Isolation and Phylogenetic Characterization of Microbial Consortia able to Degrade Aromatic Hydrocarbons at High Rates

Abstract

Two bacterial consortia, K-3 and No. 22, capable of degrading aromatic hydrocarbons in crude petroleum at high rates were screened from crude petroleum-contaminated soil. The K-3 consortium required saturated hydrocarbons (4 g/l) fractionated from crude petroleum for the efficient degradation (20%) of aromatics (4 g/l) within seven days, whereas the No. 22 consortium degraded 66% of aromatics (4 g/l) without supplementation with saturates in fourteen days. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and a colony isolation procedure gave five and fourteen DNA bands, and six and three different shaped colonies, respectively from the K-3 and No. 22 communities. Among the strains isolated from the K-3 consortium, Pseudomonas aeruginosa was the predominant species and decomposed aromatic hydrocarbons in the presence of saturates, while among the pure cultures from the No. 22 community, Burkholderia multivorans strain Y4 and Pandoraea sp. strain Y1 degraded aromatics at high rates without saturates. However, in a mixed culture of the strains, the degradation of aromatic hydrocarbons by a consortium of three strains, Hyphomicrobium facile strain Y3, strains Y1 and Y4, was nearly as efficient as that by the No. 22 community.