Bioremediation of hydrocarbon contaminated environments: role of

DI MARTINO CARLA; TRIBELLI PAULA M.; LÓPEZ NANCY; RAIGER IUSMAN LAURA

Villa Carlos Paz, Cordoba

Workshop; II Argentine Workshop in Current Topics in Pseudomonas and Burkordelia Research; 2009

SAMIGE

One of the most desirable characteristic for a microorganism suitable for hydrocarbon bioremediation is its aptitude to enhance the hydrocarbon bioavailability i.e by the production of tensoactive agents like biosurfactants. In the present work we propose to isolate biosurfactant producer bacteria from natural environments and characterize the tensoactive agent. Aliquots of an activated sludge obtained from a petrochemical industry from La Plata (Argentina) were grown in E2 minimal medium with diesel or kerosene as sole carbon source at 30°C and 250 rpm until turbidity development. We isolated 20 clones, in E2 solid media, that were capable of growing with diesel or kerosene as sole carbon source and only four of them were able to accumulate PHA in the presence of sodium octanoate. PHA accumulation was analyzed by Nile Blue stain. Two of those strains were selected by their surfactant capability: KA-08 and KB-08. On the other hand, an Antarctic isolation characterized in our lab P. extremaustralis/pGEc4, was assayed as well. To analyze the presence of surfactant in the three cultures, free cell supernatant were tested by de “drop collapse” assay. The putative surfactants were pre-purified by acid precipitation followed by organic extraction, and the chemical nature of the compounds was analyzed by TLC. To study the hydrocarbon solubilization ratio in the culture media, free cell supernatants were extracted with hexane and analyze with GC. To characterize the two new isolations, a multi-test API20NE and a rRNA16S sequencing was performed resulting that both strains belong to the genus Pseudomonas. As conclusion, three strains were assayed for biosurfactant production: P. extremaustralis/pGEc47, Pseudomonas sp. KA-08 and Pseudomonas sp. KB-08 (FN421340 and FN421341, respectively). The chemical nature of the surfactant in  P. extremaustralis seems be a lipoprotein, while Pseudomonas sp. KA-08 and Pseudomonas sp. KB-08 seem to produce a glycolipid according their TLC development pattern. On the other hand, the GC patterns shown that the solubilization/ degradation pattern differs from strain to strain.