Actibacterium mucosum gen. nov., sp nov., a marine alphaproteobacterium from Mediterranean seawater

Strain R46(T), a marine alphaproteobacterium, was isolated from Mediterranean seawater at Malvarrosa beach, Valencia, Spain. It is an aerobic chemo-organotrophic, mesophilic and slightly halophilic organism, with complex ionic requirements. Phylogenetic analyses based on the 16S rRNA and gyrB gene sequences showed that strain R46(T) formed a separate branch within the family Rhodobacteraceae, bearing similarities below 94.7 and 80.3%, respectively, to any other recognized species. It contained 010 as the predominant isoprenoid quinone and C-18:1 omega 7C/C-18:1 omega 6c as the major cellular fatty acid. Phosphatidylglycerol was the only identified polar lipid, although other lipids were also detected. The DNA G+C content of the genomic DNA was 61.3 mol%. On the basis of extensive phenotypic and phylogenetic comparative analysis, it is concluded that the strain represents a novel genus and species, for which the name Actibacterium mucosum gen. nov., sp. nov. is proposed. The type strain of the type species is Actibacterium mucosum R46(T) (=CECT 7668(T)=KCTC 23349(T)).