ISOLATION AND CHARACTERIZATION OF POTENTIAL PROBIOTICS FROM FERMENTED RAGI (ELEUSINE CORACANA)

Abstract

Objective: The aim of this study was to isolate, characterize and identify the potential lactic acid bacteria from fermented ragi millet (Eleusine coracana).Methods: A total of 177 isolates were isolated from the fermented ragi porridge. All the isolates were subjected to preliminary screening (Gram staining and catalase test). The physiological features of the probiotic isolates such as tolerance to pH (2.0, 4.0), phenol (0.3%, 0.5%) and bile salt (0.3%) were carried out. Antibiotic susceptibility test was performed using disc diffusion method. Free radical scavenging assay was conducted by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The isolates were further characterized for their cholesterol-lowering property. Based on their survival ability and biochemical tests, the selected potent isolates were identified by 16S rRNA gene sequence by PCR and phylogenetic analysis. The 16S rRNA gene sequencing confirmed that isolates were Lactococcus lactis RS01, Lactobacillus plantarum RS09, Lactobacillus plantarum RS16 and Lactobacillus plantarum RS23.Results: Twenty five isolates were screened from the 177 total isolates based on their morphological and biochemical characteristics (Gram staining and catalase test). All the isolates showed tolerance against acid, phenol and bile salts. However, RS09 and RS23 exhibited maximum viable count and demonstrated good tolerance at the end of 3 h. Highest antioxidant activity was recorded in RS09 ranging from 32-85%. Among the tested strains, the degradation rate of supernatants, RS09 (61.9%), RS23 (60%) and RS01 (58.97%) and RS16 (56.2%) showed the highest cholesterol assimilation rate. In addition, they also found to be resistant and sensitive to few antibiotics.Conclusion: Based on the obtained results, these isolates are ideal in vitro probiotic strains and can be used further for in vivo evaluation.