“Production and Evaluation of Probiotic Lactic Acid Bacteria (LAB) for Therapeutic Application

The thesis reports isolation, identification and characterization of probiotic lactic acid
bacteria from healthy breast fed infants fecal matter and studies on the beneficial effects
in vitro and in vivo models. The isolates were evaluated for potent probiotic properties by
carrying out a number of in vitro studies. The selected isolates were characterized by
phenotypic and genotypic methods. Out of 22 isolates two were selected as potent
probiotic strains based on their in vitro performances. Both the selected isolates were
identified as Lactobacillus fermentum. The isolates were designated as CFR 2195 and
2196. Lactobacillus fermentum CFR 2195 was selected for the further studies. Functional
properties such as production of amino acids, vitamin B12, synbiotic antimicrobial effects
and adherence towards HT-29 and Caco-2 cell-lines were carried out. A medium was
designed with optimum physical and nutritional parameters for the efficient production of
biomass and lactic acid. Productive performance in the optimum point medium, was
closer to that of the MRS medium, however much cheaper when compared to MRS
medium. There was no significant change in the quantity of biomass obtained from the
optimized fermentation medium in comparison to that in MRS medium, while there was a
considerable decrease (27.20%) in the cost. Thus, it could be said that the medium
optimized in this study was not only economical but also favourable for the growth of L.
fermentum.
Probiotic L. fermentum CFR 2195 has shown anti-inflammatory activity in the intestines
of TNBS model of rat colitis. The colonization of the probiotic L. fermentum in the
colonic lumen resulted in positive effects, probably derived from their
immunomodulatory properties. The administration of the probiotic L. fermentum CFR
2195 facilitates the recovery of the inflamed tissue in the TNBS model of rat colitis, an
effect associated with amelioration of the production of some of the mediators involved
in the inflammatory response of the intestine. This beneficial effect could be ascribed to
its ability to prevent oxidative stress that occurs under inflammatory condition, through
the increased production of glutathione, which might attenuate the exacerbated immune
response evoked by the colonic instillation of the hapten TNBS in the rats.