Resistance of sulphate reducing bacteria to three common heavy metals and a novel hydrogenase production in Ni-grown culture

Biofilms collected from an acid mine drainage outflow were examined for their capacity to immobilize metals from solution. Sulphate reducing bacterial consortia enriched from these biofilms possessed heavy metal resistance to Cu2+, Ni2+, and Zn2+up to maximum resistance values of 10 ppm Cu2+, 200 ppm Ni2+ and 75 ppm Zn2+. Transmission electron microscopy of the Ni-response of the ‘Atlin’ consortium, which possessed a high tolerance to Ni (up to 200 ppm) revealed the presence of donut-shaped protein complexes in the culture supernatant. A Benzyl Viologen (BV) hydrogenase assay confirmed hydrogenase activity and was combined with a modified Lowry protein assay data to determine a maximum hydrogenase activity of 0.037 pmol H2 consumed per minute per mg of protein at 25°C. Upon addition of synthetic AMD water, the acidified SRB culture precipitated Ni-rich material, resulting in a maximum Ni-recovery rate of 95