Cellular fatty acid profile and H+-ATPase activity to assess acid tolerance of Bacillus sp. for potential probiotic functional attributes.

The present study has been focused widely on
comparative account of probiotic qualities of Bacillus spp.
for safer usage. Initially, 170 heat resistant flora were isolated
and selected for non-pathogenic cultures devoid of cytK,
hblD, and nhe1 virulence genes. Subsequently, through biochemical
tests along with 16S rRNA gene sequencing and
fatty acid profiling, the cultures were identified as Bacillus
megaterium (AR-S4), Bacillus subtilis (HR-S1), Bacillus
licheniformis (Csm1-1a and HN-S1), and Bacillus flexus
(CDM4-3c and CDM3-1). The selected cultures showed 70–
80 % survival under simulated gastrointestinal condition
which was also confirmed through H+-ATPase production.
The amount of H+-ATPase increased by more than 2-fold
when grown at pH 2 which support for the acid tolerance
ability of Bacillus isolates. The study also examined the
influence of acidic pH on cellular fatty acid composition of
Bacillus spp. A remarkable shift in the fatty acid profile was
observed at acidic pH through an increased amount of even
numbered fatty acid (C16 and C18) in comparison with odd
numbered (C15 and C17). Additionally, the cultures exhibited
various probiotic functional properties. Overall, the study
increases our understanding of Bacillus spp. and will allow
both industries and consumers to choose for well-defined
probiotic with possible health benefits.