significantly higher UFAs (unsaturated fatty acids)/SFAs (saturated fatty acids) ratio (p < 0.05) and superior nutritional value of fat. Furthermore, 32 volatile flavor compounds were detected in the SH group; among them, key aroma-active compounds such as isoamyl formate, 3-methyl-1-butanol, and acetoin were significantly higher than in the parental breeds (p < 0.05), contributing to a unique flavor profile. Consequently, this study systematically reveals the advantages of Suffolk × Hu F₁ crossbreds in terms of meat quality, nutritional value, and flavor characteristics, providing fundamental data for the optimization of crossbreeding systems, breeding selection, and the quality improvement of sheep meat products. Full article

Sporulation represents a complex metabolic reprogramming process in bacteria. In this study, we used CRISPR-Cpf1 to knock out spoIIE and rsfA in Bacillus licheniformis. The ΔspoIIE strain completely lost sporulataion capacity, while ΔrsfA showed a 25% reduction. Although viable cell counts decreased by 80.7% and 45.7%, respectively, glucose consumption and 2,3-butanediol synthesis remained unchanged, and acetoin synthesis increased by 19% in ΔspoIIE. Per-cell metabolic rates were significantly enhanced: glucose uptake increased 2.7–3.4-fold, acetoin synthesis 2.3–4.2-fold, 2,3-butanediol synthesis 1.7-fold, and heterologous protein expression 10–15-fold. These findings demonstrate that blocking sporulation liberates metabolic resources and enhances the specific productivity of vegetative cells, providing a strategy for engineering high-performance B. licheniformis cell factories. Full article

Cheese ripening is slow and costly, driving interest in accelerating maturation. This study aimed to isolate a safe, efficient adjunct starter from traditional Sichuan yak yoghurt, a niche rich in stress-adapted lactic acid bacteria. From 295 isolates, 15 strains tolerant to high salt, low pH, and low temperature were selected. Using acidification, autolysis, proteolysis, and peptidase activity as indices, principal component analysis identified Limosilactobacillus fermentum 270 as the best candidate. Phenotypic assays showed no haemolysis, gelatin liquefaction, indole production, or amino acid decarboxylase activity. Whole-genome sequencing confirmed species identity and revealed 52 protease/peptidase genes, complete pathways for diacetyl/acetoin biosynthesis and branched-chain amino acid conversion, and no functional biogenic amine synthesis genes. Stress-related genes (F-ATPase, glycine-betaine transport, cold-shock proteins) support cheese adaptability. Antibiotic resistance gene homologs were mainly chromosomal and unlinked to mobile genetic elements; a functional CRISPR-Cas system lowers horizontal transfer risk. The strain was developed as a freeze-dried direct-vat starter (97.3% viability). Orthogonal optimisation of yak Gouda cheese-making defined best conditions: 0.018% adjunct, 45 min acidification, pH 5.8, and 30% curd washing. L. fermentum 270 thus combines proteolytic, flavour-enhancing, genetic safety, and processing traits, offering a promising adjunct for accelerated cheese ripening. Full article

Microbial volatile organic compounds (VOCs) mediate rhizosphere plant-microbe interactions, yet their integrated effects on plant microbiome assembly and host transcriptional regulation remain unresolved. Here we address this gap by investigating how two common VOCs, acetoin (AC) and 2,3-butanediol (BD), influence growth, rhizosphere communities, and root gene expression in the medicinal plant Pseudostellaria heterophylla using a split-pot system. Bacterial and fungal communities were monitored across three developmental stages via amplicon sequencing, alongside root transcriptome profiling during tuber enlargement. Contrasting with widely reported growth-promoting effects of microbial VOCs, both compounds significantly reduced tuber number and biomass. Bacterial communities remained taxonomically stable, shaped primarily by species replacement, with modest VOC responses but clear shifts across developmental stages. Fungal communities exhibited marked compositional restructuring and greater treatment sensitivity, particularly under BD. Neutral community modeling indicated predominantly stochastic bacterial assembly, while fungal assembly—especially under BD—showed stronger influence of deterministic processes. BD associated with broader transcriptional reprogramming than AC, including downregulation of photosynthesis, specialized metabolism, and defense pathways. Cross-omics network analysis revealed discriminant genera (e.g., Granulicella, Harposporium) that correlated strongly with host genes involved in stress response, development, and epigenetic regulation, with fungal taxa showing tighter associations with host expression than bacteria. Together, these findings establish a mechanistic framework for how microbial VOCs shape rhizosphere communities and host responses, with implications for microbiome-based strategies in medicinal plant cultivation. Full article

