Sceening genes involved in alifatic and aromatic catabolic pathways in antarctic hydrocarbon-degrading microorganisms

RUBERTO L, MENDIVE F, MAC CORMACK WP

Villa carlos Paz, Cordoba, Argentina

Congreso; XXXVIII Reunión de SAIB 2002; 2002

SAIB

Petroleum hydrocarbons contamination is a global problem also affecting Antarctica, where soils near human settlements shows high levels of hydrocarbons. Analysis of genes involved in the catabolism of these compounds will allow a better understanding of these biochemical processes. In addition, analysis of these genes in bacterial communities couls provide tools to predict the soil response under a pollution event. As far as we know, there are not studies involving these genes in Antarctic microorganisms. Here, we present the initial results about the presence of the alkB, xylE and nahAc genes in four strains (ADH, DM1-41, M10dp and MP 2-4) and a consortium (M10) isolated from Antarctic contaminated soils.  Hydrocarbon degrading bacteria were grown on both, nutrient and mineral (with gas-oil) culture media. Genes were amplified by PCR. In all cases search for alkB and nahAc genes gave positive results. However, ADH strain (Rhodococcus sp) showed products of unexpected molecular weight. XylE gene amplification was positive for M10 and M10dp and negative for DM1-41 and MP 2-4. ADH showed an unexpected size fragment. This results suggest that the ADH strain could posses a different hydrocarbons catabolic pathways than those observed in many of the studied bacteria. This result agree with the observed with other psychrophilic Rhodococcus. Presence of gas-oil as sole carbon source seems to amplify the copy number of catabolic genes compared with the level observed when microorganisms grow in nutrient medium. Presence of alkB gene in all strains confirm the high degradation potential of aliphatic hydrocarbons observed in Antarctic soil.