title: Phytase activity and its regulation in a rhizospheric strain of Serratia plymuthica.
abstract: Serratia plymuthica strain IC1270 isolated from the rhizosphere, possessing antagonistic activity towards a wide range of plant-pathogenic fungi, is able to hydrolyze phytate. Phytase activity was found intracellularly, while no activity was detected in the culture liquid. Optimum activity was found at pH 4-5; it completely disappeared at pH > 7.0 and 2.5. Phytase production was practically absent in the exponential phase and reached a maximum in the late stationary phase. Mutations of genes grrA and grrS, encoding GacA/GacS-like 2-component global regulatory system, or in gene rpoS encoding the sigma factor RpoS subunit of RNA polymerase, led to a deficiency in phytase production. Introduction into mutants of the respective wild-type genes cloned into the wide-range plasmid pJFF224-NX under the control of the bacteriophage T4 gene 32 promoter complemented this deficiency. This is the first report implicating the GacA/GacS global regulators and RpoS factor in phytase production in bacteria.
authors.affiliation: Institute of Molecular Genetics, Russian Academy of Sciences, 123 182, Moscow, Russia.
authors.forename: E
authors.initials: E
authors.lastname: Shedova
authors.forename: V
authors.initials: V
authors.lastname: Lipasova
authors.forename: G
authors.initials: G
authors.lastname: Velikodvorskaya
authors.forename: M
authors.initials: M
authors.lastname: Ovadis
authors.forename: L
authors.initials: L
authors.lastname: Chernin
authors.forename: I
authors.initials: I
authors.lastname: Khmel
mesh_terms: D010832:6-Phytase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D018517:Plant Roots / Q000382:microbiology; D012705:Serratia / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D027843:Vitis / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; C091100:GacA protein, Bacteria; D012808:Sigma Factor; D010832:6-Phytase