Effect biostimulation and bioaugmentation on the efficiency of hydrocarbon biodegradation of chronically contaminated Antarctic soils

VÁZQUEZ, S. C., NOGALES, B., RUBERTO, L., HERNANDEZ, E., LOBALBO A. CHRISTIE-OLEZA, J., BOSCH, R., LALUCAT, J., MAC CORMACK, W.P

Malasia

Congreso; 3rd Malaysian International Seminar on Antarctica; 2007

Universiti Malaysia Sabah, the Academy of Sciences Malaysia (ASM), International Council for Science (ICSU)-SCAR, Universiti of Malaya and the Ministry of Science, Technology & Innovation

  Although some studies found that bioaugmentation is an effective strategy for hydrocarbon removal, others have reported that biostimulation of the natural microflora is enough to optimize biodegradation of the pollutants, making unnecessary the use of bioaugmentation techniques. In Antarctica, the extreme climate conditions as well as the international regulations prevent the use of non-indigenous microorganisms. For this reason, the knowledge of the autochthonous hydrocarbon-degrading microorganisms is essential to develop bioremediation techniques in this continent. In this work we analyzed the effect of bioaugmentation and biostimulation on the efficiency of hydrocarbon degradation in Antarctic soils. Land plots (1m2) were exposed to the Antarctic climate conditions. Activity of autochthonous microflora, biostimulation and bioaugmentation with two Antarctic bacterial consortia (M10 and J13) were evaluated. Viable counts, hydrocarbon-degrading bacteria and hydrocarbon concentration were determined. After 48 d, untreated soil showed 10% of hydrocarbon removal whereas biostimulated systems (either bioaugmented or not) showed significantly higher levels (52-65%). Bacterial communities were characterized by T-RFLP analysis of PCR amplified 16S rDNA, at three different times. There was an increase in the evenness but no major variation in Shannon diversity due to the replacement of the main bacterial population by several different populations, which became abundant in treated soils. No differences were observed between biostimulated and bioaugmented plots; bacterial counts were similar and the T-RFs in consortia were not detected in the soil plots profiles, evidencing that the consortia added could not establish. Several hydrocarbon degradation genes were detected by dot-blot analysis in all samples indicating the existence of a pool of catabolic genes in this contaminated soil. Detection of catabolic genes increased during treatment even in control plot and therefore the changes could not be attributed to bioremediation treatment. In conclusion, hydrocarbon bioremediation in treated plots was successful and it resulted in changes in bacterial communities.