Pseudoalteromonas spongiae sp. nov., a novel member of the γ-Proteobacteria isolated from the sponge Mycale adhaerens in Hong Kong waters

A Gram-negative, non-spore-forming, short rod-shaped bacterium (UST010723-006(T)) was isolated from the surface of the sponge Mycale adhaerens in Hong Kong waters. Cells of UST010723-006(T) did not have flagella and were non-motile. Colonies were pale orange in colour, 2-4 mm in diameter, convex with a smooth surface and an entire translucent margin. Gas bubbles were observed in the colonies and also in the agar matrix underneath and adjacent to the colonies. UST010723-006(T) was heterotrophic, strictly aerobic and required NaCl for growth (2.0-6.0%). It grew at pH 5.0-10.0 and between 12 and 44 degrees C. Phylogenetic analysis of the 16S rRNA gene sequence placed UST010723-006(T) within the genus Pseudoalteromonas of the gamma-subclass of the Proteobacteria. The DNA G+C content is 40.6 mol% and the dominant fatty acids were 12:0 3-OH, 14:0, 15:0 iso 2-OH, 16:0, 16:1omega7, 17:1omega8 and 18:1omega7 (altogether representing 75.9% of the total). These data supported the affiliation of UST010723-006(T) to the genus Pseudoalteromonas. The closest relatives were Pseudoalteromonas luteviolacea, P. phenolica, P. rubra and P. ruthenica with similarity values ranging from 95.4 to 96.8%. UST010723-006(T) differed from these closest relatives by 9-19 traits. Molecular evidence, together with phenotypic characteristics, suggests that UST010723-006(T) constitutes a novel species within the genus Pseudoalteromonas. The name Pseudoalteromonas spongiae sp. nov. is proposed for this bacterium. The type strain is UST010723-006(T) (=NRRL B-41100(T)=JCM 12884(T)).