Patulin (PAT) is a fatal mycotoxin that exerts serious threats to human and animal health. Biodegradation of PAT is considered to be one of the promising ways for controlling its contamination. In this study, Lactiplantibacillus plantarum 6076 (LP 6076) with reliable removal efficiency on PAT was screened out from three lactic acid bacteria (LAB) strains. It was found that the PAT was eliminated through degradation by LP 6076, and the intracellular proteins played a crucial role in PAT degradation with the induction of PAT. The proteomic analysis showed that the response of LP 6076 to PAT was by a concerted effort to repair DNA damage, in parallel to adaptive changes in cell wall biosynthesis and central metabolism. Eleven differentially expressed proteins with high fold changes were picked out and identified as PAT degradation candidate enzymes. The 3D structures of the candidate enzymes were predicted, and molecular docking between the enzymes and PAT was performed. Five enzymes, including Acetoin utilization AcuB protein (AU), GHKL domain-containing protein (GHLK), Dihydroneopterin aldolase (DA), YdeI/OmpD-associated family protein (YDEL), and Transcription regulator protein (TR), could dock with PAT with lower affinity and shorter distance. Through molecular docking analysis, DA was ultimately identified as a potential key degrading enzyme. The choice of DA was substantiated by its superior combination of strong binding affinity and a productive binding pose with PAT. VAL84 and GLN51 residues of DA were likely the active sites, forming four hydrogen bonds with PAT. Our study could accelerate the commercial application of biodegradation toward PAT decontamination. Full article

Listeria monocytogenes (LM) contamination constitutes a paramount global threat to food safety, necessitating the urgent development of advanced, rapid, and non-destructive detection methodologies to ensure food security. This study successfully synthesized Bi₂WO₆ nanoflowers through optimized feed ratios of raw materials and further functionalized them with noble metal Au to construct a high-performance Au-Bi₂WO₆ composite nanomaterial. The composite exhibited high sensing performance toward acetoin, including high sensitivity (R_a/R_g = 36.9@50 ppm), rapid response–recovery kinetics (13/12 s), and excellent selectivity. Through UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) and X-ray photoelectron spectroscopy (XPS) characterizations, efficient electron exchange between Au and Bi₂WO₆ was confirmed. This electron exchange increased the initial resistance of the material, effectively enhancing the response value toward the target gas. Furthermore, the chemical sensitization effect of Au significantly increased the surface-active oxygen content, promoted gas–solid interfacial reactions, and improved the adsorption capacity for target gases. Compared to conventional turbidimetry, the Au-Bi₂WO₆ nanoflower-based gas sensor demonstrates superior practical potential, offering a novel technological approach for non-destructive and rapid detection of foodborne pathogens. Full article

This study evaluated the effects of different concentrations (0.25%, 0.5%, and 1.0% w/w) of highly purified (90%) β-glucan (scleroglucan—SCGL) produced by Sclerotium rolfsii on the physicochemical, rheological, microbiological, and sensory properties of full-fat yoghurt (3.2% fat). The fermentation dynamics, titratable acidity, apparent viscosity, hardness, adhesiveness, colour, microstructure, and volatile compound profiles of the studied yoghurts were analysed. The addition of SCGL increased gel hardness and viscosity, while preserving its pseudoplastic flow behaviour (n = 0.10–0.15). In samples containing 1.0% SCGL, yield stress (τ₀) increased from 0 Pa in the control to 739 Pa after 28 days of storage, pointing to the formation of a dense protein–polysaccharide network. The analysed polysaccharide slowed down lactose hydrolysis and acidification, but increased the counts of Streptococcus thermophilus (7.7 log CFU·g⁻¹) compared to the control (5.8 log CFU·g⁻¹). The volatile compound analysis showed increased acetaldehyde (5.6 mg·L⁻¹) and diacetyl (5.0 mg·L⁻¹) levels and reduced acetoin (~1.0 mg·L⁻¹) concentration, which enhanced the intensity of the buttery aroma. The sensory evaluation revealed that yoghurts containing 1% SCGL had the most desirable smooth consistency and a balanced, fresh aroma, whereas yoghurts with lower SCGL concentrations (0.25–0.5%) were characterised by a mealy mouthfeel and thinner consistency. Scleroglucan proved to be an effective natural stabiliser and flavour modulator that improved the structure, stability, and sensory quality of full-fat yoghurts. Full article

