title: Identification and characterization of a chitinase of Stenotrophomonas maltophilia, a bacterium that is antagonistic towards fungal phytopathogens.
abstract: A rhizosphere strain of Stenotrophomonas maltophilia strain MUJ that is strongly antagonistic towards fungal phytopathogens secretes to the culture medium a single form of active chitinolytic enzyme belonging to family 18 of glycosyl hydrolases. The chitinase was purified by a two-stage procedure embracing fractionation with ammonium sulfate and affinity chromatography. The molecular mass of the purified enzyme determined by SDS-PAGE was approximately 52 kDa. The enzyme demonstrated highest activity at 45°C and pH 6.8. The enzymatic protein showed considerable thermal stability during 2 h incubation at 45°C. The activity of the enzyme was strongly inhibited in the presence of Hg²⁺ and Cu²⁺. By applying mass spectrometry analysis, the peptides derived from the purified chitinase were assigned to amino acid sequences of the type ChiA chitinases synthesized by Stenotrophomonas bacteria. The purified enzyme inhibited the growth of fungal phytopathogens belonging to the genera Fusarium, Rhizoctonia and Alternaria.
authors.affiliation: Department of Biochemistry, Warsaw University of Life Sciences, SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland. urszula_jankiewicz@sggw.pl
authors.forename: Urszula
authors.initials: U
authors.lastname: Jankiewicz
authors.forename: Maria Swiontek
authors.initials: MS
authors.lastname: Brzezinska
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Saks
mesh_terms: D000595:Amino Acid Sequence; D000898:Antibiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002686:Chitin / Q000378:metabolism; D002688:Chitinases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D005658:Fungi / Q000254:growth & development; D008969:Molecular Sequence Data; D008970:Molecular Weight; D020615:Stenotrophomonas maltophilia / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D002686:Chitin; D002688:Chitinases