EVALUATION OF TRIBUTYLTIN RESISTANCE IN MARINE SEDIMENT BACTERIA

Tributyltin (TBT) resistance of aerobic and anaerobic bacteria isolate d from TBT-contaminated coastal sediments in Arcachon Bay, France, was determined and compared with taxonomically similar bacteria originati ng from diverse non-TBT-contaminated environments. The minimum inhibit ory concentrations (MICs) showed that TBT was toxic to most of the bac teria studied at concentrations above 2.1 mu M (0.7 mg/L) for clostrid ia, 76 mu M (25 mg/L) for pseudomonads, and 3 mM (1000 mg/L) for enter obacteria. The aerobic or facultative anaerobic Gram-negative bacteria (pseudomonads and enterobacteria) presented the highest TBT tolerance . No difference in TBT resistance was observed between strains origina ting from the polluted site and strains originating from non-TBT-pollu ted environments (thermal muds, Hospital of Bordeaux, etc.), suggestin g that a TBT-polluted environment did not select for more specific res istant bacteria. It should be noted that the bacteria tested were foun d to be tolerant to TBT concentrations 1000 times higher than those fo und in the polluted site. Further, all strains presented the same patt ern of metal and pharmaceutical antibiotic sensitivity despite the ori gin of the environment (TBT-polluted or non-TBT-polluted sediments). S ix strains of Pseudomonas stutzeri isolated from Arcachon Harbor and o ne strain of Pseudomonas aeruginosa originating from the bacterial col lection of Bordeaux Hospital have been selected for their TBT resistan ce. As antibiotic resistance, metal or organometal resistance can be p lasmid mediated. However, among these TBT-resistant strains no plasmid was detected.