Search Results (768)

Traditional cheese products harbor complex microbial communities that influence their quality and safety. However, the effects of processing scale and manufacturing stage on the microbial profile of hurood, a traditional Mongolian cheese, remain poorly understood. This study examined microbial indicators, community composition, and succession dynamics across four manufacturing stages (raw milk, yogurt, whey, and hurood) and three processing scales (pastoral household, workshop, and factory) using plate counting and 16S rRNA gene amplicon sequencing. Twenty-four samples were collected from Xilin Gol, Inner Mongolia. Total aerobic plate counts and coliform counts decreased significantly from raw milk (7.30 and 4.49 log CFU/g, respectively) to hurood (2.02 and 0.34 log CFU/g, respectively; p < 0.05), reflecting progressive microbial reduction through acidification and thermal treatment, whereas yeast counts remained stable across stages. Firmicutes dominated the fermented stages, with Lactococcus and Lactobacillus as the predominant genera. Whey harbored an exceptionally high abundance of Acetobacter (21.6%), highlighting its valorization potential. Factory-scale production yielded the lowest mold and coliform counts in finished products despite higher initial coliform levels in industrial raw milk, reflecting the effectiveness of standardized hygiene management. In contrast, workshop-scale samples exhibited a higher relative abundance of environmental indicator bacteria, suggesting a comparatively elevated contamination risk this intermediate production scale. PICRUSt2-based functional predictions indicated stage-specific metabolic potential, including predicted enrichment of pyruvate and fatty acid metabolism in yogurt, amino acid metabolism in whey, and vitamin B6 metabolism in hurood. These findings provide a systematic microbial baseline for hurood, identify scale-specific microbiological risk profiles, and offer a foundation for targeted hygiene control and standardized production strategies. Full article

As a precious indigenous goose resource in China, the Zhedong white goose occupies an essential position in the domestic goose industry. However, this breed spontaneously enters a prolonged non-laying period of over two months per year, which greatly limits egg production capacity and restricts the economic development of the goose industry. Herein, this study systematically compared serum physiological indices and serum and fecal metabolome, as well as fecal microbial communities, between laying and non-laying Zhedong white geese, aiming to reveal the key regulatory mechanisms underlying reproductive stage transition. Physiological analyses indicated that non-laying geese had higher serum levels of GnRH, PRL, APOA, and T-AOC, whereas the concentrations of LH, E₂, TNF-α, IL-1, and calcium were significantly reduced; FSH, PROG, and BA levels showed no significant differences between the two groups. Metabolomic analysis identified 277 upregulated and 403 downregulated DAMs in feces, and 386 DAMs in serum. The shared enriched pathways across serum and fecal samples encompassed arginine biosynthesis, histidine metabolism, and pantothenate and CoA biosynthesis, as well as steroid hormone biosynthesis. A total of 120 DAMs overlapped in two specimens, and the non-laying geese presented pronounced depletion of tryptophan-derived metabolites and steroid hormone-related metabolites. Metagenomic results showed no significant difference in gut microbial alpha diversity between groups, while their microbial community structures were clearly differentiated. A total of 774 upregulated and 854 downregulated microbial species were screened in non-laying geese, and these differential microbes were primarily enriched in pathways associated with reproductive hormone signaling, steroid biosynthesis and energy metabolism. Multi-omics correlation analysis verified close associations between differential microbes and reproductive-related metabolites. Certain probiotic strains, including Pediococcus pentosaceus and Lactococcus raffinolactis, were positively correlated with steroid hormones and tryptophan metabolites, and their abundances declined obviously in the non-laying stage. Collectively, this study elaborates the holistic changes in serum biochemistry, gut metabolome and microbiome in geese at different reproductive stages. The dysregulation of amino acid and steroid hormone metabolism, combined with the loss of beneficial intestinal microbes, jointly induces the non-laying phenotype. This study provides new perspectives for understanding the gut–reproductive axis and supplies promising biomarkers to improve the laying performance of geese. Full article