Chuanbai Rex (CR) and New Zealand white (NZ) rabbits are highly popular and widely produced for meat consumption in Sichuan, China. But comparative studies on nutritional and sensory qualities of meat from two breeds are still lacking. This study integrated lipidomic and volatilomic approaches to elucidate the breed-specific differences in the longissimus dorsi between CR and NZ (n = 5 per breed). Analysis of fatty acid composition revealed that CR had lower content of PUFA but with a more balanced n-6/n-3 PUFA ratio compared to NZ. LC-MS-based lipidomics identified 52 significantly different lipids between the two breeds, and CR had higher levels of phospholipids and sphingolipids, while NZ was richer in triglycerides and diglycerides. SPME-GC-MS analysis identified a total of 140 VOCs, including primarily aldehydes (>50%), alcohols (<20%), and hydrocarbons (<15%). CR contained unique aroma compounds such as acetoin and 2-(E)-heptenal, while NZ had more of nonanal and pentadecane. Pearson correlation analysis performed between differential lipid metabolites and characteristic VOCs showed that 22 lipid biomarkers were significantly correlated with seven key VOCs, suggesting breed-distinct pattern for flavor formation. Albeit a small sample size, this study provides preliminary insights into biochemical mechanisms determining rabbit meat quality and offers a scientific basis for developing premium rabbit meat products tailored to consumer preferences. Full article

Broad bean paste (BBP), a traditional Chinese fermented condiment, often suffers from inconsistent quality during spontaneous fermentation. In this study, Weissella confusa KUST3424 and Bacillus subtilis KUST4527 were isolated from BBP and evaluated as starter cultures, either individually or in combination. Flavor characteristics were analyzed using an electronic nose, electronic tongue, and GC–MS combined with odor activity value (OAV) calculations. Results showed that 13 key flavor compounds with OAVs greater than 1 were identified as major contributors to the overall aroma of fermented BBP juice (FBPJ). Moreover, inoculated groups exhibited distinct flavor profiles compared with natural fermentation, with the co-culture producing the most pronounced improvements. The mixed fermentation markedly enhanced desirable alcohols and esters, including significant increases in isoamyl alcohol (125.87%), 2-furanmethanol (128.91%), phenethyl alcohol (354.06%), and 4-vinylguaiacol (150.99%). In addition, compounds such as acetoin, guaiacol, ethyl hexanoate, and ethyl benzoate were newly generated in the co-culture group, while the diversity and total content of esters increased significantly from 0.52% to 9.69%. These findings demonstrate that the combined use of W. confusa KUST3424 and B. subtilis KUST4527 as starter cultures can effectively enhance the complexity and overall quality of BBP flavor. This co-culture strategy shows promise for enhancing flavor control and consistency in industrial-scale BBP production. Full article

Debaryomyces hansenii has the potential to enhance the flavor profile of traditional fermented meat products. This study investigates the impact of the D. hansenii LY090 strain on the microbial community, lipidome, flavor profiles, and sensory properties of Sichuan bacon. Inoculation with LY090 significantly inhibited the relative abundance of other yeasts, except for Debaryomyces, and altered bacterial community composition. The presence of LY090 led to a notable reduction (p < 0.05) in the levels of ceramide and phosphatidylcholine, resulting in an excessive inhibition of lipid degradation. This further affected the development of flavor and color in Sichuan bacon. However, the concentrations of aldehydes (249.80 μg/kg), ethyl 3-methylbutyrate (81.01 μg/kg), and acetoin (223.91 μg/kg) were all found to be abundant, and the bacon achieved the highest overall acceptance scores when inoculated with both LY090 and commercial starter culture FAST301. Correlation analysis indicated that the differential metabolites exhibited a stronger association with the yeast community, which plays a vital role in the flavor development of Sichuan bacon. These detailed investigations provide meaningful implications for D. hansenii LY090 implementation strategies in the Sichuan bacon industry. Full article

