Microbulbifer litoralis sp. nov., Isolated from Seashore of Weizhou Island

Abstract

A bacterium designated GXH0434^T was isolated from sea shore samples collected from Weizhou Island, Beihai, Guangxi, China. The organism is motile, strictly aerobic, and possesses a rod-coccus cell cycle in association with the growth phase. It can grow at 15-45 °C (optimum 37 °C), at pH 6.0-11.0 (optimum 6.0), and at 0-20% (w/v) NaCl (optimum 5.0-8.0%). The strain is positive for peroxidase and oxidase activity, negative for Voges-Proskauer test, can hydrolyze Tween 20, Tween 60, Tween 80, casein, and is able to produce siderophore and has the function of nitrogen fixation. Molecular phylogenetic analysis based on 16S rRNA gene sequences indicated that GXH0434^T was most closely related to Microbulbifer halophilus KCTC 12848^T with the similarity of 97.2%, followed by Microbulbifer chitinilyticus JCM 16148^T (97.1%) and Microbulbifer taiwanensis LMG 26125^T (96.5%). The digital DNA-DNA hybridization and the average nucleotide identity values between GXH0434^T and Microbulbifer halophilus KCTC 12848^T were 28.90% and 83.38%, respectively, which were below thresholds of species delineation. The genomic DNA G+C content of the strain was 61.9%. The major fatty acids were iso-C_15:0, C_16:0, iso-C_11:0 3-OH, iso-C_11:0 and Summed features 8 (C_18:0 ω7c and/or C_18:0 ω6c). The major polar lipids detected in GXH0434^T were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylcholine (PC). The major respiratory quinone was ubiquinone Q-8. Based on the above polyphasic classification indicated strain GXH0434^T represents a novel species of the genus Microbulbifer, for which the name Microbulbifer litoralis sp. nov. is proposed. The type strain is GXH0434^T (= MCCC 1K07158^T = KCTC 92169^T).