POLYHYDROXYALKANOATE SYNTHESIS AFFECTS CELL ATTACHMENT TO HYDROCARBONS AND COPPER BIOSORPTION IN Pseudomonas sp. KA-08

CARLA DI MARTINO; ANTONELA COLONNELLA; SOFIA ORBEA; NANCY I. LOPEZ; LAURA J. RAIGER IUSTMAN

Mar del Plata

Congreso; X Congreso Argentino de Microbiologia General SAMIGE 2014; 2014

SAMIGE

Biological treatment is an innovative technology available for the cleanup of contaminated sites. In some cases, bioremediation includes the seeding of selected bacteria to enhance contaminant?s removal. In this case, strains that show high stress resistance and increased fitness are desirable. Pseudomonas sp. KA-08 was selected by its ability to grow in high amount of kerosene, diesel and xylene as sole carbon source, to tolerate high copper concentration, and to accumulate polyhydroxyalkanoates (PHA). We analyzed the relevance of PHA accumulation capabilities on cell membrane hydrophobicity and copper biosorption as a strategy to improve bioremediation. The PHAmutant, Pseudomonas KA-mut, was obtained by CrossOver PCR deletion of phaC1ZC2 genes. As Pseudomonas sp. KA-08 is highly tolerant to xylene and is able to degrade this compound, microbial attach to hydrocarbons (MATH) assays were performed using xylene as hydrocarbon to test bacterial adherence. Briefly, xylene was added to a cell suspension, the mixture was vortexed and left to stand to allow phases separation. Aqueous phase was taken, and OD600nm was measured. Under no PHA accumulating conditions (LB Medium), both strains presented no significant differences in their affinity to xylene but under PHA-accumulatiing conditions (ME + sodium octanoate), the wild type strain showed a significant lower affinity to xylene than the mutant strain (P< 0.0001). On the other hand, copper?s MIC was determined in LB broth 0.5X. Both strains showed a copper?s MIC close to 4mM. Due to this high resistance, copper biosorption assays were performed. The wild type strain showed a significant higher biosorption capability than the mutant strain and both of them adjusted to the Freundlich´s model. In conclusion, our results suggest that PHA accumulation capabilities affect bacterial outer membrane characteristics of Pseudomonas sp. KA-08 that are relevant for its fitness in hydrocarbon and heavy metal-contaminated environments.