Microbial Mechanisms Controlling the Fate of Fuel Component in Soil

摘要

A 3 year effort has been completed that examined the microbiological processes governing environmental fate of fuel components. Laboratory assays examining the potential biodegradation of quadracydane by aerobic soil microorganisms from a variety of contaminated habitats revealed that this proposed fuel additive was resistant to microbial attack. A combination of biochemical and molecular biological approaches were used to examine how microorganisms in a coal tar waste contaminated field site have adapted to metabolize the fuel component, naphthalene. A unique intermediary metabolite, cis-I ,2 dihydroxy-1 2- dihydronaphthalene, was extracted from groundwater and identified by GC/MS. This proved that naphthalene catabolism by indigenous microorganisms was in progress at the time of sampling. In addition, naphthalene catabolic mRNA, transcribed from the nahAc gene, was extracted from groundwater, reverse transcribed, amplified by PCR, and sequenced. These nucleotide sequences were compared to one another and to sequences from pure cultures; new genetic diversity for contaminant metabolism was discovered. Horizontal transfer of naphthalene catabolic genes was documented in site bacteria by discovering a highly conserved nahAc allene among diverse bacterial hosts. The mobile genetic element responsible fur metabolic adaptation was found to be a plasmid approximately 80 kb in size that was highly homologous to plasmid pDTGl originally described in a bacterium isolated from soil in Bangor, Wales, UK, decades ago.