EFFECTS OF OIL-SPILL DISPERSANTS AND DRILLING-FLUIDS ON SUBSTRATE-SPECIFICITY OF MARINE-BACTERIA

The effects of oil spill dispersants and drilling fluids on the sizes of populations of specific heterotroph subgroups of marine bacteria we re monitored in this study. The bacteria were isolated from drill cutt ings recovered from Agbara -- an offshore oilfield located some 100 na utical miles off the Atlantic coast of Nigeria. Numbers of cellulolyti c, proteolytic, starch-hydrolysing and lipolytic bacteria in the drill cuttings were monitored for 28 days in the presence of oil spill disp ersants and drilling fluids. The percentages of these bacterial subgro ups within the total heterotrophic population enumerated on tryptic so y agar (10% with 3% NaCl) fluctuated between 3.0 and 17.0%, 0.0 and 27 .0%, 4.0 and 25.0% and 3.0 and 18.0% for cellulolytic, proteolytic, st arch-hydrolysing and lipolytic bacteria respectively. These results in dicate that oil spill dispersants and drilling fluids affect the abili ty of marine bacteria to metabolize these substrates in the environmen t. (C) 1996 Elsevier Science Ltd