title: Biodegradation of thifensulfuron-methyl by Ochrobactrum sp. in liquid medium and soil.
abstract: OBJECTIVE
  Excessive use of thifensulfuron-methyl has raised concerns for environmental contamination and phytotoxicity to crops. Experiments were performed to isolate a microorganism that can degrade thifensulfuron-methyl and assess its effectiveness.
  
  
  RESULTS
  A bacterial isolate, Ochrobactrum sp. ZWS16, capable of degrading thifensulfuron-methyl was studied. The half-life for thifensulfuron-methyl was less than 6 days in liquid medium after addition ZWS16 (5-400 mg thifensulfuron-methyl/l). Maximum biodegradation was 99.5 % for 50 mg thifensulfuron-methyl/l at 40 °C over 10 days. Of the five metabolites from the degradation of thifensulfuron-methyl that were identified, methyl 3-(N-carbamoylsulfamoyl) thiophene-2-carboxylate and 3-[(formimidoylamino-hydroxy-methyl)-sulfamoyl)-thiophene-2-carboxylic acid are reported for the first time. The degradation pathways might proceed via cleavage of the sulfonylurea bridge, O-demethylation, de-esterification and cleavage of the triazine ring. The removal of thifensulfuron-methyl was 58 % after inoculation of strain ZWS16 into sterilized soil. Strain ZWS16 can also degrade nicosulfuron, tribenuron-methyl, pyrazosulfuron-ethyl, metsulfuron-methyl and triasulfuron.
  
  
  CONCLUSIONS
  Addition of strain ZWS16 to both liquid medium and sterilized soil accelerated the degradation of thifensulfuron-methyl. Strain ZWS16 might therefore be useful in removing thifensulfuron-methyl contamination in water and soil.
authors.affiliation: College of Science, China Agricultural University, Beijing, 100193, China.
authors.forename: Weisong
authors.initials: W
authors.lastname: Zhao
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.forename: Dongzhi
authors.initials: D
authors.lastname: Li
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Li
authors.forename: Chengju
authors.initials: C
authors.lastname: Wang
authors.forename: Mingqi
authors.initials: M
authors.lastname: Zheng
authors.forename: Canping
authors.initials: C
authors.lastname: Pan
authors.forename: Lihong
authors.initials: L
authors.lastname: Qiu
mesh_terms: D001673:Biodegradation, Environmental; D042041:Ochrobactrum / Q000378:metabolism*; D010573:Pesticide Residues / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D013453:Sulfonylurea Compounds / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D013876:Thiophenes / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*
chemical_list: D010573:Pesticide Residues; D012989:Soil Pollutants; D013453:Sulfonylurea Compounds; D013876:Thiophenes; C414314:thifensulfuron methyl