title: Production of the enzyme dihydrofolate reductase by methotrexate-resistant bacteria isolated from soil.
abstract: Six bacterial cultures isolated from soil were capable of growing in the presence of methotrexate (MTX). Two strains, PFR-1 and 3, developed resistance to 500 micrograms cm-3 MTX in the medium and produced elevated levels of the enzyme dihydrofolate reductase (EC 1.5.1.3): 2580 and 2702 U dm-3 compared to the sensitive parent strains (28 and 35 U dm-3). Isolate PFR-3 showed maximum enzyme production (4950 U dm-3, specific activity 12.56 U mg-1 in flasks and 5737 U dm-3, specific activity 14.80 U mg-1 in 5-dm3 fermenter) during exponential phase of growth (6 h) at 37 degrees C and pH 7.0.
authors.affiliation: Department of Biological and Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK.
authors.forename: P
authors.initials: P
authors.lastname: Nigam
authors.forename: R
authors.initials: R
authors.lastname: Marchant
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development / Q000302:isolation & purification; D008727:Methotrexate / Q000494:pharmacology*; D009584:Nitrogen / Q000494:pharmacology; D012988:Soil Microbiology; D013210:Staphylococcus / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development / Q000302:isolation & purification; D013696:Temperature; D013762:Tetrahydrofolate Dehydrogenase / Q000096:biosynthesis*
chemical_list: D003470:Culture Media; D013762:Tetrahydrofolate Dehydrogenase; D009584:Nitrogen; D008727:Methotrexate