This study evaluated Lactococcus lactis RDN-1 and its inorganic selenium-enriched derivative in hybrid sturgeon, focusing on growth performance, immune responses, and intestinal health. A 21-day feeding trial was conducted with four groups: control (CK), L. lactis RDN-1 (R), inorganic selenium-enriched L. lactis RDN-1 (RX), and enrofloxacin (E). All supplemented groups exhibited significantly improved weight gain. The R group attained the highest levels of most essential and total amino acids, whereas the RX group achieved the highest methionine content. In contrast, the E group exhibited significantly lower levels of most amino acids compared to the R and RX groups. The R group suppressed the abundance of Proteobacteria while enriching beneficial genera such as Lactococcus, thereby enhancing functional capacities related to energy metabolism, amino acid biosynthesis, and signal transduction. The RX group promoted Firmicutes and Bradyrhizobium, and exhibited superior functional characteristics in antioxidant capacity and secondary metabolite biosynthesis. Moreover, the RX group down-regulated IL-6, demonstrating a balanced immunomodulatory effect with anti-inflammatory potential. In conclusion, L. lactis RDN-1 and its selenium-enriched derivative represent promising antibiotic alternatives. L. lactis RDN-1 alone offers more comprehensive effects, whereas inorganic selenium supplementation partially impairs its overall performance but achieves more accurate immune regulation. This work provides a scientific foundation for the precise application of L. lactis. Full article

In Mexico, cheese whey (CW) is commonly treated as a dairy wastewater despite its high lactose and nutrient content. This study evaluated cheese whey (CW) and ultrafiltered cheese whey (UF-CW) as low-cost substrates for the cultivation of the probiotic strains Lactobacillus acidophilus and Lactococcus lactis. The proposed bioprocess simultaneously enables the production of probiotic biomass and lactic acid, a high-value platform chemical with broad applications in the food, pharmaceutical, and biopolymer industries. In the first experimental trials, in which CW and UF-CW were used solely as media, fermentations lasted 36 h at 30 and 37 °C, with initial pH levels of 5 and 7. CW demonstrated a greater capacity to support the growth of lactic acid bacteria. Thus, to increase the fermentative capability of UF-CW, it was supplemented with yeast extract (YE) or corn steep liquor (CSL), and CaCO₃ was added to stabilize pH, as low pH values inhibit growth and lactic acid production. The proposed strategy notably improved microbial growth in UF-CW, increasing Lc. lactis and L. acidophilus populations from 8.3 and 8.2 Log₁₀ CFU/mL to 9.3 Log₁₀ CFU/mL, respectively. The findings suggest that dairy wastewater can be effectively repurposed as a low-cost cultivation medium for these bacteria. ASPEN simulation analyses demonstrated that lactose conversion efficiency and final product concentration were key factors affecting process performance and economic feasibility. Among the evaluated scenarios, a 45% lactose-to-lactic acid conversion yielded the most economically favorable process performance compared with conversions of 10% and 25%. Future research should focus on enhancing fermentation yields and adopting more efficient downstream recovery techniques. Full article

Bacterial diseases cause significant losses in the aquaculture of Amazonian fishes (Arapaima gigas, Brycon amazonicus, and Colossoma macropomum). Lactococcosis-causing bacteria (LCB) have emerged as important pathogens in global aquaculture, and although they have already been isolated from these fish species, their pathogenic role remains unconfirmed. This study evaluated the susceptibility of three Amazonian fish species to Lactococcus spp. through experimental infection and performed a detailed examination of the associated pathological damage. Lactococcus formosensis, L. garvieae, and L. petauri strains were used to intracoelomically infect juvenile Amazonian fish. Following infection, the fish were monitored for 15 days to evaluate clinical signs and mortality. Clinical signs were observed in the L. garvieae-challenged A. gigas, with one fish dying at five days post-infection. The remaining experimental animals, regardless of fish species, survived the challenge. All mortalities and surviving fish at the end of the trial underwent bacteriological and histopathological examinations. Bacteriological examination confirmed bacterial re-isolation from asymptomatic animals in the L. garvieae-challenged A. gigas (2/7) and L. formosensis-challenged C. macropomum (3/7) groups using MALDI-TOF MS and multiplex qPCR analysis. No bacterial growth or histological alterations were observed in the control groups or in the groups infected with L. petauri. Microscopic examination revealed L. garvieae-induced fibrinoid-necrotic hepatitis, lymphohistiocytic myocarditis, and myositis in diseased or asymptomatic A. gigas, while L. formosensis caused lymphohistiocytic pericarditis in surviving C. macropomum. These findings provide preliminary evidence suggestive of susceptibility of A. gigas and C. macropomum to infection by L. garvieae and L. formosensis, respectively, highlighting their potential to act as asymptomatic carriers. Furthermore, the histopathological findings were suggestive of species-associated lesion patterns of piscine lactococcosis in Amazonian fish, rather than indicative of high mortality. Full article

