Degradation of 4,5-dichloroguaiacol by soil microorganisms.

No microorganisms could be isolated from chemostats or from a soil column fed with 4,5-dichloroguaiacol as the only carbon source. If guaiacol was added to chemostats with 4,5-dichloroguaiacol, either soil microbial consortia or guaiacol-degrading bacteria could dechlorinate the 4,5-dichloroguaiacol provided it was <0.2MM. A microbial consortium from farm soil removed 4,5-dichloroguaiacol under aerobic or anoxic conditions, with or without chlorolignin. Dichlorocatechol was the only 4,5-dichloroguaiacol-derived metabolite detected. In aerobic incubations, 4,5-dichlorocatechol was further degraded whereas under anoxic conditions it accumulated.

Metabolism of chlorinated guaiacols by a guaiacol-degrading Acinetobacter junii strain.

The metabolism of chlorinated guaiacols by a pure bacterial strain identified by its ability to use guaiacol as the sole carbon and energy source was studied. This strain, identified as Acinetobacter junii 5ga, was unable to grow on several chlorinated guaiacols and catechols. However, strain 5ga grown on guaiacol degraded 4- and 5-chloroguaiacol and 4,5-dichloroguaiacol. Under the same conditions, these cells did not degrade 6-chloroguaiacol, 4,6-dichloroguaiacol, 4,5,6-trichloroguaiacol, or tetrachloroguaiacol, suggesting that the substitution at the 6 position in the ring prevents metabolism of the compound. Degradation of 4-chloroguaiacol was dependent on the initial ratio between the chlorinated compound and viable cells. Transient formation of chlorocatechols resulting from incubation of cells with 4-chloroguaiacol or 4,5-dichloroguaiacol was suggested by UV spectroscopy. Gas chromatography analyses of samples from cultures of strain 5ga grown on guaiacol and incubated with 4- and 4,5-dichloroguaiacol confirmed the presence of 4-chlorocatechol and 4,5-dichlorocatechol, respectively. The formation of the latter was corroborated by gas chromatography-mass spectrometry. Thus, this strain is able to initiate metabolism of specific chlorinated guaiacols by O-demethylation. The starting chlorinated guaiacols and their O-demethylated metabolites inhibited the growth of A. junii 5ga on guaiacol.