Metabolism of 4-chloro-2-methylphenoxyacetate by a soil pseudomonad. Preliminary evidence for the metabolic pathway.
1. A pseudomonad capable of utilizing the herbicide 4-chloro-2-methylphenoxyacetate as a sole carbon source was isolated from soil and cultured in liquid medium. 2. Analysis of induction patterns of 4-chloro-2-methylphenoxyacetate-grown cells suggests that 5-chloro-o-cresol and 5-chloro-3-methylcatechol are early intermediates in the oxidation of 4-chloro-2-methylphenoxyacetate. Cells were not adapted to oxidize 4-chloro-6-hydroxy-2-methylphenoxyacetate. 3. In culture, 4-chloro-2-methylphenoxyacetate rapidly disappeared and the chlorine in the molecule was quantitatively released as Cl(-) ion. 4. A lactone (gamma-carboxymethylene-alpha-methyl-Delta(alphabeta)-butenolide) was isolated from cultures and established as an intermediate. 5. The following metabolic pathway is suggested: 4-chloro-2-methylphenoxyacetate --> 5-chloro-o-cresol --> 5-chloro-3-methylcatechol --> cis-cis-gamma-chloro-alpha-methylmuconate --> gamma-carboxymethylene-alpha-methyl-Delta(alphabeta)-butenolide --> gamma-hydroxy-alpha-methylmuconate. 6. The tentative identification of 5-chloro-o-cresol, a gamma-chloro-alpha-methylmuconate and gamma-hydroxy-alpha-methylmuconate in culture extracts supports this scheme. However, the catechol was never observed to accumulate in cultures. 7. The detection of 4-chloro-6-hydroxy-2-methylphenoxyacetate, 2-methyl-phenoxyacetate, a dehalogenated cresol and oxalate in culture extracts is discussed in relation to the proposed metabolic pathway.
D002396:Catechols / Q000378:metabolism; D002498:Centrifugation; D002712:Chlorides / Q000032:analysis; D002845:Chromatography; D003377:Countercurrent Distribution; D003408:Cresols / Q000378:metabolism; D003470:Culture Media; D006016:Glycolates / Q000378:metabolism*; D006540:Herbicides / Q000378:metabolism*; D007259:Infrared Rays; D007783:Lactones / Q000032:analysis; D008365:Manometry; D010070:Oxalates / Q000378:metabolism; D011549:Pseudomonas / Q000378:metabolism*; D012988:Soil Microbiology; D013053:Spectrophotometry; D013997:Time Factors; D014466:Ultraviolet Rays
D002396:Catechols; D002712:Chlorides; D003408:Cresols; D003470:Culture Media; D006016:Glycolates; D006540:Herbicides; D007783:Lactones; D010070:Oxalates