This study aimed to screen high-yield and high-quality sorghum–sudangrass hybrid varieties suitable for popularization and cultivation in the Hulunbuir region through a comprehensive evaluation of silage fermentation quality and bacterial community. Comparative analyses were conducted on six sorghum–sudangrass varieties, namely, sorghum–sudangrass hybrid 3 (SS1), sorghum–sudangrass hybrid 4 (SS2), sorghum–sudangrass hybrid 5 (SS3), sorghum–sudangrass hybrid 7 (SS4), sorghum–sudangrass hybrid 8 (SS5), and Super Sugar–Dwarf Sorghum (SS6). The harvested sorghum–sudangrass at the late milk stage was chopped, vacuum-sealed in polyethylene bags (30 cm × 40 cm), and subjected to 60 days of ensiling fermentation. The results revealed significant differences among different varieties (p < 0.05). SS2 achieved the highest fresh herbage yield of 78.26 t/hm², while the fresh yield of SS4 was 57.39 t/hm², approximately 26.7% lower than that of SS2. However, SS4 exhibited superior quality, with the thickest stem diameter of 20.26 mm (p < 0.05). It exhibited the highest crude protein content, reaching 5.72% DM; its silage pH was relatively low, at only 3.71 (p < 0.05); its fiber content was significantly reduced (acid detergent fiber, ADF = 40.03% DM, p < 0.05); and it was rich in Lactococcus and Lactobacillus (p < 0.05). The ensiling process of SS4 highly significantly decreased bacterial diversity (p < 0.01) and shifted the dominant bacterial phylum from Proteobacteria to Firmicutes. Functional prediction indicated that the bacterial community of SS2 possessed the highest predicted abundance of functional genes related to cellulase and beta-glucosidase (p < 0.05). Our findings suggest that SS2 should be prioritized for production systems aiming for maximum biomass accumulation, whereas SS4 is recommended as a superior variety for high-quality animal nutrition systems where fermentation stability and nutrient preservation are paramount. Full article

The quality and flavor of probiotic fermented milk are highly dependent on the strain composition of the starter culture and their metabolic interactions. Although constructing a multi-strain system is an effective strategy for enhancing product quality, traditional formulation methods rely heavily on empirical approaches and lack mechanistic guidance. Herein, this study utilized genome-scale metabolic models (GEMs) to rationally design a multi-strain co-fermentation system. The results demonstrated that the GEM-predicted optimal system, comprising Lacticaseibacillus paracasei subsp. paracasei 63 (L. paracasei subsp. paracasei 63) and Lactococcus cremoris 290 (Lc. cremoris 290), significantly reduced the curd time by approximately 44.0% and 71.0% compared to the L. paracasei subsp. paracasei 63 and Lc. cremoris 290 monocultures, respectively. Furthermore, the co-fermented milk exhibited a 4.3-fold increase in apparent viscosity relative to the 290 single-strain group and achieved a significantly higher diacetyl concentration (1.98 ± 0.09 mg/L), representing a 2.8-fold enhancement. Volatile flavor profiling and untargeted metabolomics provided suggestive evidence supporting the GEM-predicted cross-feeding mechanisms, particularly within the arginine and pyruvate metabolic pathways. This study offers a solid theoretical foundation and practical guidance for the rational design of synthetic microbial communities to develop high-quality fermented dairy products with optimized flavor and functional properties. Full article

