Genetic Engineering Applied to Microbial Degradation of Organophosphates

摘要

Marine and estuarine bacteria capable of degrading VX were isolated from enrichment cultures prepared using sediment samples collected from the Gulf of Mexico, the Chesapeake Bay, and the New York Bight as inocula. The enrichment media contained either tetriso (0,0-diisopropyl S-2-diisopropylaminoethyl phosphorothiolate) or IBP (0,0-diisopropyl S-benzyl phosphorothiolate) as a sole source of carbon and phosphorus. Bacterial isolates which exhibited enhanced growth in media containing IBP or tetriso were identified to genus or species, and tested for VX-degrading ability. Pure cultures grown in HEPES-buffered marine broth were monitored for VX-degradation using a gas chromatograph equipped with a flame photometric detector. First-order rate constants for VX hydrolysis, ranging from 1.73 to .00473/hrs, were 3.70 to 5.24 times higher than un-inoculated controls. Increases in pH were observed in paralleled experiments with media lacking VX, suggesting that the higher rates of degradation observed in bacterial cultures were due to pH-associated increases in rates of spontaneous hydrolysis. However, the enhanced growth of some of the strains in marine broth with VX, and the ability of two of the isolates to utilize IBP and/or tetriso as sources of phosphorus, provided evidence that these bacteria are capable of enzymatically degrading VX. (aw)