Preliminary Selection Criteria for Biottherapeutic Potentials of Indigenous Probiotic Candidates in the Control of Children Diabetes Mellitus

Background: In addition to nutritional benefits, African traditional fermented foods and beverages serve as popular sources of natural and modified probiotics in human health. However, therapeutic potential of probiotic for human diabetic control is yet to be fully investigated locally.

Method: Lactobacillus strains were isolated from Nigerian indigenous fermented foods and beverages (burukutu, fufu, kunun zarki, nono, otika, pito, ogi, otika, sekete, wara and wuya), and identified using standard phenotypic taxonomic tools. Effect of different carbon sources on the growth of the four potential probiotic candidates was determined in modified-MRS medium. Production of lactic acid from glucose by the LAB was determined, using quantitative assay. Relative ability of the Lactobacillus strains to survive lethal acidic conditions was investigated in vitro by a simulated method of exposing the Lactobacillus strains to different pH, using HCl and HCl-modified MRS broth.

Results: A total of 254 Lactobacillus strains were isolated from Nigerian indigenous fermented foods and beverages. Distribution and frequency of occurrence indicated the most-recovered Lactobacillus species to be Lb. acidophilus (fufu), Lb. brevis and Lb. delbrueckii (otika, pito, sekete and wuya), Lb. brevis (kunun zarki), Lb. delbrueckii (burukutu), Lb. bulgaricus (nono), and Lb. plantarum (ogi and wara). All the Lactobacillus strains fermented glucose; however L. bifidus, L. brevis, and L. leichmanii strongly fermented glucose. Determination of effect of various carbon sources (2%) on the growth of the potential probiotic strains in modified MRS medium was generally in the decreasing order, glucose > sucrose > fructose > maltose > sorbose > lactose > galactose > mannitol. Comparative nutritional studies of the Lactobacillus strains, based on modified medium composition indicated glucose as the most essential nutrient, with maximum growth (log 3.31 - 3.42 cfu ml-1). All the potential probiotic Lactobacillus strains produced varying increasing amounts of lactic acid in MRS medium between 12h and 72h, followed by a general decline towards 96h of incubation Selected potential probiotic strains in modified MRS medium survived between pH5 (log 2.97-3.23 cfu ml-1) and pH13 (log 3.01-3.28 cfu ml-1), and were tolerant to 0.1-2.5% physiological bile salts. There was no growth/survival of the Lactobacillus strains at 24h in pH 1 and pH 3 but there were growths at pH 3 in MRS and MRS-basal medium between 2 and 12 hours of incubation, although more growth, in form of colony forming units were obtained from the MRS-modified basal medium than in the MRS-modified medium.

Conclusion: Selected indigenous probiotic Lactobacillus candidates from Nigerian fermented foods and beverages possessed certain specific health benefits, based on their preliminary metabolic and physiological potentials, which can be simulated to improve health status of diabetic patients, by conferring low sugar level due to natural glucose utilisation by the probiotic Lactobacillus candidates.