Background/Objectives: The aquaculture industry represents a fundamental food sector. One of the main limiting factors for this sector is related to bacterial diseases, for which antibiotics have been widely used worldwide for decades. In recent years, a more conscious approach to the use of antimicrobials within the framework of the One Health approach has increased the need for alternatives capable of helping with disease management while avoiding the onset of antimicrobial resistance phenomena. Antimicrobial peptides, which have a broad spectrum of action against pathogens, are a promising solution. Methods: In this work, we investigated the capability of three peptides (Trematocine, Chionodracine, and Cnd-m3) isolated from Antarctic fish to target bacterial and viral pathogens affecting aquaculture. Successively, we investigated their cytotoxicity versus a continuous embryonic cell line (DLEC) derived from European sea bass and their haemolytic activity against fish erythrocytes. Moreover, we evaluated their immunomodulatory effect. Results: Regarding antibacterial properties, Cnd-m3 was identified as the best peptide, demonstrating good bactericidal and bacteriostatic activity against various bacterial strains, including Lactococcus garvieae. Concerning this bacterium, ANS permeability assays showed that the Cnd-m3 peptide has a great ability to interact with its outer membrane, while TEM analysis revealed that the peptide, after destabilization of the cell membrane, interacts with nucleic structures. Considering the antiviral activity, Trematocine was effective against two tested pathogenic enveloped viruses. Moreover, the toxicity of Trematocine and Cnd-m3 was evaluated by investigating their cytotoxicity against a cell line derived from Dicentrarchus labrax and haemolysis against sea bass erythrocytes. Both revealed good selectivity towards pathogens at the lowest concentration. Finally, Cnd-m3 manifested light in vitro immunomodulatory properties. Conclusions: Overall, these data provide a solid basis for future studies assessing the potential applications of two of the tested peptides in aquaculture. Full article

Probiotic yeasts are increasingly proposed as adjuncts in fermented dairy products, but their behavior in kefir is still poorly described. This proof-of-concept study examined the effect of Saccharomyces boulardii CNCM I-745 supplementation on kefir produced with two traditional grain cultures and two industrial direct-vat-inoculation cultures during 21 days of cold storage at 4 °C. Microbiological, physicochemical, and sensory parameters were monitored on days 1, 7, 14, and 21. The starter culture type was the main source of variation, with traditional grain kefirs showing higher microbial counts and better sensory scores than industrial cultures. S. boulardii did not change pH, titratable acidity, Lactococcus spp., or total mesophilic aerobic bacteria, indicating that it can be added without disturbing the established kefir microbiota or its acidification pattern. The probiotic yeast increased the total yeast count, slightly modulated Lactobacillus spp., and gave a small improvement in taste–aroma scores. In the yeast-free industrial culture, S. boulardii maintained viable counts above 6 log CFU/g throughout storage, showing that it can act as the sole yeast source in kefir matrices that lack indigenous yeast. Traditional grain kefirs kept a more stable overall sensory quality across 21 days than industrial cultures. The multivariate analysis confirmed two largely independent quality dimensions, one related to lactic acid bacteria and acidity and another to sensory perception. The study supports the use of S. boulardii as a probiotic adjunct in kefir and provides preliminary effect-size information for future, adequately replicated trials. Full article

