Plasmid mediated degradation of hydrocarbons in estuarine bacteria

Bacterial strains capable of degrading phenanthrene have been isolated from hydrocarbon-polluted sites in Chesapeake Bay using phenanthrene-overlaid agar plates. The isolates exhibited adherence to, and emulsification of, selected hydrocarbons. Two of the isolates, Flavobacterium sp. SB23 and an enteric, S53, were found to harbor plasmids. SB23 carried a 34 Mdal plasmid and S53 carried two plasmids of 34·3 Mdal and 2·9 Mdal molecular weight. Results of hydrocarbon adherence/emulsification tests indicated that the plasmid bearing strain SB23 exhibited minimal adherence to n-octane and n-hexadecane and strong emulsification of cyclohexylbenzene and 1, 2, 3, 4-tetrahydronaphthalene (tetralin), whereas the cured derivative lost ability to clear phenanthrene and emulsify the aromatic hydrocarbons. Upon transformation of the cured derivative with the 34 Mdal plasmid, the ability to clear phenanthrene was regained. A derivative of strain S53, cured of the 2·9 Mdal plasmid, lost the ability to emulsify tetralin but exhibited minimal adherence to the hydrocarbons. Radiorespirometric experiments, employing [9-14 C]-phenanthrene, confirmed the degradative ability of strain SB23. © 1986 Elsevier Applied Science Publishers Ltd, England.