Microbial diversity of emalahleni mine water in South Africa and tolerance ability of the predominant organism to vanadium and nickel

Abstract

The present study aims firstly at determining the microbial diversity of mine-water collected in Emalahleni, South Africa and secondly isolating and characterizing the most dominant bacterial species found in the mine water in terms of its resistance to both V5+ and Ni2+ in a modified wastewater liquid media. The results revealed a microbial diversity of 17 orders, 27 families and 33 genera were found in the mine-water samples with Marinobacteria (47.02%) and Anabaena (17.66%) being the most abundant genera. Considering their abundance in the mine-water samples, a species of the Marinobacter genera was isolated, identified, and characterised for metal tolerance and removal ability. The MWI-1 isolate (Marinobacter sp. MWI-1 [AB793286]) was found to be closely related to Marinobacter goseongensis at 97% of similarity. The isolate was exposed to various concentrations of Ni 2+ and V5+ in wastewater liquid media and its tolerance to metals was also assessed. The MWI-1 isolate could tolerate V5+ and Ni2+ separately at concentrations (in terms of MIC) up to 13.41±0.56 mM and 5.39±0.5 mM at pH 7, whereas at pH 3, the tolerance limit decrease to 11.45±0.57 mM and 2.67±0.1 mM, respectively. The removal of V5+ and Ni2+ in liquid media was noted to gradually decrease with a gradual increase of the test metals. A significant difference (p<0.05) between V5+ and Ni2+ removal was noted. Marinobacter sp. MWI-1 achieved the maximum permissible limit of 0.1 mg-V5+/L prescribed by UN-FAO at 100 mg/L, while at 200 mg/L only V5+ was removed at approximately 95% and Ni2+ at 47%. This study suggests that mine-water indigenous microorganisms are the best solution for the remediation of polluted mine water. © 2014 Kamika, Momba.