BIODEGRADATION OF 3-CHLOROBENZOATE BY PSEUDOMONAS-PUTIDA-10.2

Pseudomonas putida 10.2, a 3-chlorobenzoate (3CBa)-degrading bacterium , was isolated from a soil sample obtained from an agricultural area i n Chiang Mai, Thailand. This bacterium could degrade 2 mM 3CBa very ra pidly with the concomitant formation of chloride ion when grown in min eral salt-yeast extract medium. The presence of glucose, lactose and p yruvate in the medium reduced the capability of this bacterium to degr ade 3CBa. Metabolites such as 3-chlorocatechol (3CC), catechol and cis ,cis-muconic acid (muconate) could be detected in the growth medium or in cell suspensions when 3CBa was used as the substrate. Furthermore, when crude enzyme extract prepared from 3CBa-grown P. putida 10.2 was incubated with 3CC, catechol and muconate could be detected in the re action mixtures. Thus, the biodegradation pathway of 3CBa by P. putida 10.2 was proposed to involve transformation of 3CBa to 3CC, The dehal ogenation step is believed to involve removal of chloride from 3CC to form catechol, which is subsequently converted to muconate.