Characterization of a Newly Isolated Probiotic Strain from Oecophylla smaragdina, an Edible Insect Popular Among the Indigenous Communities of Northeast India.

Northeast India is amongst the 34 Biodiversity Hot Spots of the world with large number of unexplored flora and fauna. A total of 74 potential isolates with probiotic properties were isolated from Oecophylla smaragdina, an edible insect used by local tribes as a nutritious medicinal food source out of which, the most potential probiotic candidate was identified as Bacillus sp. PD6 by 16S rRNA sequencing. Cell surface trait analysis shows hydrophobicity and auto-aggregation percentage of 46.2 ± 0.32% and 61.41 ± 0.28% respectively. The cell free extract (CFE) of the isolate shows the presence of essential amino acids viz, lysine, valine, leucine, isoleucine, and threonine indicating its nutritional value. It survives significantly at pH range from 1 to 10 and capable of hydrolyzing bile salt. The CFE shows antagonistic effect against B. cereus ATCC 11778, E. coli ATCC 25922 and L. monocytogenes ATCC BAA751. FTIR spectra of bacterial exo-polysaccharide shows the presence of νC=C-H stretch, νN-H stretch, νC-H stretch, νC-H bending and νC=O stretch bonds. It was found to be non-cytotoxic against primary mouse liver cell line and sheep erythrocytes and also, sensitive against wide range of broad and narrow spectrum antibiotics making it recommendable for human consumption.