Biodegradation of phenol by antarctic bacterium Rhodococcus baikonurensis strain AQ5-001 in the presence of heavy metals

In the past decades, the applications of indigenous microbes obtained from hydrocarbon-polluted environments in remediating phenol have proven effective even though phenol is highly toxic to microorganisms. The remediation of phenol in cold and polluted environments including Antarctica requires the usage of microorganisms that are able to adapt to low temperatures and can withstand the toxicity of phenol. Henceforth, this study is aimed at identifying the phenol-degrading ability of the Antarctic bacterium and its tolerance to 10 heavy metalsAs, Ag, Cd, Co, Cu, Cr, Hg, Ni, Pb and Zn. The bacterium was grown on phenol agar and supplemented with 0.2 g/L of phenol. Identification of the bacterium was found to be Gram-positive, catalase-positive and oxidase-negative. Through the analysis of the 16S rRNA sequence gene, the strain belonged to the Rhodococcus genus. Phenol degradation and optical density was monitored daily using 4-aminoantipyrine spectrophotometric assay method. The phenol-degrading abilities of the Antarctic bacterium was inhibited only by 1 ppm of Ag, Cd and Hg. Heavy metals Cd and Hg had values p0.05. It was found that Ag began its inhibition at 0.9 ppm, Cd at 0.8 ppm and Hg at 0.5 ppm. The IC50 of Hg was found to be 0.5 ppm. The tolerance towards heavy metals of phenol-degrading bacterium was proved ideal and has the potential to be used in remediation and waste-water treatments in low temperature environments