Characterization of a hydrocarbon degrading psychrotrophic Antarctic bacterium

Abstract

Antarctic soil chronically exposed to gas-oil was analysed in order to isolate and study the growth conditions of hydrocarbon degrading bacteria. Soil samples taken near the shoreline in Jubany Station (King George Island, South Shetland Islands) were used as inoculum in liquid culture media with crude oil as sole carbon source. A psychrotrophic Acinetobacter strain was isolated and selected for further investigations. Effects were studied of temperature, initial pH, NaCl concentration and different chemical structure of the hydrocarbon on growth. Degradation rate was determined with n-dodecane and n-hexadecane. Growth of Acinetobacter ADH-1 showed no differences at an initial pH of 7.0, 7.5 and 8.0. Optimum temperature ranged between 25–30°C but the strain was capable of growing on n-dodecane at 4°C. Growth was observed in the presence of 3.5% NaCl. A decrease in the surface tension values was observed in the culture broth during the first 20 h of incubation (from 68 din cm⁻¹ to 31 din cm⁻¹). This proved to be related to the cellular fraction of the culture. The study shows that Acinetobacter ADH-1 is a psychrotrophic bacteria able to grow with hydrocarbons as sole carbon and energy source and could be potentially useful to design bioremediation processes in temperate and cold climate areas.