Aerobic mineralization of γ-HCH by Pseudomonas paucimobilis UT26

¹⁴CO₂ was evolved from ¹⁴C-γ-hexachlorocyclohexane (γ-HCH) at a rate of 9.3% of the applied ¹⁴C during 4-days aerobical incubation with Pseudomonas paucimobilis UT26(UT26). 2,5-Dichloro-2,5-cyclohexadiene-1,4-diol (2,5-DDOL) and 2,5-dichlorohydroquinone(2,5-DCHQ) were newly identified as aerobic degradation products of γ-HCH. It was elucidated that 2,5-DDOL was degraded to 2,5-DCHQ, which was further degraded to mineralization. 2,5-DDOL was considered to be produced through unidentified intermediates, 1,3,4,6-tetrachlorocyclohexa-1,4-diene(1,4-TCDN) and 2,4,5-trichloro-2,5-cyclohexadiene-1-ol(2,4,5-DNOL), by two steps of dechlorinative hydroxylation. These results indicated that UT26 mineralized γ-HCH to CO₂ via 1,4-TCDN, 2,4,5-DNOL, 2,5-DDOL and 2,5-DCHQ. The aerobical mineralization of γ-HCH by UT26 is considered to be very noticeable from a viewpoint of bioremediation of the contaminated environment.