Although dieldrin (1,2,3,4,10,10-hexachloro- 6,7-epoxy-1 ,4 ,4a ,5 ,6 ,7 ,8, 8a-octahydro-1 ,4-endo, exo-5, 8-dimethanonaphthalene) metabolism by mammals (F. Korte and H. Arent, Life Sci. 4:2017, 1965) and insects (D. F. Heath and M. Vanderkar, Brit. J. Ind. Med. 21:269, 1964) has been reported, little is known about the degradation of this important pesticide by microorganisms. Korte et al. (Ann. Chem. Liebigs 656:135, 1962) and Chacko et al. (Science 154: 893, 1966) reported that a number of ubiquitous microorganisms were incapable of degrading dieldrin; however, more recently Matsumura and Boush (Science 156:959, 1967) isolated several species of Pseudomonas and Bacillus which could degrade dieldrin, from a number of soil samples having similar activity. They did not specifically attempt to identify the dieldrin metabolites formed, but they did suggest, on the basis of an identical RF value with an authentic control that 6,7-trans-dihydroxydihydroaldrin (aldrin diol) might be a major product. Work carried out concurrently in this laboratory has shown that another ubiquitous bacterium, Aerobacter aerogenes, converts dieldrin in vitro to a compound chromatographically similar to 6,7-trans-dihydroxydihydroaldrin.
