Influence of crude oil contamination on the bacterial community of semiarid soils of Patagonia (Argentina)

Abstract

Autochthonous bacteriocenoses in semiarid soils in Patagonia were found to be capable of rapidly adapting to high contamination with crude oil. This adaptation at community level is due to the selective enrichment of hydrocarbon-utilizing bacteria always present in these soils. Immediately after a heavy contamination with crude oil, the autochthonous bacteriocenosis contained about 28% hydrocarbon-utilizing bacteria which could be classified into eight ecotypes with characteristic metabolic profiles. Mainly n-alkanes were used as growth substrates of representative strains. After seven months' exposure to crude oil, the bacteriocenosis consisted almost entirely of hydrocarbon-utilizing bacteria. At least fourteen ecotypes were distinguishable, and the majority of representative strains were able to metabolize a broad spectrum of aliphatic and aromatic hydrocarbons. Corresponding to the significant alteration of the physiological diversity, drastic changes to the taxonomic diversity were also found. Whereas at the beginning of the study the autochthonous bacteriocenoses were dominated by GRm-positive genera of the Actinomycetales (Dietzia, Gordona, Nocardia, Rhoabcoccus, Streptomyces) with high ecological potency, after just two months' exposure to crude oil, GRAMnegative bacteria (especially Pseudomonas srurzeri) became predominant within the hydrocarbonutilizing bacteriocenoses accompanied by some GRAM-positive genera of the Actinomycetales with a significantly lower abundance. These findings underline the importance of Pseudomonas and some genera of Actinomycetales for processes of natural attenuation and the technically supported in situ bioremediation of soil polluted by crude oil in Patagonia.

Biology of Pseudomonas stutzeri

“…Although P. stutzeri was one of the first alkane-degrading microorganisms identified-it was identified as Bacterium stutzeri (333)-few reports of crude oil-, oil derivative-, and/or aliphatic hydrocarbon-degrading P. stutzeri strains have appeared in the literature (81,95,156,163,166,268). In contrast, much information is available for other Pseudomonas species, such as P. aeruginosa, P. fluorescens, P. oleovorans, and P. putida (reviewed in reference 365).…”

Global Response to Desiccation Stress in the Soil Actinomycete Rhodococcus jostii RHA1

“…(33), are also known to have high desiccation tolerance (11). Actinomycetes are an abundant bacterial group in soil, with a critical role in the decomposition of organic matter.…”

Biosynthesis of fatty acids and triacylglycerols by 2,6,10,14-tetramethyl pentadecane-grown cells of Nocardia globerula 432

“…The isolation and characterization of N. globerula strain 432 were done in a previous study [4]. The strain was isolated from a soil sample collected in east Patagonia (Argentina).…”

“…The composition of the phenyldecane-derived intermediates indicated that the hydrocarbon was metabolized by L-oxidation and, to some extent, K-oxidation of the aliphatic side chain. The conversion of hydrocarbons into storage lipids during N-starvation is an interesting feature of these bacteria since these conditions are usually found in soil environments [4]. Moreover, these microorganisms have a broad metabolic spectrum for the transformation and degradation of di¡erent kinds of substrates, including a variety of alkanes, halogenated aliphatics and aromatics and other xenobiotic pollutants [5,6].…”