Biostimulation and bioaugmentation of gasoil contaminated Antarctic soils

RUBERTO, L., LO BALBO, A., VAZQUEZ, S, FLOCCO, C, GIULIETTI, A.M., MAC CORMACK, W.P

Basilea, Suiza

Congreso; 11th European Congress on Biotechnology; 2003

European federation of Biotechnology

Bioremediation is an effective tool to improve contaminant degradation in soils. Since temperature is one of the mains limiting factors of these processes, only psychrotrophic and psychrophilic microorganisms are adequate to develop bioremediation techniques in cold areas. Although bioaugmentation has been proposed as the most effective strategy by some researchers, others have reported that optimization of physical and chemical factors of soil matrix enhance the hydrocarbon-degrading activity of the natural microflora, making unnecessary the use of bioaugmentation techniques. In Argentina, many cold climate areas showed hydrocarbon-contaminated soils. This problem includes Antarctic areas nearby scientific stations, where the extreme climate conditions as well as the international regulations make essential the use of autochthonous microorganisms in bioaugmentation techniques. Objective: to analyze the effect of bioaugmentation and biostimulation on the efficiency of in situ hydrocarbon bioremediation of chronically contaminated Antarctic soils. For this purpose, microcosms (3 kg of chronically contaminated Antarctic soil) were designed and exposed to the Antarctic climate conditions in order to evaluate: abiotic elimination, activity of autochthonous microflora, biostimulation (addition of N and P) and bioaugmentation with bacterial strains and consortia). Viable counts, hydrocarbon-degrading microorganisms, total hydrocarbon concentration (IR spectrometry) and differences in hydrocarbon patterns among treatments (GC-MS) were determined. Changes in aliphatic and aromatic fractions were inferred from p-xylene and tetradecane concentration (GC-MS) which were used as markers compounds. Results: biostimulated autochthonous microflora showed high degradation activity (81%) in 51 days long bioremediation assay, resulting in similar levels compared with those where bioaugmentation were applied. Bacterial consortia previously isolated from the same contaminated area under study showed higher hydrocarbon elimination efficiency (86%) than consortia isolated from other chronically polluted Antarctic region. Conclusions: Results showed the feasibility of in situ bioremediation processes in Antarctic soils and suggested a site -specificity of the hydrocarbon-degrading bacterial consortia.