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 T , was isolated from an estuarine seawater sample. Growth of strain SYSU WZ-2 T 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 18:0 3-OH (27.5%), C 18:1 ω 9c (19.3%), C 16:0 (17.0%) and C 14:0 (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 T 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 T 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 T 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 T 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 T = KCTC 52557 T = CGMCC 1.13718 T ).