Degradation of aromatic hydrocarbons by the Rhodococcus wratislaviensis KT112-7 isolated from waste products of a salt-mining plant

Abstract

Degradation of aromatic hydrocarbons by the Rhodococcus wratislaviensis KT112-7 isolated from technogenic mineral waste products of the BKRU1 “Uralkalii” plant was investigated (Berezniki, Perm krai). The R. wratislaviensis KT112-7 was shown to utilize increased concentrations of o-phthalic (o-PA) (8 g/L) and benzoic (BA) (3.4 g/L) acids. The strain grows with o-PA, BA, and biphenyl at a NaCl content of up to 75, 90 and 100 g/L in the culture medium, respectively. Based on an analysis of the metabolic profile and nucleotide sequences of the bphA1, benA, and phtB genes, the strain KT112-7 was found to degrade o-PA via the formation of 3,4-dihydroxyphthalic and 3,4-dihydroxybenzoic acids. Degradation of biphenyl proceeds via the formation of BA and then at low concentrations of NaCl (up to 50 g/L) via the formation of 4-hydroxybenzoic acid with its subsequent oxidation, while at high concentrations of NaCl (over 60 g/L)-via the direct oxidation of benzoic acid to resultant catechol. These data indicate that the Rhodococcus wratislaviensis KT112-7 is a promising strain in the development of new biotechnologies directed for utilization (transformation) of aromatic compounds, including the conditions of increased mineralization.