Roseovarius conchicola sp. nov. and Aliiroseovarius conchicola sp. nov., isolated from the marine conch Reishia bronni.

Abstract

The intertidal zone is an area located between the marine environment and the terrestrial environment and is exposed to various stresses. To investigate the mutualistic relationship between hosts and symbiotic micro-organisms inhabiting the intertidal zone, strains 2305UL8-3^T and 2305UL8-7^T were isolated from Reishia bronni, a species living in the intertidal zone of Ulleungdo Island, South Korea. Both strains are Gram-stain-negative, catalase- and oxidase-positive and facultatively anaerobic. Strains 2305UL8-3^T and 2305UL8-7^T grow optimally at 30.0 °C and 28.0-30.0 °C, respectively, under conditions of pH 8.0 and 3.0 % (w/v) NaCl. They have Q-10 as the primary quinone, and their common main fatty acids are C_16:0 and summed feature 8 (C_18:1 ω7c and/or C_18:1 ω6c). Additionally, their primary polar lipids include phosphatidylcholine and phosphatidylglycerol. The two novel strains have an arsenic reduction pathway that reduces the oxidation state of arsenic and are expected to influence environmental regulation processes through the catabolic sulphate reduction system. Based on these characteristics, they exhibit resistance potential to environmental stresses, specifically arsenic exposure in the intertidal zone, where arsenic contamination is often associated with pollution and tidal fluctuations. Analysing the 16S rRNA gene sequence similarity, strain 2305UL8-3^T shared 96.60 % similarity with Roseovarius faecimaris MME-070^T, while strain 2305UL8-7^T showed 98.13 % similarity with Aliiroseovarius sediminilitoris M-M10^T. Polyphasic analysis revealed that strains 2305UL8-3^T and 2305UL8-7^T should be identified as novel species within the genera Roseovarius and Aliiroseovarius, respectively. Therefore, Roseovarius conchicola sp. nov. with the type strain 2305UL8-3^T (=KCTC 8475^T=MCCC 1K09523^T=JCM 37202^T) and Aliiroseovarius conchicola sp. nov. with the type strain 2305UL8-7^T (=KCTC 8476^T=MCCC 1K09524^T=JCM 37203^T) are proposed.