Involvement of an Extracellular Protease in Algicidal Activity of the Marine Bacterium Pseudoalteromonas sp. Strain A28

• DOI: 10.1128/aem.66.10.4334-4339.2000
• Publication Date: 2002-07-27T09:55:30Z
• Authors: Sun-og Lee; Junichi Kato; Noboru Takiguchi; Akio Kuroda; Tsukasa Ikeda; Atsushi Mitsutani; Hisao Ohtake
• Keywords: Pseudoalteromonas; Antipain; Diisopropyl fluorophosphate; Strain (injury); Molecular mass

ABSTRACT The marine bacterium Pseudoalteromonas sp. strain A28 was able to kill the diatom Skeletonema costatum NIES-324. culture supernatant of showed potent algicidal activity when it applied a paper disk placed on lawn S. condensed supernatant, which prepared by subjecting ultrafiltration with 10,000- M w -cutoff membrane, activity, suggesting that produced extracellular substances capable killing cells. then found have protease and DNase activities. Two mutants lacking designated NH1 NH2, were selected after N -methyl- ′-nitrosoguanidine mutagenesis. supernatants NH2 less than 15% detected parental strain, A28. purified homogeneity from using ion-exchange chromatography followed preparative gel electrophoresis. Paper-disk assays revealed had activity. molecular mass for 50 kDa, N-terminal amino acid sequence determined be Ala-Thr-Pro-Asn-Asp-Pro. optimum pH temperature 8.8 30°C, respectively, succinyl-Ala-Ala-Pro-Phe- p -nitroanilide as substrate. strongly inhibited phenylmethylsulfonyl fluoride, diisopropyl fluorophosphate, antipain, chymostatin, leupeptin. No significant inhibition EDTA, EGTA, phenanthroline or tetraethylenepentamine. These results suggest an serine responsible this bacterium.