PHA accumulation affects surfactant production and biofilms development in presence of hydrocarbons

PAULA M. TRIBELLI; CARLA DI MARTINO; NANCY I. LOPEZ; LAURA J. RAIGER- IUSTMAN

San Miguel de Tucuman

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

SAIB

Biofilms are complex bacterial structures with high stress and antibiotic resistance, and the prevalent way of living in the nature. We used three polyhydroxyalkanoate (PHA) producers: KA-08, isolated from a contaminated sludge, Pseudomonas extremaustralis and P. extremaustralis / pGEc4 (transformed with a plasmid containing alk genes), to test the capability to develop static biofilms in presence of diesel as sole carbon source. Two types of bacterial inocula- with or without PHA accumulation- were used to perform biofilm assays. Biofilm formation capability (BFC) was tested, after a week, by crystal violet (CV) microtiter plate assay. Planktonic cells were measured at 570nm and the BFC was determined as the ratio CV/OD . When the inocula had accumulated PHA, P. 570 extremaustralis / pGEc4 and KA-08 presented lower BFC than P. extremaustralis. KA-08 showed the lowest BFC, with high planktonic growth. We also evaluated surfactant production by “drop collapse” assay, showing that surfactant production was more important in all strains when PHA was previously accumulated. These could indicate an association between both metabolisms, for example the existence of a surfactant precursor provide by PHA degradation. These results are interesting to understand the hydrocarbon bioremediation in resistant forms of growth as biofilm.