FACTORS AFFECTING GROWTH OF AN N-HEXADECANE DEGRADER ACINETOBACTER SPECIES ISOLATED FROM A HIGHLY POLLUTED URBAN RIVER

Microbiological analyses of an urban river continuously polluted with hydrocarbons resulted in the isolation of 33 strains of Gram negative bacteria capable of growing on n-hexadecane. One Acinetobacter strain (B2-2) was selected and several parameters that are likely to affect t he growth of this strain on n-hexadecane were evaluated. Temperature, pH, inoculum size, effect of the presence of yeast extract and n-hexad ecane concentration were analysed. At pH 7-5, 25-degrees-C and an init ial concentration of 0.5% of n-hexadecane, 82% of the hydrocarbon was degraded in the first stage of the culture (50 h) and, at 124 h only 1 0% of the n-hexadecane remained undegraded. During growth, an extracel lular surfactant was produced and a decrease in the surface tension of the culture media was observed. This study shows how the performance of an hexadecane degrader strain is affected by several factors and th erefore could be helpful for the design of strategies for the bioremed iation of contaminated sites.