Pseudoalteromonas sagamiensis sp. nov., a marine bacterium that produces protease inhibitors

Abstract

A marine bacterium producing protease inhibitors was isolated from neritic sea water and was studied phenotypically, genotypically and phylogenetically. This bacterium (strain B-10-31(T)) produced three types of protease inhibitor, namely, marinostatin, monastatin and leupeptin, which were considerably different in terms of their chemical structure and properties. Strain B-10-31(T) was a rod-shaped, non-spore-forming, Gram-negative, strictly aerobic bacterium that was motile by means of one polar flagellum. The strain required Na(+) for growth and exhibited optimal growth at 27 degrees C, pH 8.0 and 2 % (w/v) NaCl. It utilized various substrates, such as D-glucose, maltose, maltotriose, N-acetylglucosamine, L-threonine, L-serine, L-arginine, L-proline, L-alpha-alanine and L-glutamate, as the sole energy source. Ubiquinone-8 was the major respiratory quinone. The major fatty acids were C(16 : 0), C(16 : 1) omega7c, C(16 : 1) omega9c and C(18 : 1) omega7c. The G+C content of the DNA of strain B-10-31(T) was 42.0 mol%. Phylogenetic analysis, based on 16S rDNA sequences, showed that the strain clustered in the gamma-Proteobacteria. The aerobic marine bacterium Pseudoalteromonas bacteriolytica was the species most closely related to the new isolate (90.4 % 16S rDNA sequence similarity); other described species in the gamma-Proteobacteria cluster showed low levels of sequence similarity with strain B-10-31(T) (<90 %). Based on the above results, it is proposed that the novel marine bacterium should be classified as a new species, for which the name Pseudoalteromonas sagamiensis (type strain B-10-31(T)=JCM 11461(T)=DSM 14643(T)) is proposed.