Long Term Interactions of Microorganisms and Prudhoe Bay Crude Oil in Tundra Soils at Barrow, Alaska

Oil was recovered from tundra soils two and seven years after spillage. Oil persisted in the upper soil layer. The depth of penetration appears to depend on soil moisture and drainage characteristics. Maximal penetration seems to occur within one year of spillage. Biodegradation of the oil was indicated by changes in the ratio of gas chromatographically resolved to unresolved components. Individual components appear to be preferentially degraded, but no evidence was found for significant preferential degradation of structural classes of hydrocarbons. Numbers of microorganisms were different in oil contaminated and reference soils generally showing continued enrichment, but in some soils showing inhibition of microbial populations

Hydrocarbons and Microbial Activities in Sediment of an Arctic Lake One Year After Contamination with Leaded Gasoline

Hydrocarbons were found to persist in the sediment of an Arctic lake one year after the lake was accidentally contaminated with leaded gasoline. The contaminating gasoline was continuing to spread from the original site of contamination. High numbers of hydrocarbon utilizing microorganisms were found in the contaminated sediment. Rates of nitrogen fixation did not appear to be affected by hydrocarbon contamination, but potential denitrification activities appeared to be altered by the gasoline. Fertilizer application resulted in a moderate decrease of hydrocarbon concentrations in the sediment

Fate of Crude and Refined Oils in North Slope Soils

Prudhoe Bay crude oil and refined diesel fuel were applied to five topographically distinct tundra soils at Prudhoe Bay, Alaska. The penetration of hydrocarbons into the soil column depended on soil moisture and drainage characteristics. Biodegradation, shown by changes in the pristane to heptadecane and resolvable to total gas chromatographic area ratios, appeared to be greatly restricted in drier tundra soils during one year exposure. Some light hydrocarbons, C9-C10, were recovered from soils one year after spillages. Hydrocarbons were still present in soils at Fish Creek, Alaska, contaminated by refined oil spillages 28 years earlier, attesting to the persistence of hydrocarbons in North Slope soils

Evidence for Acquisition in Nature of a Chromosomal 2,4-Dichlorophenoxyacetic Acid/(alpha)-Ketoglutarate Dioxygenase Gene by Different \u3ci\u3eBurkholderia\u3c/i\u3e spp.

We characterized the gene required to initiate the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) by the soil bacterium Burkholderia sp. strain TFD6, which hybridized to the tfdA gene of the canonical 2,4-D catabolic plasmid pJP4 under low-stringency conditions. Cleavage of the ether bond of 2,4-D by cell extracts of TFD6 proceeded by an (alpha)-ketoglutarate-dependent reaction,characteristic of TfdA (F. Fukumori and R. P. Hausinger, J. Bacteriol. 175:2083-2086, 1993). The TFD6 tfdA gene was identified in a recombinant plasmid which complemented a tfdA transposon mutant of TFD6 created by chromosomal insertion of Tn5. The plasmid also expressed TfdA activity in Escherichia coli DH5(alpha), as evidenced by enzyme assays with cell extracts. Sequence analysis of the tfdA gene and flanking regions from strain TFD6 showed 99.5% similarity to a tfdA gene cloned from the chromosome of a different Burkholderia species (strain RASC) isolated from a widely separated geographical area. This chromosomal gene has 77.2% sequence identity to tfdA from plasmid pJP4 (Y. Suwa, W. E. Holben, and L. J. Forney, abstr. Q-403, in Abstracts of the 94th General Meeting of the American Society for Microbiology 1994.). The tfdA homologs cloned from strains TFD6 and RASC are the first chromosomally encoded 2,4-D catabolic genes to be reported. The occurrence of highly similar tfdA genes in different bacterial species suggests that this chromosomal gene can be horizontally transferred