Biodegradation of 4-chloroindole by Exiguobacterium sp. PMA

Exiguobacterium sp. PMA utilized 4-chloroindole as its sole source of carbon and energy. The effect of initial concentrations of substrate on the 4-chloroindole degradation was studied and observed that strain PMA was capable of degrading 4-chloroindole up to concentration of 0.5mM. The degradation pathway of 4-chloroindole was studied for Exiguobacterium sp. PMA based on metabolites identified by gas chromatography-mass spectrometry. 4-Chloroindole was initially dehalogenated to indole that was further degraded via isatin, anthranilic acid, and salicylic acid. The potential of strain PMA to degrade 4-chloroindole in soil was monitored using soil microcosms, and it was observed that the cells of strain PMA efficiently degraded 4-chloroindole in the soil. The results of microcosm studies show that strain PMA may be used for bioremediation of 4-chloroindole-contaminated sites. This is the first report of the bacterial degradation of 4-chloroindole.