Effects of nutrients and surfactants on pyrene mineralization and Mycobacterium spp. populations in contaminated soil

The impact of nutrient (KNO₃ and KH₂PO₄) or surfactant (Triton X-100 and Tergitol NP-10) amendments on the mineralization of ¹⁴C-pyrene and the indigenous Mycobacterium spp. community structure in a petroleum-contaminated soil were determined. All soil amendments enhanced pyrene mineralization with nutrients being slightly more effective than surfactants. 16S rRNA genes were PCR-amplified using Mycobacterium spp.-specific primers, separated by temperature gradient gel electrophoresis (TGGE), and prominent bands sequenced to compare the mycobacteria communities. The soil sample with the highest level of mineralization had no detectable changes in the community structure. Disappearance of a specific phylotype occurred in soils with lower mineralization rates. Phylogenetic analysis of sequenced TGGE bands indicated existence of novel strains.