The aroma of camel milk is a key sensory indicator for evaluating its quality and flavor. Camel milk collected at different lactation stages exhibits unique flavor characteristics. However, no systematic study has yet explored the aroma characteristics and variation patterns of camel milk across these stages. This study employs HS-SPME-GC-MS, multivariate statistical analysis, and metagenomics to systematically reveal differences in aroma formation in camel milk across lactation periods and their interactions with microbial communities. A total of 577 metabolites is detected. Through OPLS-DA screening, 24 key differential flavor compounds are identified. ROAV analysis indicates that 2,4-undecadienal and (E)-2-undecenal are the main contributors to the fatty, creamy, fresh green, and citrus aromas of camel milk. Some compounds are more abundant in colostrum, while others are richer in mature milk. For microbiota, colostrum is dominated by Proteobacteria, Psychrobacter, and Janthinobacterium, whereas mature milk is dominated by Acinetobacter and Moraxella. Mature milk shows significantly higher alpha diversity and species richness. Spearman correlation analysis shows that core bacterial groups such as Enterococcus and Lactococcus are significantly positively correlated with characteristic flavor compounds, including aldehydes and lactones. This finding suggests that HS-SPME-GC-MS, combined with multivariate analysis, effectively distinguishes patterns associated with microbes and flavor metabolites in camel milk at different lactation stages, which provides a theoretical basis for quality control and further processing of camel milk. Full article

Lactococcosis has emerged as an economically and ecologically significant disease in aquatic animals worldwide. This study employed multilocus sequence typing (MLST) to investigate the genetic diversity of Lactococcus spp. strains from Brazilian fish species and evaluate their phylogenetic relationships with global isolates to elucidate potential epidemiological connections involving multiple host species and distinct geographic regions. A total of 55 isolates from different laboratories had their DNA extracted, followed by the amplification and sequencing of the internal fragments of seven housekeeping genes (als, atpA, tuf, gapC, gyrB, rpoC and galP). Sequence types (STs) and clonal complexes (CCs) were defined. An unrooted neighbor-joining phylogenetic tree was generated using allele profiles from this study and those previously reported from other aquatic animal species. The isolates comprised 29 STs (11 previously reported, 18 novel ones), which were grouped into species-specific CCs: CC5 (L. formosensis); CC4, CC17, CC62 (L. garvieae); CC24, CC29, CC97 (L. petauri). Considerable genetic divergence was observed, with L. formosensis and L. garvieae forming heterogeneous populations, while L. petauri was more homogeneous. These findings describe the MLST structure of the sampled isolates and should be interpreted as hypothesis-generating rather than population-level estimates of genotype prevalence. Phylogenetics confirmed groupings within the CCs and revealed additional phylogenetic clustering patterns. In conclusion, the Brazilian Lactococcus spp. strains analyzed in this study constitute a genetically diverse population based on their STs. MLST and phylogenetic analysis demonstrated genetic relatedness between the L. garvieae and L. formosensis isolates from this study and those from other aquatic animal species. In contrast, all the STs identified for L. petauri in this study were unrelated to the MLST lineages responsible for outbreaks in Brazilian Nile tilapia (Oreochromis niloticus) and North American rainbow trout (Oncorhynchus mykiss). This suggests that piscine L. petauri populations in the Americas evolved from distinct ancestral origins. Full article

Green tea is highly popular due to its richness in polyphenols exhibiting broad bioactivities. Tea polyphenols, primarily catechins and flavonoids, demonstrate health benefits following biotransformation by the gut microbiota to overcome limited bioavailability. However, metabolites and interaction between green tea polyphenol and the gut microbiota remains to be fully elucidated. This study investigates the biotransformation of metabolites and interaction between human gut microbiota (HGM) and green tea extract (GTE) through in vitro anaerobic fermentation. Temporal bioactivity assessments demonstrated that fermentation-enhanced antioxidant capacity and inhibition potential of α-glucosidase, α-amylase and pancreatic lipase peak at 6 h, showing strong correlations with polyphenol and flavonoid biotransformation kinetics. Using the untargeted metabolomics approach, 55 characteristic differential compounds during the fermentation process in GTE were characterized, including 15 catechins, 29 flavonoids, five organic acids and six other phytochemicals. Furthermore, nine microbial-transformed metabolites derived from GTE flavonoids were identified and the corresponding metabolic pathways were proposed simultaneously. Analysis of 16S rRNA gene sequencing revealed that GTE significantly enhanced gut microbiota diversity and induced structural reorganization, specifically enriching genera such as Bacteroides, Bifidobacterium, Lactococcus and Enterococcus, which are likely involved in flavonoid biotransformation of GTE. Thus, the findings provide new insights for elucidating microbiota-mediated metabolites of green tea polyphenol, and their bidirectional interactions in the human gut. Full article

