EFFECT OF SODIUM-CHLORIDE CONCENTRATION ON GROWTH AND DEGRADATION OF EICOSANE BY THE MARINE HALOTOLERANT BACTERIUM MARINOBACTER-HYDROCARBONOCLASTICUS

The extremely halotolerant marine species Marinobacter hydrocarbonocla sticus presents an absolute requirement for NA(+) ions. When grown on acetate or eicosane, lag phase of cultures and generation time of cell s increased exponentially at NaCl concentrations greater than or equal to 1.0 M whereas the final biomass did not vary significantly (p less than or equal to 0.05) when salinity increased from 0.2 to 2.5 M NaCl . The increase in salinity induced morphological changes with increase d cell size. Scanning electron microscopy revealed extracellular vesic les on cells grown on eicosane. High salinity did not modify hydrocarb on biodegradation rates (80-90% biodegraded eicosane). This bacterium produced an extracellular emulsifying agent and adhered to hydrocarbon , but did not solubilize it before uptake. Both emulsification and adh erence took place during growth on eicosane, achieving contact between cells and hydrocarbon. An increase in external NaCl concentration mod ified emulsifying activity and adherence ability, but not the biodegra dation rates.