Demequina globuliformis sp. nov., Demequina oxidasica sp. nov. and Demequina aurantiaca sp. nov., actinobacteria isolated from marine environments, and proposal of Demequinaceae fam. nov. Harumi Ue, 1 Yoshihide Matsuo, 2 Hiroaki Kasai 3 and Akira Yokota 1 Correspondence Harumi Ue Harua@aol.jp 1 Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo 113-0032, Japan 2 Suntory Holdings Limited, R&D Planning Division, 1-1-1 Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka 618-8503, Japan 3 Marine Biosciences Kamaishi Research Laboratory, Kitasato University, 3-75-1, Heita, Kamaishi, Iwate 026-0001, Japan Three Gram-stain-positive actinobacterial strains, designated YM24-125 T , YM05-1041 T and YM12-102 T , were isolated from marine environments. Phylogenetic analysis based on 16S rRNA gene sequences indicated that they belonged to the suborder Micrococcineae and were most closely related to members of the genus Demequina with 95.0–98.4 % sequence similarities. Cells of strains YM05-1041 T and YM12-102 T were rod-shaped, similar to members of the genus Demequina, while cells of strain YM24-125 T were cocci to short ovoid rods. All strains grew in the absence of NaCl, but tolerated up to 15 % NaCl. The major menaquinone was demethylmenaquinone DMK-9 (H 4 ) and the major polar lipids were phosphatidylinositol, diphosphatidylglycerol and phosphatidyglycerol. All strains contained straight-chain, iso- branched and anteiso-branched saturated fatty acids. The DNA G+C contents were 65.3– 67.3 mol%. The peptidoglycans of strains YM05-1041 T and YM12-102 T were the A4b type with ornithine while that of strain YM24-125 T contained ornithine and lysine as diamino acids. Phylogenetic analyses and differences in physiological and biochemical characteristics indicated that these three isolates represent novel species within the genus Demequina, for which the names Demequina globuliformis sp. nov. (with YM24-125 T 5NBRC 106266 T 5KCTC 19747 T 5MBIC 08349 T as the type strain), Demequina oxidasica sp. nov. (with YM05-1041 T 5NBRC 106264 T 5KCTC 19746 T 5MBIC 08346 T as the type strain) and Demequina aurantiaca sp. nov. (with YM12-102 T 5NBRC 106265 T 5KCTC 19745 T 5MBIC 08347 T as the type strain) are proposed. Based on differences in the quinone system, the presence of demethylmenaquinone DMK-9(H 4 ) and the pattern of 16S rRNA signatures, the three novel strains and current members of the genus Demequina represent a unique family within the suborder Micrococcineae. Therefore, the family Demequinaceae fam. nov. is also proposed. The genus Demequina was proposed by Yi et al. (2007) and, at the time of writing, consists of three species: Demequina aestuarii JCM 12123 T , isolated from a tidal flat sediment (Yi et al., 2007), Demequina lutea DSM 19970 T , isolated from a permafrost soil (Finster et al., 2009) and Demequina salsine- moris DSM 22060 T , isolated from mangrove soil (Matsumoto et al., 2010). The genus Demequina is characterized by the presence of demethylmenaquinone in the quinone system and belongs to the family Cellulomonadaceae within the suborder Micrococcineae, order Actinomycetales of the sub- class Actinobacteridae (Zhi et al., 2009). Actinobacteria are considered treasure troves of bioactive secondary metabolites. However, the identities and divers- ity of actinobacteria in marine environments remain Abbreviations: ML, maximum likelihood; MP, maximum parsimony; NJ, neighbour-joining. The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences of strains YM24-125 T , YM05-1041 T and YM12-102 T are AB522643, AB522640 and AB522641, respectively. Two supplementary figures and four supplementary tables and a supplementary method are available with the online version of this paper. International Journal of Systematic and Evolutionary Microbiology (2011), 61, 1322–1329 DOI 10.1099/ijs.0.024299-0 1322 024299 G 2011 IUMS Printed in Great Britain