Korean melon (K-melon, Cucumis melo L. var. makuwa) is a key horticultural crop in the Republic of Korea, but its short shelf life restricts long-distance export. This study evaluated the modified atmosphere (MA) films of varying oxygen transmission rates (OTR) at controlled atmosphere (CA) storage under real maritime export conditions to Vietnam. In the non-permeable OTR 0 (Control) treatment, internal O₂ rapidly declined below the anaerobic compensation point (1.67% at 10d and 0.47% at 10+3d) while CO₂ accumulated to 32–36%. This ultra-low oxygen environment induced anaerobic metabolism, evidenced by strong accumulation of fermentative metabolites such as lactic acid, acetoin, and 2,3-butanediol, along with glucose/fructose retention and increases in alanine and γ-Aminobutanoic acid (GABA). These changes disrupted glycolysis and the Tricarboxylic acid cycle (TCA), consistent with CA shock, and were accompanied by rind blackening, elevated weight loss, and hue angle shifts toward yellow-orange. By contrast, OTR 10,000 and OTR 30,000 films significantly suppressed weight loss and color changes. Partial least squares-discriminant analysis (PLS-DA) identified volatile organic compounds, namely acetoin, 2,3-butanediol, and hexanal, as key discriminant metabolites, with OTR 30,000 clearly separated from other treatments at 10+3d, indicating minimal fermentation and oxidative stress. Microbial assays revealed a dose-dependent reduction in bacterial counts with increasing OTR, while fungal growth was most strongly suppressed under OTR 10,000. Overall, OTR 30,000 maintained the lowest and most stable levels of stress-related metabolites, minimized microbial proliferation, and preserved metabolic stability throughout shipping. This study provides the first quantitative evidence of anaerobic metabolic transition and primary metabolite accumulation in K-melons under actual export trials. The findings demonstrate that optimizing MA film permeability, particularly OTR 30,000 films, offers a practical and cost-efficient strategy to extend shelf life, maintain quality stability, and enhance the global export potential of K-melons. Full article

The phyllosphere, the aerial part of plants, serves as a crucial habitat for diverse microorganisms. Phyllosphere bacteria can activate protective mechanisms that help plants resist disease. This study focuses on isolating and characterizing phyllosphere bacteria from cucurbits to evaluate their potential in controlling Colletotrichum orbiculare, a pathogen causing anthracnose in cucumbers. Among the 76 bacterial isolates collected, 11 exhibited strong antagonistic effects against C. orbiculare in vitro. Morphological and 16S rRNA analyses identified these isolates as different Bacillus species, including B. vallismortis, B. velezensis, B. amyloliquefaciens, and B. subtilis. These bacteria demonstrated essential plant-growth-promoting and biocontrol traits, such as motility, biofilm formation, phosphate solubilization, nitrogen fixation, and the production of indole acetic acid. Most of the bacterial strains also produced biocontrol compounds such as ammonia, acetoin, siderophores, hydrogen cyanide, chitinase, protease, lipase, and cellulase. The application of these bacteria significantly enhanced cucumber growth in both non-manured and organically manured soils, showing improvements in root and shoot length, chlorophyll content, and biomass accumulation. Additionally, bacterial treatments effectively reduced anthracnose severity, with isolates GL-10 and L-1 showing the highest disease suppression in both soil types. Colonization studies showed that phyllobacteria preferentially colonized healthy leaves over roots and diseased tissues, and they were more effective in manure-amended soils. These results suggest that Bacillus phyllobacteria have strong potential as sustainable bio-stimulants and biocontrol agents, offering an effective approach for enhancing cucumber growth and disease control under both fertilized and unfertilized soil conditions. Full article

