Effectiveness of biostimulation and bioaugmentation techniques on the bioremediation of hydrocarbon-contaminated Antarctic soils

RUBERTO L, LO BALBO A, VAZQUEZ SC, MAC CORMACK

Cancun, Mexico

Congreso; International Symposium on Microbial Ecology, ISME-10; 2004

International Society of Microbial Ecology

Bioremediation are limited by temperature. Only cold-adapted microorganisms are suitable for bioremediation processes in cold areas, like hydrocarbon-contaminated soils nearby Antarctic stations. In these regions, the extreme climate conditions and the international regulations make essential the use of autochthonous microorganisms for bioaugmentation. During the last five years we have carried out field assays in Antarctica, working with microcosms (250-3000 g of soil) and mesocosms (1 m2 land plots). We analyzed how biodegradation activity is affected by biostimulation (N and P) and bioaugmentation with previously isolated Antarctic strains and consortia. Heterotrophic and hydrocarbon degrading aerobic bacteria, concentration of total (FT-IR) and some individual (GC) hydrocarbons, pH and soil water content were determined. Strains were characterized by biochemical profile and 16S rDNA sequencing. Two taxonomic groups were predominant among isolates from contaminated soils: Rhodococcus (isolated mainly from aliphatic-rich selective media) and Pseudomonas and related genera (isolated from aromatic-rich selective media). Autochthonous microflora from chronically polluted soils showed high degradation activity (81%) in 51-days bioremediation assays and non-significant differences were observed when bioaugmentation was assayed. On the contrary, significant effect of bioaugmentation was observed working with soils under acute contamination. Consortia showed site specificity. All strains and M10 consortia had alkB and nahAc genes. xylE was detected only in M10 and one strain isolated from it whereas for ADH strain an unexpected-size fragment was observed. This work shows the feasibility of in-situ bioremediation of Antarctic soils and suggests a site-specificity of the hydrocarbon-degrading bacterial consortia used for bioaugmentation.