Degradation of mono-chlorophenols by a mixed microbial community via a meta- cleavage pathway.
A mixed microbial community, specially designed to degrade a wide range of substituted aromatic compounds, was examined for its ability to degrade mono-chlorophenols as sole carbon source in aerobic batch cultures. The mixed culture degraded 2-, 3-, and 4-chlorophenol (1.56 mM) via a meta- cleavage pathway. During the degradation of 2- and 3-chlorophenol by the mixed culture, 3-chlorocatechol production was observed. Further metabolism was toxic to cells as it led to inactivation of the catechol 2,3-dioxygenase enzyme upon meta- cleavage of 3-chlorocatechol resulting in incomplete degradation. Inactivation of the meta- cleavage enzyme led to an accumulation of brown coloured polymers, which interfered with the measurement of cell growth using optical density. Degradation of 4-chlorophenol by the mixed culture led to an accumulation of 5-chloro-2-hydroxymuconic semialdehyde, the meta- cleavage product of 4-chlorocatechol. The accumulation of this compound did not interfere with the measurement of cell growth using optical density. 5-chloro-2-hydroxymuconic semialdehyde was further metabolized by the mixed culture with a stoichiometric release of chloride, indicating complete degradation of 4-chlorophenol by the mixed culture via a meta- cleavage pathway.
Farrell
A
A
School of Biotechnology, Dublin City University, Republic of Ireland.
Quilty
B
B
D000192:Actinomycetales / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002396:Catechols / Q000378:metabolism; D002733:Chlorophenols / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D011549:Pseudomonas / Q000254:growth & development / Q000378:metabolism*; D014242:Trichoderma / Q000254:growth & development / Q000378:metabolism*
D002396:Catechols; D002733:Chlorophenols; C031137:3-chlorocatechol; C038861:4-chlorocatechol; C030683:2-chlorophenol; C030682:3-chlorophenol