Pseudoalteromonas peptidolytica sp nov., a novel marine mussel-thread-degrading bacterium isolated from the Sea of Japan

A new bacterial species belonging to the genus Pseudoalteromonas is describ ed on the basis of phenotypic characterization, and sequence analysis of it s 16S rRNA-coding and gyrase B (gyrB) genes, Ten strains, isolated from sea water of Yamato Island, Sea of Japan, were Gram-negative, yellow, motile, polarly flagellated. aerobic, rod-shaped eubacteria and had a G+C content o f 42 mol%. Analysis of the 16S rDNA sequence revealed a clear affiliation b etween these strains and members of the gamma-Proteobacteria. High similari ty values were found with members of the genus Pseudoalteromonas and this w as supported by fatty acid profiles, The 16S rDNA sequence similarity betwe en strain F12-50-A1(T) and Pseudoalteromonas piscicida was very high (99.1% ). However, molecular characterizations employing small subunit 16S rDNA se quences were at the limits of resolution for the differentiation of species in this genus. As a result, DNA-DNA hybridization and sequence analyses of a more rapidly evolving gyrB gene were performed, Our assertion that this strain represents a distinct bacterial species within the genus Pseudoalter omonas was supported by both of these molecular analyses, Species-specific PCR probes were designed for the gyrB gene and used for the rapid screening of F12-50-A1(T)-like strains. thereby confirming the species, As these str ains cleave complex protein compounds of the Mytilus edulis foot by secreti ng proteases, the name Pseudoalteromonas peptidolytica sp, nov. is proposed , with strain F12-50-A1T (= MBICC F1250A1(T)) as the type strain.