Abstract:
Probiotics are living microorganisms which can change the microbiota of the host and
ultimately have beneficial effects on the health of the host when present in significant
numbers. Their applications are very diverse as they are used in foods, for the treatment
and prevention of many diseases, maintaining the health of an individual and currently
their applications as therapeutics are being discovered. The aim of my study was to
isolate potential probiotics from indigenous sources, evaluate their characteristics and
perform their safety assessment. Different varieties of indigenous rice were taken as
source for the isolation of bacteria. Identification of the isolated strains was performed
by various biochemical tests and 16S rRNA sequencing. The safety of isolated strains
was assessed on wistar rats for 10 weeks including survival, adhesion, and colonization
of the strains in gastrointestinal tract of rats. Antibacterial activity of isolated strains
against five pathogenic strains namely Shiga toxin producing Escherichia coli,
Enterococcus faecalis, Salmonella enterica, Pseudomonas aeruginosa and Klebsiella
Pneumoniae was performed by well diffusion assay. Three strains were isolated whose
biochemical testing and sequencing results revealed they were Enterococcus faecium.
No significant antagonism was seen against K. Pneumoniae and P. aeruginosa whereas
significant results were obtained against STEC, E. faecalis and S. enterica. Strains
survived the GIT tract as they were re-isolated as rifampicin resistant colonies in the
fecal samples of rats. They were able to adhere and colonize small intestine; large
intestine and caecum of rats. The rats were gaining weight and no symptoms of disease
were shown ensuring the safety of the strains. The results of the study suggest that these
E. faecium strains can be used as potential probiotic strains.
