This study examined antimicrobial resistance (AMR) in Streptococcus thermophilus and Lactobacillus spp. isolated from traditional Indian Dahi. From 96 traditional Dahi samples, 104 S. thermophilus and 100 Lactobacillus isolates were tested for antibiotic susceptibility. S. thermophilus showed predominant resistance to nalidixic acid and oxacillin, with additional resistance to clindamycin, trimethoprim, ofloxacin, co-trimoxazole, erythromycin, cefuroxime, and cefepime. Lactobacillus isolates were highly resistant to nalidixic acid (97%), norfloxacin, and ofloxacin, followed by trimethoprim, co-trimoxazole, teicoplanin, oxacillin, amikacin, and vancomycin. Multiple antibiotic resistance index ranged from 0.07-0.38 in S. thermophilus and 0.07-0.45 in Lactobacillus. Thirteen S. thermophilus isolates were extended-spectrum beta-lactamase producers harboring blaTEM, with high MIC cutoffs against cefepime and cefotaxime. Macrolide resistance genes were found in S. thermophilus, aminoglycoside resistance genes in Lactobacillus, and the multidrug transporter gene (emeA) in 16 S. thermophilus strains. No mobile genetic elements were detected. These findings highlight AMR in traditional fermented milk bacteria, underscoring food-chain risks.
Hepatocyte-specific Yap1 knockout mice more susceptible to liver inflammation. This study investigated the effect of Lycium barbarum (wolfberry) on the bacterial community structure of knockout mice and its role as a potential prebiotic candidate. Mice with hepatocyte-specific Yap1 knockout exhibited a reduction in A. muciniphila colonization. Wolfberry augmented the relative abundance of Verrucomicrobia as determined by 16S rRNA analysis. Moreover, wolfberry enhanced the composition of the intestinal microbiota in mice and boosted the relative abundance of Akkermansia, Alistipes_A, and Odoribacter. Interestingly, Yap1 knockout mice during wolfberry intervention did not affect the tight connection of the intestine in mice. Nevertheless, wolfberry did not decrease the levels of aspartate transaminase (AST), alanine transaminase (ALT), and total bile acid (TBA) in mice. Therefore, short-term intervention with wolfberry did not improve liver damage in knockout mice.
Mam is a naturally fermented aquatic product from Vietnam that contains diverse lactic acid bacteria (LAB) communities. This study characterized and selected proteolytic LAB with probiotic potential isolated from four Mam sources. Among the 42 isolates, 26 were LAB, and 17 exhibited proteolytic activity (2.69-19.63 U/mg), classified into low, medium, and high groups using K-means clustering. Four promising proteolytic LABs were identified: Lactiplantibacillus pentosus S02, Lp. plantarum S12, Lp. plantarum T06, and Companilactobacillus futsaii T21. They were non-hemolytic and showed no irregular antibiotic resistance. Lp. plantarum T06 demonstrated the best bile salt tolerance (52.22% survival after 3 h), whereas Lp. plantarum S12 exhibited the best antibacterial activity against Bacillus cereus (25.07 mm). They inhibited even Gram-negative pathogens. Overall, the selected proteolytic LAB, highlighted as Lp. plantarum T06, exhibited desirable safety and probiotic properties, suggesting their potential as probiotic starters or for bioactive compound production after more in-depth safety evaluations.
Gray mold presents a significant threat to the postharvest preservation of fruits. Trehalose can inhibit the growth and reproduction of pathogenic fungi while enhancing the disease resistance of postharvest fruits. In this study, treatment with trehalose resulted in a significant reduction in the disease index, fruit rot rate, and weight loss rate. Through comparative omics analyses, we identified 2201 differentially expressed genes (DEGs) and 383 differentially expressed metabolites (DEMs). Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed that most DEGs were involved in plant hormone signal transduction, amino acid biosynthesis, and ABC transporters pathways. Additionally, genes related to defense mechanisms and their biosynthetic pathways exhibited higher expression levels. These findings suggest that trehalose can induce the expression of endogenous disease resistance signaling pathways in fruits, thereby enhancing their resistance to gray mold.
This study aimed to isolate and characterize collagenolytic bacteria from marine sediment using fish waste as a substrate. Collagenase-producing bacteria were obtained by serial dilution (up to 10(-6)) and spread plate methods. Among 15 isolates, one strain showed the highest collagen degradation activity, indicating strong potential for fish by-product utilization. Cultural, morphological, and 16S rRNA analyses identified the isolate as Bacillus subtilis. The 16S rRNA gene was sequenced and deposited in GenBank as Bacillus subtilis dfs3 (accession JF713459.1). Collagenase activity was confirmed by clear zones of collagen hydrolysis, and the enzyme was purified using ammonium sulfate precipitation and DEAE cellulose chromatography, achieving similar to 11-fold purification with an activity of 7200 units/mg. The purified enzyme had a molecular mass of 45 kDa. Optimal activity occurred at pH 8.0 and 60 degrees C, with good stability across pH 7.5-8.5 and 20-55 degrees C. These results demonstrate a sustainable and efficient approach for collagenase production with strong industrial potential.
Exopolysaccharides (EPS) from lactic acid bacteria are biological macromolecules with significant biological activities, including functioning as prebiotics to promote the growth of probiotics. This study isolated four lactic acid bacterial strains from kimchi and kefir, namely Lactiplantibacillus plantarum (Lac_KC), Pediococcus acidilactici (Ped_KC), Leuconostoc lactis (Leu_KF), and Weissella cibaria (Wei_KF). Ped_KC and Wei_KF exhibited good abilities to auto-aggregate and co-aggregate with E. coli. Meanwhile, Ped_KC and Lac_KC were more tolerant to simulated gastric and intestinal conditions, while the other two strains exhibited significantly lower survivability under gastric conditions. Regarding the EPS produced from these four strains, the results showed that the recovery from Leu_KF was highest (7.64 g/l). SEM also showed that EPS from Leu_KF had a distinct structure, while FT-IR and XRD showed similarities in their functional groups and amorphous structure. When using EPS as prebiotics, Ped_KC and Leu_KF showed the strongest growth-promoting ability upon EPS addition level of 0.1%.
Growing health-enhancing awareness has promoted the inclusion of fermented foods in daily diets. In this study, 850 yeasts were isolated from yak dahi and chhurpi, out of which only 15 were further screened. These isolates were identified as Yarrowia lipolytica (5), Saccharomyces cerevisiae (4), Kluyveromyces lactis (2), Kluyveromyces marxianus (1), Wickerhamomyces anomalus (1), Candida parapsilosis (1), and Candida metapsilosis (1). These isolates exhibited probiotic traits and showed no safety concern based on in-vitro safety evaluation. Further, these isolates have demonstrated cholesterol-lowering activity, antioxidant activity, anti-inflammatory activity, and antidiabetic activity relevant functional attributes. PCA biplot analysis obtained from the variance-covariance matrix at a 10k bootstrap value indicated Saccharomyces cerevisiae DUAY-53 from yak dahi and Kluyveromyces lactis CUBY-19 from yak chhurpi have the highest potential as probiotic yeast. The findings highlight fermented yak milk as a valuable reservoir of safe and robust probiotic yeasts, suitable for use in functional food development.
