DEGRADATION OF 1,2,3,4-TETRACHLOROBENZENE BY PSEUDOMONAS-CHLORORAPHISRW71

Pseudomonas chlororaphis RW71 mineralized 1,2,3,4-tetrachlorabenzene, a highly recalcitrant pollutant hitherto not known to be degraded by p ure cultures, as a sole source of carbon and energy, thereby releasing stoichiometric amounts of chloride. The transient excretion of tetrac hlorocatechol in the early growth phase suggests an initial attack by a dioxygenase to form the corresponding dihydrodiol which rearomatizes to the catechol, The activity of chlorocatechol 1,2-dioxygenase in cr ude cell extracts was found to be extraordinarily high towards 3 chlor ocatechol (ratio of 2.6 compared to catechol) and other chloracatechol s, including tetrachlorocatechol, which was transformed at a low but s ignificant rate. Further identification of tetrachloromuconic acid, 2, 3,5-trichlorodienelactone, 2,3,5-trichloromaleyl acetic acid, and 2,4- dichloro-3-oxoadipic acid as their methyl esters, together with high s pecific enzyme activities for chlorinated substrates, implicated a fun ctioning chlorocatechol pathway to be induced during growth.