Chromium tolerance and reduction potential of a Bacillus sp.ev3 isolated from metal contaminated wastewater

This study was aimed at assessing the ability of Bacillus sp.ev3 to reduce hexavalent chromium into its trivalent form. Bacillus sp.ev3 could tolerate Cr(6+) (4800 microg/mL), Pb(2+) (800 microg/mL), Cu(2+) (200 microg/mL), Cd(2+) (50 microg/mL), Zn(2+) (400 microg/mL), Ni(2+) (4000 microg/mL) and Hg(2+) (50 microg/mL). Bacillus sp.ev3 showed optimum growth at 37 degrees C and pH at 7. Bacillus sp.ev3 could reduce 91% of chromium from the medium after 96 h and was also capable to reduce 84% chromium from the industrial effluents after 144 h. Cell free extracts of Bacillus sp.ev3 grown in the presence of Cr showed reduction of 70%, 45.6% and 27.4% at concentrations of 10 microg Cr(6+)/mL, 50 microg Cr(6+)/mL and 100 microg Cr(6+)/mL, respectively.