Pseudaeromonas paramecii sp. nov., isolated from the ciliate Paramecium caudatum and emendation of the genus Pseudaeromonas.

A Gram-stain-negative, oxidase-negative and catalase-negative, motile, rod-shaped bacterial strain, designated PCS8T , hosted by the ciliate Paramecium caudatum was investigated by using a polyphasic approach. Strain PCS8T was observed to be able to grow at 12-44 °C (optimum, 36-37 °C), at pH 6.0-10.0 (optimum, 7.0) and in the presence of 0-3 % NaCl (optimum, 1-2 %). It could hydrolyse starch and aesculin and produce acid from d-sorbitol, myo-inositol, glycerol and l-rhamnose. The sequence similarity of the new isolate was 96.9 % with respect to Pseudaeromonas pectinilytica and 96.3 % with respect to Pseudaeromonas sharmana. Phylogenetically, strain PCS8T falls within the cluster comprising the Pseudaeromonas species. The predominant cellular fatty acids of strain PCS8T were C16 : 0 (35.8 %), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c; 35.1 %) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 10.8 %). This novel strain also contained various fatty acids that are not detected in other members of the genus Pseudaeromonas, such as C16 : 0 3-OH, C18 : 1ω9c and summed feature 5 (C18 : 2ω6,9c and/or C18 : 0 ante). Strain PCS8T contained ubiquinone-8 as the sole respiratory quinone and phosphatidylethanolamine and phosphatidylglycerol as major polar lipids. The G+C content of the genomic DNA of the type strain was 66.5 mol%. Based on the distinct phenotypic, phylogenetic, chemotaxonomic and G+C content results, strain PCS8T represents a currently undescribed species within the genus Pseudaeromonas in the family Aeromonadaceae, for which we suggest the name Pseudaeromonas paramecii sp. nov. with the type strain PCS8T (=KCTC 62038T =JCM 32226T ). An emended description of the genus Pseudaeromonas is also provided.