Probiotic characterization of indigenous Bacillus velezensis strain DU14 isolated from Apong, a traditionally fermented rice beer of Assam

Study was carried out to isolate and characterize novel indigenous probiotic candidates from traditionally prepared rice beer locally known as Apong in Assam, India. The most potential Probiotic candidate was identified as Bacillus velezensis strain DU14 (GenBank accession no. MK177191) on the basis of 16S rDNA gene sequencing. It was found to show significant tolerance in a pH range of 2-9 and survived in presence of 1% (w/v) of bile salt. It showed sensitivity against both broad and narrow spectrum antibiotics with antagonistic activities against both Gram positive (Bacillus cereus ATCC-11778) and negative and (Escherichia coli ATCC-25922) pathogens. The isolate was found non haemolytic in nature and the cell-free supernatant concentrate (CFSC) of the isolate showed no cytotoxicity against mouse liver cells. The FTIR analysis of exopolysaccharide synthesized by the isolate showed the presence of upsilon(C=C-H stretch), upsilon-(C=C stretch), upsilon(CH2) (symmetrical stretch), upsilon(C-H bend), and upsilon(C-O stretch).