Biodegradation of a crude oil by three microbial consortia of different origins and metabolic capabilities.

Microbial consortia were obtained three by sequential enrichment using different oil products. Consortium F1AA was obtained on a heavily saturated fraction of a degraded crude oil; consortium TD, by enrichment on diesel and consortium AM, on a mixture of five polycyclic aromatic hydrocarbons [PAHs]. The three consortia were incubated with a crude oil in order to elucidate their metabolic capabilities and to investigate possible differences in the biodegradation of these complex hydrocarbon mixtures in relation to their origin. The efficiency of the three consortia in removing the saturated fraction was 60% (F1AA), 48% (TD) and 34% (AM), depending on the carbon sources used in the enrichment procedures. Consortia F1AA and TD removed 100% of n-alkanes and branched alkanes, whereas with consortium AM, 91% of branched alkanes remained. Efficiency on the polyaromatic fraction was 19% (AM), 11% (TD) and 7% (F1AA). The increase in aromaticity of the polyaromatic fraction during degradation of the crude oil by consortium F1AA suggested that this consortium metabolized the aromatic compounds primarily by oxidation of the alkylic chains. The 500-fold amplification of the inocula from the consortia by subculturing in rich media, necessary for use of the consortia in bioremediation experiments, showed no significant decrease in their degradation capability.