To achieve the large-scale, low-cost preparation of acetaldehyde lyase (ALS), elastin-like polypeptides (ELPs) as non-chromatographic purification tags were employed to develop an ELP-ALS fusion protein in Escherichia coli. Induction expression results demonstrated that the ELPs tag efficiently improved the soluble expression of the ALS enzyme. Through two rounds of inverse transition cycling (ITC), highly pure ELP-ALS was obtained with an enzyme recovery rate of 85.77%, outperforming Ni²⁺-affinity chromatography (66.80%). The comparative analysis of enzymatic properties revealed that ELP fusion markedly improved the stability and substrate tolerance of the ALS enzyme. Kinetic parameter analysis under identical conditions showed that ELP-ALS possessed a V_max of 15.25 U/mg and a k_cat/K_m of 73.05 s⁻¹·M⁻¹, representing 1.86-fold and 2.97-fold improvements over His-ALS, respectively. Fed-batch reaction using ELP-ALS and acetaldehyde as biocatalyst and substrate, respectively, yielded 95.92 g/L acetoin with 49.32% increase compared to His-ALS (64.24 g/L). These results demonstrated the application potential of ELP-ALS as a promising biocatalyst for acetoin production from acetaldehyde due to its lower preparation cost, higher biocatalytic efficiency, better stability, and substrate tolerance. Full article

The most notable effects of climate change on wine production are higher alcohol levels, lower acidity and changes to the regions suitable for growing grapes. One solution to acidity problems is the use of Lachancea thermotolerans, a yeast that produces lactic acid during fermentation, albeit at the cost of reduced aromatic complexity. A novel approach to addressing this problem is to use L. thermotolerans to produce wines with a very high acidity, regardless of other parameters, for subsequent blending with a control wine with a naturally low acidity. This achieves a balanced acidity while retaining the organoleptic characteristics of the control wine. This is a novel idea, as L. thermotolerans is not usually used in the final wine. However, the objective from the beginning is to create a blend that combines the best characteristics of the control wine with the improved acidity provided by L. thermotolerans. Base wines were produced by inoculating Saccharomyces cerevisiae 20, 40, or 60 h after inoculating L. thermotolerans. Base wines generally show an increase in lactic acid content and a decrease in certain key aromatic compounds, such as isoamyl acetate, 2-phenylethyl acetate, ethyl hexanoate, and ethyl octanoate. Concentrations of other compounds such as acetaldehyde and higher alcohols also increase. The base wines were then blended with a low-acidity control wine. The resulting blends exhibited higher acidity than the control wine, as well as better aromatic profiles, particularly regarding fruity and green fruit aromatic compounds, compared to base wines. Ten volatile compounds have been correlated with lactic acid production by L. thermotolerans, namely ethyl hexanoate; ethyl butanoate; 2-methylbutanol; ethyl heptanoate; isoamyl acetate; acetaldehyde; isobutanol; 2-phenylethanol; dodecanol; and acetoin. The first five are negatively correlated and the rest are positively correlated. Lastly, sensory analysis revealed that the blends achieved the best balance between acidity and aroma, making them the most popular with tasters. Full article

Dates (Phoenix dactylifera L.) are nutrient-rich fruits with health-promoting properties and broad applications in the food and beverage industries. This study analyzes the chemical properties and volatile profile of fermented date products—juice, alcoholic derivative, and vinegar—to develop a high-quality vinegar with distinct sensory traits. Using HS-SPME-GC-MS, about 50 volatile compounds were identified across six major chemical classes. Juice processing significantly increased volatile release, especially fusel alcohols and furanic aldehydes, due to thermal and mechanical disruption. Fermentation further modified the volatilome, with increased esters and acids in alcoholic and vinegar products. Vinegar was characterized by high levels of acetic acid, fatty acids, phenols, and acetoin (855 mg/L), indicating active microbial metabolism. Ethanol and acidity levels met international standards. Total phenolic content rose from juice (138 mg/L) to vinegar (181 mg/L), reflecting microbial enzymatic activity and acid-driven extraction. These results highlight the metabolic complexity, sensory richness, and functional potential of date-derived fermented products while promoting sustainable use of underutilized fruit resources. Full article