title: Characterization of a pyoverdine-deficient mutant of Pseudomonas fluorescens impaired in the secretion of extracellular lipase.
abstract: A mutant of Pseudomonas fluorescens strain B52 deficient in the synthesis of the fluorescent pigment, pyoverdine, was isolated. Absence of pyoverdine and other siderophores was confirmed by gel filtration, a specific siderophore assay, and inhibition studies with the iron chelator EDDA. Both parent and mutant synthesized additional outer membrane proteins in response to iron-limitation. Mutant cells cultured in the absence of iron(III) accumulated 55Fe-labeled pyoverdine. The mutant produced extracellular proteinase normally on various media, but was deficient in lipase secretion. Growth of the mutant with partially-purified pyoverdine resulted in a 2.5-fold stimulation of lipase secretion. The mutant grew poorly in deferrated medium; however, the addition of iron(III) stimulated growth. Proteinase secretion in deferrated medium was stimulated over a narrow range of iron(III) concentration, while lipase secretion was only slightly affected. The data suggest that separate regulatory mechanisms exist for the control of proteinase and lipase secretion by iron(III).
authors.affiliation: Departamento de Technología y Bioquímica de los Alimentos, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Fernandez
authors.forename: C
authors.initials: C
authors.lastname: San José
authors.forename: H
authors.initials: H
authors.lastname: Cholette
authors.forename: R C
authors.initials: RC
authors.lastname: McKellar
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D004492:Edetic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005110:Extracellular Space / Q000201:enzymology*; D005290:Ferric Compounds / Q000378:metabolism; D006131:Growth Inhibitors / Q000494:pharmacology; D008049:Lipase / Q000096:biosynthesis*; D009842:Oligopeptides; D010447:Peptide Hydrolases / Q000096:biosynthesis; D010860:Pigments, Biological / Q000172:deficiency* / Q000235:genetics / Q000302:isolation & purification; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000254:growth & development; D011551:Pseudomonas fluorescens / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
chemical_list: D005290:Ferric Compounds; D006131:Growth Inhibitors; D009842:Oligopeptides; D010860:Pigments, Biological; C026058:EDDA; C042453:pyoverdin; D004492:Edetic Acid; D008049:Lipase; D010447:Peptide Hydrolases