title: Degradation of toluene by ortho cleavage enzymes in Burkholderia fungorum FLU100.
abstract: Burkholderia fungorum FLU100 simultaneously oxidized any mixture of toluene, benzene and mono-halogen benzenes to (3-substituted) catechols with a selectivity of nearly 100%. Further metabolism occurred via enzymes of ortho cleavage pathways with complete mineralization. During the transformation of 3-methylcatechol, 4-carboxymethyl-2-methylbut-2-en-4-olide (2-methyl-2-enelactone, 2-ML) accumulated transiently, being further mineralized only after a lag phase of 2 h in case of cells pre-grown on benzene or mono-halogen benzenes. No lag phase, however, occurred after growth on toluene. Cultures inhibited by chloramphenicol after growth on benzene or mono-halogen benzenes were unable to metabolize 2-ML supplied externally, even after prolonged incubation. A control culture grown with toluene did not show any lag phase and used 2-ML as a substrate. This means that 2-ML is an intermediate of toluene degradation and converted by specific enzymes. The conversion of 4-methylcatechol as a very minor by-product of toluene degradation in strain FLU100 resulted in the accumulation of 4-carboxymethyl-4-methylbut-2-en-4-olide (4-methyl-2-enelactone, 4-ML) as a dead-end product, excluding its nature as a possible intermediate. Thus, 3-methylcyclohexa-3,5-diene-1,2-diol, 3-methylcatechol, 2-methyl muconate and 2-ML were identified as central intermediates of productive ortho cleavage pathways for toluene metabolism in B. fungorum FLU100.
authors.affiliation: Department of Biological Waste Air Purification, Institute of Sanitary Engineering, Water Quality and Solid Waste Management, University of Stuttgart, Bandtäle 2, Stuttgart, D-70569, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Dobslaw
authors.forename: Karl-Heinrich
authors.initials: KH
authors.lastname: Engesser
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019117:Burkholderia / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D012989:Soil Pollutants / Q000378:metabolism; D014050:Toluene / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012989:Soil Pollutants; D014050:Toluene