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

A marine bacterium producing protease inhibitors was isolated from neritic sea water and was studied phenotypically, genotypically and phylogenetically. This bacterium (strain B-10-31T) 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-10-31T 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 °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-α-alanine and l-glutamate, as the sole energy source. Ubiquinone-8 was the major respiratory quinone. The major fatty acids were C16 : 0, C16 : 1 ω7c, C16 : 1 ω9c and C18 : 1 ω7c. The G+C content of the DNA of strain B-10-31T was 42·0 mol%. Phylogenetic analysis, based on 16S rDNA sequences, showed that the strain clustered in the γ-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 γ-Proteobacteria cluster showed low levels of sequence similarity with strain B-10-31T (<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-10-31T=JCM 11461T=DSM 14643T) is proposed.