Bacillus siamensis I7B strain as heavy metal quencher and probiotics; isolated from gut of Stolepherous commersonni

Probiotic products have been administered in food, medicine, dairy and fermentation industry to enhance the beneficial functions in the host. In the present study gut bacteria of stolepherous commersonnii have been isolated and subjected to screening for heavy metal resistance. A potent heavy metal resistant bacterial strain of gut microbiota was subjected to assessment for its probiotic and antioxidant potential. Four bacterial strains namely I7A, I7B, I7C, and I8 were isolated and the strain I7B showed heavy metal resistant potential (upto 20 mg/ml of Cr, Cr, and Pb). The strain I7B showed high sensitivity to Streptomycin (10 μg), low sensitivity to Rifampin (5 μg) and resistant to pencillin (2 μg, 10 μg). Atomic absorption spectrometry studies showed that the I7B strain possess maximum heavy metal (Cu) removal ability of 81.64 % in textile dye effluent and the strain was identified as Bacillus siamensis by 16S rRNA gene sequencing studies. Hence I7B strain was named as Bacillus siamensis I7B and has been submitted in NCBI with accession number MN404539. Bacillus siamensis 17B strain possess high acid tolerance (90.9 %), high bile tolerance (96.9 %) and nonhemolytic. The17B strain showed auto aggregation (28±0.011%) and coaggregation potential (27±0.16 %) which could be a feasible characteristic of potent probiotic strain. Cell free Supernatant of Bacillus siamensis I7B strain possess good DPPH free radical scavenging ability (59.43±0.002 %) and moderate hydroxyl radical scavenging ability (27.6±0.010 %). Biopreservation effect of Bacillus siamensis I7B strain on tomato puree showed 72 % growth inhibition against A. niger for 15 days.