RESUMO
BACKGROUND: Neonatal feces are one of the most important sources for probiotic isolation. The purpose of this study was the isolation and identification of Bifidobacterium spp. from neonatal feces and the evaluation of in vitro probiotic properties of strains including safety tests. RESULTS: A total of 40 isolates were obtained from 14 healthy newborns' feces in Erzurum province, Türkiye. By their rep-PCR patterns and 16S rRNA gene sequences, isolates were identified as 26 Bifidobacterium breve and 14 Bifidobacterium longum. Fifteen of the isolates tolerated bile salts and showed high resistance to simulated gastric juice. Isolates exhibited varying rates of auto-aggregation and hydrophobicity. In addition, most of the isolates displayed antibacterial activity against Escherichia coli O157:H7, Staphylococcus aureus ATCC 29213, Salmonella Typhimurium RSHMB 95091, and Pseudomonas aeruginosa ATCC 9027. However, only one strain showed bile salt hydrolase activity and two strains showed the ability to produce H2O2. Bifidobacterium strains were generally sensitive to the tested antibiotics and lacked kanamycin, gentamicin, and streptomycin resistance genes, and hemolytic and DNAse activities. On the other hand, it was determined that five strains had various virulence genes including gelE, esp, efaAfs, hyl, and ace. CONCLUSION: Results of the present study suggested that B. longum BH28, B. breve BH4 and B. breve BH5 strains have the potential as probiotic candidates for further studies. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Assuntos
Bifidobacterium , Probióticos , Recém-Nascido , Humanos , RNA Ribossômico 16S/genética , Peróxido de Hidrogênio , Turquia , Fezes/microbiologia , Antibacterianos/farmacologiaRESUMO
Microgreens can be contaminated by various preharvest sources including soilless substrate, plant nutrition solution, water and seeds. The aim of this study was to determine the transfer level of Salmonella, Shiga toxin-producing Escherichia coli O157:H7, and Listeria monocytogenes to the edible part of various type of microgreens from plant nutrient solution-soaked perlite as soilless substrate or seeds. Ampicillin resistant 3-strain cocktails of Salmonella and E. coli O157:H7 and non-resistant L. monocytogenes were independently inoculated into plant nutrient solution-soaked perlite and seeds in low (102-103 CFU/g) and high (105-106 CFU/g) populations. Twenty types of microgreens were grown in inoculated perlite. The seed inoculation was performed on five types of microgreens. Correlations between pathogen transfer levels with seed characteristics and harvest time were assessed. Pathogen populations (1.6 ± 0.2 to 7.7 ± 0.1 log CFU/g) transferred to microgreens were dependent on type of pathogen and microgreen but not affected by contamination source and inoculation level. The level of pathogen transferred to microgreens had a moderate to high negative correlations (R2) with seed surface area (-0.551 to -0.781), seed weight (-0.735 to -0.818), and harvest time (-0.332 to -0.919) when grown in Salmonella and E. coli O157:H7 inoculated perlite. This study suggests a high risk of pathogen population transferring to microgreens in case of seed or soilless substrate contamination when pathogen growth or survival is supported in plant nutrient solution.
Assuntos
Óxido de Alumínio , Escherichia coli O157 , Listeria monocytogenes , Dióxido de Silício , Microbiologia de Alimentos , Contagem de Colônia Microbiana , Salmonella , SementesRESUMO
The aim of this study was to evaluate the impacts of enzymatically synthesized α-glucans possessing α-1,4- and α-1,6-glucose linkages, and varying in branching ratio, on colonic microbiota composition and metabolic function. Four different α-glucans varying in branching ratio were synthesized by amylosucrase from Neisseria polysaccharea and glycogen branching enzyme from Rhodothermus obamensis. The branching ratios were found to range from 0 % to 2.8 % using GC/MS. In vitro fecal fermentation analyses (n = 8) revealed that the branching ratio dictates the short-chain fatty acid (SCFA) generation by fecal microbiota. Specifically, slightly branched (0.49 %) α-glucan resulted in generation of significantly (P < 0.05) higher amounts of propionate, compared to more-branched counterparts. In addition, the amount of butyrate generated from this α-glucan was statistically (P > 0.05) indistinguishable than those observed in resistant starches. 16S rRNA sequencing revealed that enzymatically synthesized α-glucans stimulated Lachnospiraceae and Ruminococcus related OTUs. Overall, the results demonstrated metabolic function of colonic microbiota can be manipulated by altering the branching ratio of enzymatically synthesized α-glucans, providing insights into specific structure-function relationships between dietary fibers and the colonic microbiome. Furthermore, the slightly branched α-glucans could be used as functional carbohydrates to stimulate the beneficial microbiota and SCFAs in the colon.