Microbial degradation of chloroaromatics: use of the meta-cleavage pathway for mineralization of chlorobenzene.
Pseudomonas putida GJ31 is able to simultaneously grow on toluene and chlorobenzene. When cultures of this strain were inhibited with 3-fluorocatechol while growing on toluene or chlorobenzene, 3-methylcatechol or 3-chlorocatechol, respectively, accumulated in the medium. To establish the catabolic routes for these catechols, activities of enzymes of the (modified) ortho- and meta-cleavage pathways were measured in crude extracts of cells of P. putida GJ31 grown on various aromatic substrates, including chlorobenzene. The enzymes of the modified ortho-cleavage pathway were never present, while the enzymes of the meta-cleavage pathway were detected in all cultures. This indicated that chloroaromatics and methylaromatics are both converted via the meta-cleavage pathway. Meta cleavage of 3-chlorocatechol usually leads to the formation of a reactive acylchloride, which inactivates the catechol 2,3-dioxygenase and blocks further degradation of catechols. However, partially purified catechol 2,3-dioxygenase of P. putida GJ31 converted 3-chlorocatechol to 2-hydroxy-cis,cis-muconic acid. Apparently, P. putida GJ31 has a meta-cleavage enzyme which is resistant to inactivation by the acylchloride, providing this strain with the exceptional ability to degrade both toluene and chlorobenzene via the meta-cleavage pathway.
Mars
A E
AE
Department of Biochemistry, University of Groningen, The Netherlands.
Kasberg
T
T
Kaschabek
S R
SR
van Agteren
M H
MH
Janssen
D B
DB
Reineke
W
W
D001673:Biodegradation, Environmental; D050548:Catechol 1,2-Dioxygenase; D050557:Catechol 2,3-Dioxygenase; D002396:Catechols / Q000378:metabolism*; D002722:Chlorobenzenes / Q000378:metabolism*; D049308:Dioxygenases; D010105:Oxygenases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016958:Pseudomonas putida / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D014050:Toluene / Q000378:metabolism
D002396:Catechols; D002722:Chlorobenzenes; C031137:3-chlorocatechol; D014050:Toluene; D010105:Oxygenases; D049308:Dioxygenases; D050548:Catechol 1,2-Dioxygenase; D050557:Catechol 2,3-Dioxygenase; C031294:chlorobenzene