FIG. 4.

Upstream pathway for the aerobic degradation of α-, γ-, and δ-HCH initiated by two successive dehydrochlorination reactions. 1,3,4,6-TCDN and 2,4,5-DNOL are shown in square brackets because they have not been demonstrated empirically. A further intermediate in δ-HCH degradation that has not been demonstrated empirically in the BHC-A strain is also shown in square brackets. This intermediate may be 3,4,5,6-TCOL, as was demonstrated for B90A. Note that the LinA, LinB, and LinC enzymes believed to catalyze several of the reactions are indicated, although direct evidence for the role of these enzymes in the strains indicated is not always available (see text).