Isolation and Molecular Detection of Polycyclic Aromatic Hydrocarbon-Degrading <i>Mycobacterium</i> spp. from the Shenfu Wastewater Irrigation Area in China

Abstract

Mycobacterium spp. with the ability to degrade polycyclic aromatic hydrocarbons (PAHs) have attracted great attention. This study aims to isolate pyrene-degrading Mycobacterium spp. through direct plating and selective enrichment from sediment and paddy soil from several sites in Shenfu Wastewater Irrigation Area, and the diversity, catabolic genes and substrate utilization patterns of these pyrene-degrading Mycobacterium isolates was investigated. The Mycobacterium community dynamics was monitored during enrichment cultures by Denaturing Gradient Gel Electrophoresis (DGGE) to determine whether the Mycobacterium sp. detected in DGGE gels was successfully recovered. The results showed that a total of 20 unique Mycobacterium isolates were collected including 3 strains from direct plating and 17 from enrichment cultures. In addition to pyrene, most of the isolates could also degrade phenanthrene and fluoranthene and contained nidA and nidA3 genes, and only half of isolated strains were found to possess the pdoA2 gene. DGGE results showed that the Mycobacterium community had a shift in diversity during enrichment process. phylogenetic analysis based on 16SrDNA sequences from bands excised from DGGE gels and from these isolates revealed that isolated Mycobacterium spp. were represented of bands excised from DGGE gels in a small proportion. This collection of isolates will be valuable in bioremediation of PAH-contaminated sites.