Pseudofrancisella aestuarii gen. nov., sp. nov., a novel member of the family Francisellaceae isolated from estuarine seawater.

A Gram-negative, aerobic, non-motile and non-spore forming bacterium, designated strain SYSU WZ-2, was isolated from an estuarine seawater sample. Growth of strain SYSU WZ-2 was observed at temperature range of 10-40° C (optimum, 32 °C), pH range of 6-10 (optimum, pH 7-8) and in the presence of up to 5.0% NaCl (w/v). The DNA G+C content of the novel strain was determined to be 30.1% (genome). The major polar lipids were found to be diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, an unidentified aminolipid, two unidentified aminophospholipids and two unidentified phospholipids. The major fatty acids were C 3-OH (27.5%), Cω9c (19.3%), C (17.0%) and C (12.9%). The respiratory quinone was found to be ubiquinone Q8. Pairwise comparison of the 16S rRNA gene sequence showed that strain SYSU WZ-2 shares high identities with members of the genera Francisella (94.8-95.9%) and Allofrancisella (93.8-94.2%). The phylogenetic dendrograms based on 16S rRNA gene sequences with the members of the family Francisellaceae showed that the strain SYSU WZ-2 formed a distinct phylogenetic lineage well separated from the members of the genera Francisella and Allofrancisella. MALDI-TOF mass spectrometric analysis also depicted a different profile for strain SYSU WZ-2 compared with those of members of the genera Francisella and Allofrancisella. Based on the above results and differences in phenotypic and chemotaxonomic features, strain SYSU WZ-2 is characterized to represent a new species of a novel genus, for which the name Pseudofrancisella aestuarii gen. nov., sp. nov. is proposed (type strain SYSU WZ-2 = KCTC 52557 = CGMCC 1.13718).