Thioclava kandeliae sp. nov., Isolated from the Rhizosphere Soil of Mangrove Plant Kandelia candel.

Abstract

A Gram-stain-negative, non-motile, aerobic bacterium, designated as strain CPCC 100088^T, was isolated from a rhizosphere soil sample of Kandelia candel in a mangrove. Growth of strain CPCC 100088^T was observed at 15-37 °C, pH 6.0-9.0, and in the presence of 0-7% (w/v) NaCl with optimal growth at 28-32 °C, pH 6.0-7.0 and in the absence of NaCl. This strain was positive for catalase and oxidase activity. The major respiratory quinone was Q-10. Phosphatidylethanolamine and phosphatidylglycerol were the predominant polar lipids. The major fatty acids were C_16:0 and summed feature 8 (C_18:1ω7c/C_18:1ω6c). Strain CPCC 100088^T shared the highest 16S rRNA gene sequence similarity (96.4%) with Thioclava pacifica DSM 10166^T and Thioclava marina 11.10-0-13^T, followed by 95.5-95.8% with other members of the genus Thioclava. In the phylogenetic trees reconstructed using 16S rRNA gene or based on the whole genomes, strain CPCC 100088^T was within the Thioclava phylogenetic clade within the family Paracoccaceae. The whole-genome of strain CPCC 100088^T consisted of 4.3 Mbp with the G + C content of 61.3%. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values (19.6% and 74.4%) based on whole-genome sequences of strain CPCC 100088^T and its closest phylogenetic neighbour species were below the threshold for species delineation. Based on the phenotypic and genotypic data, we propose that strain CPCC 100088^T represents a novel species of the genus Thioclava, for which the name Thioclava kandeliae sp. nov. is proposed, with CPCC 100088^T (= I07B-00821^T = KCTC 32191^T) as the type strain.