Bioremediation potential of a halophilic Halobacillus sp. strain, EG1HP4QL: exopolysaccharide production, crude oil degradation, and heavy metal tolerance

A halophilic bacterial strain, EG1HP4QL, was isolated from a salt sample from Lake Qarun, Fayoum Province, Egypt. Morphological, physiological, biochemical, and phylogenetic analyses indicated that the strain belonged to the genus Halobacillus. Strain EG1HP4QL produced an extracellular polysaccharide (EPS), with production peaking (5.9 g L-1) during growth on medium S-G containing 2% (w/v) sucrose at 35 degrees C (pH 8.0). The EPS had significant emulsifying activity (E-24 %) against kerosene (65.7 +/- 0.8%), o-xylene (64.0 +/- 1%), and sunflower oil (44.7 +/- 0.5%). The composition of the EPS included two polymers-a negatively charged and a neutral one (similar to 3:1)-in which mannose and glucose were the main neutral monosaccharide constituents. Strain EG1HP4QL was able to utilize crude oil (35.3%) as the sole carbon source within 12 days. The minimum inhibitory concentrations of heavy metals [Zn(II), Cd(II), Pb(II), Ni(II), and Cu(II)] for strain EG1HP4QL were 1.0, 2.0, 2.0, 2.5, and 5 mM, respectively.