title: Klebsiella planticola strain DSZ mineralizes simazine: physiological adaptations involved in the process.
abstract: We examined the ability of a soil bacterium, Klebsiella planticola strain DSZ, to degrade the herbicide simazine (SZ). Strain DSZ is metabolically diverse and grows on a wide range of s-triazine and aromatic compounds. DSZ cells grown in liquid medium with SZ (in 10 mM ethanol) as carbon source mineralized 71.6+/-1.3% of 0.025 mM SZ with a yield of 4.6+/-0.3 microg cell dry weight mmol(-1) carbon. The metabolites produced by DSZ during SZ degradation included ammeline, cyanuric acid, N-formylurea and urea. We studied the physiological adaptations which allow strain DSZ to metabolize SZ. Using scanning electron microscopy, we detected DSZ cells covering the surfaces of SZ crystals when the herbicide was used at high concentrations (0.1 mM). The membrane order observed by FTIR spectroscopy showed membrane activity at low temperature (4 degrees C) to assimilate the herbicide. Membrane fatty acid analysis demonstrated that strain DSZ adapted to grow on SZ by increasing the degree of saturation of membrane lipid fatty acid; and the opposite effect was detected when both SZ and ethanol were used as carbon sources. This confirms the modulator effect of ethanol on membrane fluidity.
authors.affiliation: Departamento de Bioquímica y Biología Molecular IV, Universidad Complutense, Madrid, Spain.
authors.forename: Mariela
authors.initials: M
authors.lastname: Sánchez
authors.forename: Carlos
authors.initials: C
authors.lastname: Garbi
authors.forename: Roberto
authors.initials: R
authors.lastname: Martínez-Alvarez
authors.forename: Luis T
authors.initials: LT
authors.lastname: Ortiz
authors.forename: José Luis
authors.initials: JL
authors.lastname: Allende
authors.forename: Margarita
authors.initials: M
authors.lastname: Martín
mesh_terms: D000222:Adaptation, Physiological; D001673:Biodegradation, Environmental; D002462:Cell Membrane / Q000378:metabolism; D003080:Cold Temperature; D000431:Ethanol / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D006540:Herbicides / Q000378:metabolism; D007709:Klebsiella / Q000145:classification / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D008903:Minerals / Q000378:metabolism*; D012839:Simazine / Q000378:metabolism*; D012989:Soil Pollutants / Q000378:metabolism* / Q000633:toxicity; D013696:Temperature
chemical_list: D005227:Fatty Acids; D006540:Herbicides; D008903:Minerals; D012989:Soil Pollutants; D000431:Ethanol; D012839:Simazine