Effect of different biostimulation strategies on microbial community structure of a chronically hydrocarbon contaminated-soil in Antarctica

DIAS R; RUBERTO L; HERNANDEZ E; DEL PANNO MT; MAC CORMACK WP

Seattle

Congreso; 13º International Symposium on Microbial Ecology (ISME13); 2010

International Society of Microbial Ecology

Biostimulation seems to be the best bioremediation strategy to enhance the natural biodegradation process in chronically contaminated soils from cold climate. Therefore, selection of the most efficient nutrients is an essential step. Also the presence of surface-active compounds has proved to enhance the removal of hydrocarbon. The aim of this study was to evaluate the effect of different nutrients sources, in the presence or absence of a surfactant Brij®700, on the bioremediation of chronically hydrocarbon-contaminated soils from Jubany Station, Antarctica. Inorganic salts (NSS) and fish meal (FM), alone and with Brij®700 (NSSB and FFB), were analyzed. Additionally, a commercial product (CP, mixture of enzymes, nutrients and surfactants) and an untreated control (CC) were evaluated. The systems were monitored during 45 days by counting heterotrophic (HB) and hydrocarbon-degrading bacteria (HDB) and measuring total hydrocarbons concentration (TH). Changes in the soil bacterial community structure were studied by PCR-DGGE. All evaluated nutrients sources, with or without B, increased HDB more than three orders of magnitude except CP, which only increased one order compared with CC. However, at the end of the assay, only CP showed a significant hydrocarbon removal (70%) compared with the CC (40%). DGGE profiles from FM and FMB showed that fish meal produced a shift in bacterial community structure compared with the others systems. CC, CP, NSS and NSSB stimulated similar communities. The CP bacterial community at the end of the assay showed a similarity of 80% compared with those observed in CC at the beginning of the assay. The results showed that the CP represents an attractive option because it exhibited the best degradation efficiency combined with the minimal changes in soil bacterial community. This fact suggests that CP would stimulate mainly the most efficient hydrocarbon-degrading bacterial present in the natural soil community.