Sulfate reduction and heavy metal removal by a novel metal-resistant sulfate-reducing bacterium: mechanism and optimization

Simultaneous removal of carbon, sulfate and heavy metal was observed, by a novel metal-resistant Enterococcus avium strain BY7 sulfate reducing bacterium. Morphology of strain BY7 was observed by scanning electron microscopy, which was a long rod-shaped. Strain BY7 was a heterotrophic sulfate reducer which was able to use sucrose, glucose, citrate, ethanol, acetate and lactate as carbon source. Sulfate, sulfite and elemental sulfur could be utilized to produce sulfide by strain BY7. Elemental sulfur was produced as intermediate product during sulfate reduction. The optimal sulfate reduction by strain BY7 was observed with initial pH value of 8.0 under 30 degrees C, respectively. Tolerance to acidic condition and resistance to metal were observed by strain BY7. Heavy metals could be removed with high efficiency (>90%), with an order of Ni2+ > Pb2+ > Cu2+ > Fe3+ > Cd2+. When multicomponent metals were present, synergistic enhancement for metal removal was achieved. Because of the tolerance to acidic condition and resistance to metal, strain BY7 sulfate reducing bacteria might be used as an engineering bio-reagent for heavy metal removal and sulfate desalination.