Isolation and characterization of Lacticaseibacillus casei RIGLD MG-۱ from the gastric microbiome of a healthy human subject

BACKGROUND AND OBJECTIVEProbiotics are beneficial organisms that have been extensively studied for their positive effects on human health. Lactobacillus bacteria are one of the most frequently consumed probiotic species and can colonize various niches in the human gastrointestinal tract. This study aimed to isolate and characterize Lactobacillus strains from the gastric microbiome of healthy human subjects.MATERIALS AND METHODSStomach biopsies were obtained from healthy individuals undergoing routine endoscopic procedures at Taleghani Hospital in Tehran. The collected samples were incubated in selective De Man, Rogosa and Sharpe agar (MRS) under anaerobic conditions. Isolated colonies were then identified using colony morphology, and Gram staining, followed by PCR and ۱۶S rRNA gene sequencing. The isolated Lactobacillus strains were further characterized for their safety, functional properties, and antibiotic susceptibility testing using disk diffusion method.RESULTS AND DISCUSSIONWe successfully isolated and identified a strain of L. casei RIGLD MG-۱ from the gastric biopsies of a healthy human. The strain exhibited no hemolytic, gelatinase, and DNase activities and high tolerance towards acid and bile salts. Furthermore, this strain was sensitive to ampicillin, erythromycin, clindamycin, tetracycline, and chloramphenicol and resistant to vancomycin, kanamycin, streptomycin, and nalidixic acid.CONCLUSIONIn conclusion, our results demonstrated that the isolated L. casei RIGLD MG-۱ was safe and tolerant to harsh gastric environment, and potentially could be considered as a probiotic strain. Further research is required to assess the antimicrobial and immunomodulatory activity and beneficial effects of this strain on stomach-related diseases and Helicobacter pylori infection.

کلیدواژه ها:

Gastric microbiome ، Probiotic ، Lactobacillus ، Isolation ، Safety assessment