Aurantimonas coralicida gen. nov., sp nov., the causative agent of white plague type II on Caribbean scleractinian corals

A bacterium previously isolated from a diseased colony of the scleractinian coral Dichocoenia stokesi (common name elliptical star coral) was subjected to a detailed polyphasic taxonomic characterization. The isolate, designated WP1(T), was halophilic and strictly aerobic and formed golden-orange-pigmented colonies after prolonged incubation. Cells of WP1T were Gram-negative, rod-shaped and showed a characteristic branching rod morphology. Chemotaxonomically, WP1(T) was characterized by having Q-10 as the major respiratory lipoquinone and sym-homospermidine as the main component of the cellular polyamine content. The predominant constituent in the cellular fatty acid profile was C(18:1)omega7c, along with C-19:0 cyclo omega8c and C-16:0. Other fatty acids present in smaller amounts were C-17:0, C-18:0, C(16:1)omega7c, C(20:1)omega7c and C-18:1 2-OH. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine. Minor amounts of diphosphatidylglycerol, phosphatidylmonomethylethanolamine and phosphatidyldimethylethanolamine were present. The G+C content of the genomic DNA was 66.3 mol%. Phylogenetic analysis of the 16S rRNA gene sequence showed that WP1(T) represents a separate subline of descent within the order 'Rhizobiales' of the 'Alphaproteobacteria'. The new line of descent falls within the group of families that includes the Rhizobiaceae, Bartonellaceae, Brucellaceae and 'Phyllobacteriaceae', with no particular relative within this group. The 16S rRNA gene sequence similarity to all established taxa within this group was not higher than 92.0% (to Mesorhizobium mediterraneum). To accommodate this emerging coral pathogen, the creation of a new genus and species is proposed, Aurantimonas coralicida gen. nov., sp. nov. (type strain WP1(T) = CIP 107386(T) = DSM 14790(T)).