The isolate showed promising probiotic characteristics, maintaining viability under acidic conditions (pH 2), bile salts, and phenol, and the absence of hemolytic activity and significant biofilm formation further supports its candidacy as a safe probiotic.
Overall, UzMU25 exhibited preliminary enzymatic, antagonistic, and biofilm-forming characteristics of biotechnological interest, but whole-genome antimicrobial-resistance screening and more comprehensive phenotypic and toxicological evaluations are required before the strain can be recommended for probiotic or other practical applications.
Luiza Tagayeva, K. Normurodova, S. Jabborov et al.· Microorganisms· 0 citations
Pediococcus pentosaceus (P. pentosaceus) is a ubiquitous lactic acid bacterium recognized for enhancing the sensory properties, dietary benefits, and safety of fermented foods. This study isolates and characterizes a Tibetan kefir-derived strain, P. pentosaceus K6, using integrated genomic and phenotypic approaches. Whole-genome sequencing and in vitro assays confirmed a favorable safety profile for K6, showing no hemolytic activity or harmful metabolite production, and lacking pathogenic virulence determinants, transferable antibiotic resistance genes, or functional plasmid conjugation elements. K6 showed strain-specific probiotic features, including 83.83% survival at pH 3.0 for 2 h, 71.16% survival under simulated gastrointestinal digestion, 89.30% auto-aggregation at 48 h, and strong inhibition against Listeria monocytogenes (29.83 ± 0.06 mm). Compared with previously reported P. pentosaceus strains, K6 uniquely combines gastrointestinal tolerance, adhesion-related traits, and anti-Listeria activity. The antiSMASH analysis identified putative type III polyketide synthase and terpene gene clusters, providing genetic candidates for this antimicrobial phenotype. Furthermore, specific carbohydrate-active enzymes and exopolysaccharide biosynthetic genes indicate strong potential for carbohydrate metabolism and food matrix adaptation. Collectively, these genomic and phenotypic findings support P. pentosaceus K6 as a highly promising candidate for probiotic and biopreservation applications.
Xiao Huang, Yingying Yang, Xinhe Zhang et al.· Frontiers in Microbiology· 0 citations
Traditional Thai natto is one source of Bacillus spp. Due to their spore-forming ability, Bacillus spp. are considered promising probiotic candidates capable of surviving harsh environmental condition. This study aimed to genetically identify and characterize Bacillus strains isolated from traditional Thai natto and evaluate their probiotic potential, including survival ability under various acidic pH levels, bile salt concentrations, and electrolyte monogastric system model (EMSM). Antibacterial activity and safety assessments including hemolytic activity and antibiotic susceptibility were also evaluated. More than 10 colonies were found in the samples. Only 3 isolates were selected based on Bacillus morphology. The isolates displayed biochemical features consistent with Bacillus and were identified with 16S rRNA sequencing, showing high sequence similarity to: B. subtilis CMI 7 (99.86%), B. subtilis CMI 9 (99.72%), and B. cereus CMI 10 (98.91%). All isolates exhibited key probiotic traits and showed statistically significant differences in survival rates under acidic pH (over 62.35±4.50% at 4 h; and over 51.61±5.08% at 24 h), bile salt concentrations (over 93.60±2.42% at 4 h; over 82.23±3.90% at 8 h; and over 39.65±3.02% at 24 h), and EMSM conditions (over 73.08±3.18% at 4 h). Isolates CMI 7 and CMI 9 exhibited antagonistic activity against S. aureus ATCC 9144 and strain DMST 2933 and E. coli ATCC 25923, demonstrating non-hemolytic and antibiotic-sensitive features. In contrast, isolate CMI 10 lacked antagonistic activity, exhibited β-hemolysis, and showed resistance to several antibiotics, representing a significant safety concern. This study suggests that B. subtilis CMI 7 and CMI 9 are probiotic candidates with safety profiles. Further study should be conducted to explore other biological properties of these Bacillus spp.
Vongsathorn Ngampuak, Natnicha Jumpadang, Thirayut Sombun et al.· Current Applied Science and...· 0 citations
Findings establish B. velezensis strains BP5 and BP103 as highly promising biocontrol agents, combining high genetic stability with diverse secondary metabolite profiles, suitable for development into sustainable microbial bio-bactericides.
