Isolation, identification and optimization of exopolysaccharide-based bioflocculant synthesis by soil bacteria Bacillus atrophaeus NR-12

Bioflocculants are polysaccharide-based, biodegradable macromolecules synthesized by soil microorganisms. A bacterium prodicing an extracellular bioflocculant wasisolated from the salty and dry soil and identified as Bacillus atrophaeus. Effects of culture conditions including carbon sources, nitrogen sources, pH, shaker speed on bioflocculant production were studied. Isolate comparative analysis of 16S rRNA sequence identified the isolate to have 99% similarity to Bacillus atrophaeus and it was deposited in the GenBank as Bacillus atrophaeus NR- 2 with accession number OP679007. The strain was characterized by ability to grow and synthesize the bioflocculant in alkaline conditions – pH 11. It was supposed that the strain can overcome adverse effects of environment – alkalinity and salinity by enhanced production of bioflocculant in stress. In the optimized medium (sucrose and tryptone used as C/N sources) the strain produced 4.76 mL bioflocculant.