Degradation of polychlorinated phenols by Streptomyces rochei 303

Abstract

The strain Streptomyces rochei 303 (VKM Ac-1284D) is capable of utilizing 2-chloro-, 2,4-, 2,6-dichloro- and 2,4,6-trichlorophenols as the sole source of carbon. Its resting cells completely dechlorinated and degraded 2-, 3-chloro-; 2,4-, 2,6-, 2,3-, 2,5-, 3,4-, 3,5-dichloro-; 2,4-, 2,6-dibromo-; 2,4,6-, 2,4,5-, 2,3,4-, 2,3,5-, 2,3,6-trichlorophenols; 2,3,5,6-tetrachloro- and pentachlorophenol. During chlorophenol degradation, a stoichiometric amount of chloride ions was released and chlorohydroquinols were formed as intermediates. In cell-free extracts of S. rochei, the activity of hydroxyquinol 1,2-dioxygenase was found. The enzyme was induced with chlorophenols. Of all so far described strains degrading polychlorophenols, S. rochei 303 utilized a wider range of chlorinated phenols as the sole sourse of carbon and energy.

Purification and characterization of 6-chlorohydroxyquinol 1,2-dioxygenase from Streptomyces rochei 303: comparison with an analogous enzyme from Azotobacter sp. strain GP1

“…VKM AC-1284D. This strain was shown to be able to degrade mono-, di-, tri-, and tetrachlorophenols and pentachlorophenol (13,38). To obtain the biomass for the purification of enzyme, the culture was grown in a 15-liter fermentor in mineral salt medium containing the following (in grams per liter): KH 2 PO 4 , 0.1; (NH 4 ) 2 HPO 4 , 2.0; Na 2 SO 4 , 0.1; MgSO 4 ⅐ 7H 2 O, 0.3; and KNO 3 , 2.0, with repeated additions of 0.1 mM 2,4,6-trichlorophenol as the sole source of carbon and energy.…”

“…These results led us to suggest that two different dioxygenases play a role in the cleavage of the trihydroxylated aromatic ring: 6-chlorohydroxyquinol 1,2-dioxygenase in the ring fission of 6-chlorohydroxyquinol, the proposed intermediate of 2,4,6-trichloro-and 2,6-dichlorophenol degradation, and a second dioxygenase in the cleavage of hydroxyquinol, the proposed intermediate of 2,4-dichloro-and 2-chlorophenol degradation ( Fig. 1) (13).…”

“…In this pathway, chlorocatechols formed by introduction of a second hydroxy group are subjected to intradiol cleavage. In the case of chlorophenol degradation through the chlorohydroquinone pathway, the introduction of a third hydroxy group leads to the formation of hydroxyquinol or chlorohydroxyquinol (3,13). Both unsubstituted and chlorinated 1,2,4-trihydroxybenzene were shown to be subject to ortho cleavage in Streptomyces rochei 303 (13).…”

“…In the case of chlorophenol degradation through the chlorohydroquinone pathway, the introduction of a third hydroxy group leads to the formation of hydroxyquinol or chlorohydroxyquinol (3,13). Both unsubstituted and chlorinated 1,2,4-trihydroxybenzene were shown to be subject to ortho cleavage in Streptomyces rochei 303 (13). Extracts from cells grown in the presence of 2-chloro-or 2,4-dichlorophenol were found to prefer hydroxyquinol over 6-chlorohydroxyquinol as a ring fission substrate, whereas extracts from cells grown on 2,6-dichloro-or 2,4,6-trichlorophenol showed a preference for the chlorinated substrate (13).…”

“…Both unsubstituted and chlorinated 1,2,4-trihydroxybenzene were shown to be subject to ortho cleavage in Streptomyces rochei 303 (13). Extracts from cells grown in the presence of 2-chloro-or 2,4-dichlorophenol were found to prefer hydroxyquinol over 6-chlorohydroxyquinol as a ring fission substrate, whereas extracts from cells grown on 2,6-dichloro-or 2,4,6-trichlorophenol showed a preference for the chlorinated substrate (13). These results led us to suggest that two different dioxygenases play a role in the cleavage of the trihydroxylated aromatic ring: 6-chlorohydroxyquinol 1,2-dioxygenase in the ring fission of 6-chlorohydroxyquinol, the proposed intermediate of 2,4,6-trichloro-and 2,6-dichlorophenol degradation, and a second dioxygenase in the cleavage of hydroxyquinol, the proposed intermediate of 2,4-dichloro-and 2-chlorophenol degradation ( Fig.…”