A new family of the order Alteromonadales, Aegicerorhabdaceae fam. nov. with description of two novel species Aegicerorhabdus qinzhovensis gen. nov., sp. nov., and Gallaecimonas aegicerasi sp. nov

Abstract

Two aerobic, Gram-stain-negative, motile rods, catalase and oxidase-positive, designated strains GXIMD 04217 ^T and GXIMD 01310 ^T, were isolated from in situ cultivation in mangrove rhizosphere soil collected in Guangxi Province, China. Strain GXIMD 04217 ^T can grow at 0-12% NaCl (w/v, optimum 5-6%), pH 5-10 (6) and 15-45 °C (28-37 °C), while strain GXIMD 01310 ^T can grow at 0-10% NaCl (4-5%), pH 4-8 (5-7) and 15-45 °C (28-37 °C). Global alignment of 16S rRNA gene sequences indicated that strain GXIMD 04217 ^T shares 92.9% sequence identity to its closest neighbour Photobacterium lucens CAIM 1938 ^T, then 92.2% to Gallaecimonas pentaromativorans DSM 21945 ^T. While strain GXIMD 01310 ^T shared 97.0% sequence identity to its closest neighbour "Gallaecimonas mangrovi" MCCC1K03441^T, then 96.1% to Gallaecimonas xiamenensis MCCC1A01354^T. Phylogenetic analyses based on 16S rRNA gene sequences and whole-genome sequences indicated that strain GXIMD 01310 ^T form an independent lineage alongside the family Gallaecimonadaceae. Concurrently, strain GXIMD 04217 ^T formed a separated branch independent of the other family in the order Alteromonadales. The genome DNA G + C contents of GXIMD 04217 ^T and GXIMD 01310 ^T were 64.1 and 55.7%, respectively. Both strains shared the identical respiratory quinone ubiquinone-8. The major polar lipids of GXIMD 04217 ^T were phosphatidyl glycerol (PG), phosphatidylethanolamine (PE), diphosphatidyl glycerol (DPG), three unidentified aminophospholipids (APL), and five unidentified phospholipids (PL). While those of GXIMD 01310 ^T were PG, PE, DPG, two unidentified aminophospholipids, six unidentified phospholipids, and one unidentified lipid. The major cellular fatty acids for GXIMD 04217 ^T were C_16:1ω7c/C_16:1ω6c (10.7%), and C_18:1ω7c/C_18:1ω6c (14.3%), and those of strain GXIMD 01310 ^T were C_16:1 (25.4%) and C_16:1ω7c/C_16:1ω6c (26.3%). Based on above characteristics, strain GXIMD 01310 ^T was suggested to represent a new species in the genus Gallaecimonas, and then strain GXIMD 04217 ^T was suggested to a novel family in the order Alteromonadales, for which the name Gallaecimonas aegicerasi sp. nov., A. qinzhovensis gen. nov., sp. nov. and Aegicerorhabdaceae fam. nov., were proposed. The type strain for G. aegicerasi is GXIMD 01310 ^T (= MCCC 1K08986^T = KCTC 8390 ^T), and that for A. qinzhovensis is GXIMD 04217 ^T (= MCCC 1K08658^T = KCTC 8392 ^T). The Aegicerorhabdaceae contains Aegicerorhabdus, the type genus is Aegicerorhabdus.

Keywords: A. qinzhovensis; Aegicerorhabdaceae; G. aegicerasi; Pure culture.