Reduction of nickel and uranium toxicity and enhanced trichloroethylene degradation to Burkholderia vietnamiensis PR1301 with hydroxyapatite amendment.

The use of hydroxyapatite (HA) to sequester metals at mixed waste sites may reduce metal toxicity and facilitate microbial degradation of cocontaminant organics. The constitutive trichloroethylene (TCE) degrader, Burkholderia vietnamiensis PR1301, grew at 34.1 and 1.7 mM Ni at pH 5 and 7, respectively, with 0.01 g mL(-1) HA compared to 17 and 0.85 mM Ni without HA. PR1 grew at 4.2 mM U at pH 5 and 7 with 0.01 g mL(-1) HA compared to 1.1 mM U without HA. A similar decrease in the toxicity of Ni and U in combination was observed with HA. The ability of PR1 to degrade TCE at 0.85, 1.7, and 3.4 mM Ni and at 0.42 and 1.1 mM U was examined. The presence of TCE resulted in a decreased tolerance of PR1 to Ni and U; however, HA facilitated TCE degradation in the presence of Ni and U, effectively doubling the metal concentrations at which TCE degradation proceeded. These studies suggest that metal sequestration via HA amendments may offer a feasible approach to reducing metal toxicity to microorganisms at mixed waste sites, thereby enhancing the degradation of cocontaminant organics.