Lê Uyển Thanh, Vu Nhat Tan, T. Huyen et al.· Frontiers in Microbiology· 0 citations
Background Probiotics are increasingly used in aquaculture to enhance fish survival, growth, and health, offering a sustainable approach to fish farming. Objective This study assessed the probiotic properties of Bacillus pumilus HFS2, isolated from the digestive tract of Heteropneustes fossilis. Method Among fourteen isolates, HFS2 was characterized using physiological, biochemical, and 16S rRNA analyses, and it's in vitro probiotic properties as well as in vivo safety were evaluated. Results The isolate was Gram-positive, rod-shaped, motile, and aerobic, showing positive results for methyl red, catalase and Voges–Proskauer tests, and a negative result for the indole test. It fermented dextrose, lactose, maltose, and mannitol with acid production but did not ferment sucrose. In vitro probiotic assessments showed that the strain tolerated a temperature range of 4–35 °C, survived at pH 2–5, and tolerated bile concentrations of 2.5–7.5%. The isolate demonstrated promising adhesion-related properties, including autoaggregation (66%), cell surface hydrophobicity (69% with xylene and 68% with toluene), and coaggregation with Lactococcus lactis (53%) and Staphylococcus arlettae (49%). It also exhibited inhibitory activity against fish pathogens such as Lactococcus garvieae, Aeromonas caviae, A. jandaei, A. veronii, and A. hydrophila. The isolate exhibited γ-hemolytic activity, strong biofilm-forming ability, and susceptibility to commonly used antibiotics, including ampicillin, vancomycin, erythromycin, tetracycline, chloramphenicol, and ciprofloxacin, while resistance observed only against cefotaxime. In vivo safety evaluation through intraperitoneal injection and immersion challenge at 108 CFU/mL indicated no pathogenic effects in H. fossilis. Conclusion These results suggest that B. pumilus HFS2 is a resilient and promising potential probiotic candidate for aquaculture applications.
Md. Sakhawat Hossain, Md Imtiaz Ahamed, Ashoka Paul Sudipta et al.· Journal of Genetic Engineeri...· 0 citations
Marine-derived probiotic bacteria have emerged as promising alternatives to antibiotics in sustainable aquaculture owing to their resilience, metabolic versatility, and ability to produce beneficial bioactive compounds. In the present study, the probiotic and functional potential of
Bacilllus subtilis
ULB16, a marine endophytic bacterium isolated from
Ulva lactuca
, was comprehensively evaluated. The safety assessment revealed susceptibility to several clinically relevant antibiotics, while no extracellular DNase activity was detected, supporting its non-virulent nature. The strain exhibited tolerance to gastrointestinal-like stress conditions, including acidic pH, bile salts, and simulated gastric juice, indicating its ability to survive gastrointestinal transit. Functional probiotic characterization demonstrated cell surface hydrophobicity, auto-aggregation, and co-aggregation with representative enteric pathogens (
Escherichia coli
,
Salmonella enterica
, and
Klebsiella pneumoniae
) as well as aquaculture-associated pathogens (
Aeromonas hydrophila
and
Vibrio parahaemolyticus
).
B. subtilis
ULB16 also exhibited biofilm-forming ability and showed higher adhesion to HT-29 intestinal epithelial cells than the commercial probiotic strain
Alkalihalobacillus clausii.
Notably, the isolate exhibited β-galactosidase activity of 0.0565 U/mL, a relatively uncommon feature among
Bacillus
-based probiotics, suggesting additional nutritional and functional benefits associated with lactose metabolism. Collectively, the findings demonstrate that
B. subtilis
ULB16 possesses a combination of desirable probiotic traits, including stress tolerance, pathogen interaction capability, epithelial adhesion, and functional enzyme activity. These multifunctional properties highlight its potential as a promising marine-derived probiotic candidate for sustainable biotechnological applications.
Swathy Sadanandan Anand, Sreetha Hely, B. G. Nair et al.· Frontiers in Marine Science· 0 citations