The growing problem of antibiotic resistance poses one of the greatest threats to modern medicine, making the search for new, alternative strategies to treat bacterial infections a matter of priority. The aim of the study was to evaluate the antimicrobial activity of selected postbiotic substances (PS) and nisin against methicillin-susceptible (MS) and methicillin-resistant (MR) strains of coagulase-negative staphylococci (NAS) and mammaliicocci. The study was conducted on 24 strains of coagulase-negative staphylococci and mammaliicocci isolated from milk collected from Holstein-Friesian (HF) cows with subclinical mastitis. In vitro, PS/EMo (100–400 AU/mL) and PS/Eas (100–200 AU/mL) were the most effective, inhibiting the growth of all MS and MR strains of NAS and Mammaliicoccus spp. (100.0%). A high percentage of strains were also sensitive to postbiotic substances produced by Lactococcus lactis subsp. lactis PS/MK2/8 (400–1600 AU/mL), PS/MK1/3 (100–400 AU/mL), and nisin (100–25,600 AU/mL), both in MR strains (94.1%, 82.4%, 88.2%, respectively) and in MS strains (100.0%, 85.7% and 100%, respectively). PS/Esach (100–25,600 AU/mL) inhibited the growth of all strains, including the mecA gene-positive mammaliicocci strains (100.0%), but was slightly less effective against the MS strains (64.7%). The lowest activity was observed with postbiotic substances produced by Enterococcus faecium, PS/4231 (100–1600 AU/mL) and PS/9296 (100–6400 AU/mL), which inhibited the growth of 3 out of 17 MR strains (17.65%). Among the Mammaliicoccus strains with the mecA gene, postbiotic substances derived from strains PS/4231 and PS/9296 inhibited the growth of 42.9% and 28.6% of the strains, respectively. Four tested strains were sensitive to all postbiotic substances (MSC9, MSC11, MSC12 and SCH3). This study confirms that postbiotic substances and nisin inhibit the growth of staphylococci isolated from the milk of cows with subclinical mastitis, including methicillin-resistant strains. Full article

The rising health threat to healthcare workers (HCWs) demands innovative preventive solutions that are affordable, scalable, and easy to deploy, especially in resource-limited settings. This present study investigated the effects of Lactococcus lactis strain Plasma (LC-Plasma) intake on upper respiratory infection (URI)-like symptoms in a healthy healthcare-associated population in Vietnam. A randomized, placebo-controlled, double-blind, parallel-group clinical trial was conducted, integrating clinical symptom analysis with ex vivo immune response analysis of peripheral blood mononuclear cells (PBMCs). The study found that after 4 weeks of continuous oral LC-Plasma intake, participants in the LC-Plasma group had significantly fewer cumulative days of fever and fatigue than those in the Control group. Increased expression of interferon-stimulated genes (ISGs), particularly MxA, was observed in PBMC cultures from the LC-Plasma intake group. In PBMCs from LC-Plasma recipients classified as low IFN-α responders, the addition of CpG ODN 2216, a mild TLR9 agonist, significantly enhanced interferon-α production. Humoral factors derived from LC-Plasma-primed PBMCs demonstrated inhibitory effects on dengue virus replication in Huh-7 cells. These results suggest that LC-Plasma consumption by the healthcare-associated population reduces the severity of viral infection symptoms, notably fever and fatigue. Elevation of systemic antiviral immunity through activation of plasmacytoid dendritic cells (pDCs) to produce IFN-α and upregulation of ISG expression could be the mechanisms of action. Lactococcus lactis LC-Plasma supplementation, hence, presents a promising adjunctive approach to alleviate the burden of URI-like symptoms in low-resourced vulnerable populations. Full article