Phaeocystidibacter luteus gen. nov., sp. nov., a member of the family Cryomorphaceae isolated from the marine alga Phaeocystis globosa, and emended description of Owenweeksia hongkongensis

Abstract

A taxonomic study was carried out on strain PG2S01(T), isolated from a culture of Phaeocystis globosa, a haemolytic, toxin-producing, harmful marine alga. Cells of strain PG2S01(T) were Gram-negative, strictly aerobic, non-motile, non-fermentative, orange-pigmented, moderately halophilic rods. Growth was observed in the presence of 0.25-7.5 % NaCl and at 10-40 °C. The dominant fatty acids were iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C17 : 0 3-OH, iso-C16 : 0 3-OH, iso-C15 : 1 G and iso-C15 : 0 3-OH. The major polar lipids were phosphatidylethanolamine and several unidentified aminolipids, phospholipids and other lipids. The G+C content of the chromosomal DNA was 44.6 mol%. 16S rRNA gene sequence comparison showed that strain PG2S01(T) was most closely related to Owenweeksia hongkongensis UST20020801(T) (88.9 % 16S rRNA gene sequence similarity); levels of similarity between strain PG2S01(T) and the type strains of recognized representatives of genera in the family Cryomorphaceae were <88 %. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain PG2S01(T) formed a distinct evolutionary lineage within the family Cryomorphaceae. Strain PG2S01(T) was distinguishable from members of phylogenetically related genera by differences in several phenotypic properties. On the basis of phenotypic data and phylogenetic inference, strain PG2S01(T) represents a novel species in a new genus in the family Cryomorphaceae, for which the name Phaeocystidibacter luteus gen. nov., sp. nov. is proposed. The type strain of the type species is PG2S01(T) ( = CCTCC AB 209288(T) = LMG 25704(T) = MCCC 1F01079(T)). An emended description of O. hongkongensis Lau et al. 2005 is also proposed.