Molecular and Probiotic Characterizations of <i>Lactobacillus reuteri</i> DSM 12246 and Impact of pH on Biomass and Metabolic Profile in Batch-Culture

Abstract

Lactobacillus reuteri is a powerful probiotic and adjunct functional culture candidate received a lot of scientific attention as it is one of the few endogenous “Lactobacillus” species found in the gastrointestinal tract of vertebrates, including humans, rats, pigs and chicken. The organism has been widely utilized as a probiotic in humans and animals for many years. In the present work L. reuteri DSM 12243; a high reuteri producer strain was molecularly characterized by 16SrRNA and RAPD analyses further, the probiotic properties including acid resistance, bile tolerance, adhesion to epithelial gastric cells, and antibiotic susceptibility were also assessed. Furthermore, the effect of pH on biomass production and metabolic profile of L. reuteri DSM 12246 in batch-culture was studied. The L. reuteri DSM 12246 showed a high similarity with L. reuteri strain I49 KR 36477 (100%) and type strain ATCC 55730 (99% of identity). The strain adhered well to CaCO2 cells and showed to be a highly resistance to acid juice (pH 3.0), with 0.7 log10 cfu/ml reduction in count after 60 min exposition. There is no significant change in the cell count after exposure to bile salts. In batch-cultures, at low pH values both glucose consumption and metabolites were low while the production of lactic acid was noticeable. Maximum biomass was reached at pH 5.5, with growth rate of μ = 0.641/h. The switch in pH values from 3.7 to 6.7 resulted in raising of glucose depletion as well as in the yield of acetate and ethanol. It is concluded that L. reuteri DSM 12246 was deemed as a successful candidate to be used as potential probiotic.