Four marine heterotrophic, aerobic, pink-pigmented and non-motile bacterial strains were isolated from sea water and algae collected in the Sea of Japan. In a polyphasic taxonomic study, 16S rRNA gene sequence analysis indicated that the strains were phylogenetically highly related to Algoriphagus ratkowskyi LMG 21435T, a member of the phylum Bacteroidetes. Further phenotypic, chemotaxonomic and genomic analyses revealed that the strains represent three novel species of the genus Algoriphagus, for which the following names are proposed: Algoriphagus aquimarinus sp. nov., Algoriphagus chordae sp. nov. and Algoriphagus winogradskyi sp. nov., with type strains KMM 3958T (=LMG 21971T=CCUG 47101T), KMM 3957T (=LMG 21970T=CCUG 47095T) and KMM 3956T (=LMG 21969T=CCUG 47094T), respectively. The species Hongiella halophila Yi and Chun 2004 is transferred to the genus Algoriphagus as Algoriphagus halophilus comb. nov. because of its close phylogenetic relatedness to Algoriphagus species and analogous phenotypic and chemotaxonomic properties. The above-mentioned novel species descriptions and species reclassification justify emended descriptions of the genera Algoriphagus and Hongiella.

Three novel heterotrophic, Gram-negative, yellow-pigmented, aerobic, gliding, oxidase- and catalase-positive bacteria were isolated from algae collected in the Gulf of Peter the Great, Sea of Japan. 16S rRNA gene sequence analysis revealed that the strains studied represented members of the familyFlavobacteriaceaeand showed 93·5–93·8 % similarity with their closest relative,Psychroserpens burtonensis. The DNA G+C content of the strains was 34–37 mol%. The major respiratory quinone was MK-6. The predominant fatty acids were iso-C_15 : 0, anteiso-C_15 : 0, iso-C_15 : 1, iso-C_16 : 0-3OH and iso-C_17 : 0-3OH. On the basis of their phenotypic, chemotaxonomic, genotypic and phylogenetic characteristics, the newly described bacteria have been assigned to the new genusWinogradskyellagen. nov., asWinogradskyella thalassocolasp. nov. (type strain, KMM 3907^T=KCTC 12221^T=LMG 22492^T=DSM 15363^T),Winogradskyella epiphyticasp. nov. (type strain, KMM 3906^T=KCTC 12220^T=LMG 22491^T=CCUG 47091^T) andWinogradskyella eximiasp. nov. (type strain, KMM 3944^T(=KCTC 12219^T=LMG 22474^T).

Three strains of the marine, gliding, pigmented, facultatively anaerobic, heterotrophic, Gram-negative bacteria were isolated from the green algaeAcrosiphonia sonderi(Kütz) Kornm andUlva fenestrataRuprecht inhabiting the Sea of Japan. 16S rDNA sequence analysis indicated that the strains were members of the familyFlavobacteriaceae, in which they occupied separate lineages. The predominant cellular fatty acids were i15 : 0, a15 : 0, i15 : 1, 15 : 0, 15 : 1ω6c, i15 : 0 3-OH and i17 : 0 3-OH. The DNA base compositions were 31–33 mol% G+C. Based on the phenotypic, genotypic, chemotaxonomic and phylogenetic analyses, the novel bacteria should be placed in a novel taxon asAlgibacter lectusgen. nov., sp. nov. with type strain KMM 3902^T(=KCTC 12103^T=DSM 15365^T).

The taxonomic position of four heterotrophic, aerobic, Gram-negative, non-motile and moderately halophilic marine bacteria, isolated from the green alga Acrosiphonia sonderi (Kütz) Kornm, was established. 16S rDNA sequence analysis indicated that the strains studied are members of the family Flavobacteriaceae, in which they form a distinct lineage. On the basis of phenotypic, chemotaxonomic, genotypic and phylogenetic data, the novel bacteria were classified as Mesonia algae gen. nov., sp. nov. The type strain is KMM 3909^T (=KCTC 12089^T=CCUG 47092^T).

Two marine, heterotrophic, aerobic, yellow-pigmented, agarolytic bacterial strains that are motile by means of gliding were isolated from the green alga Acrosiphonia sonderi and from sea water. Comparative 16S rRNA gene sequence analysis revealed an affiliation between the strains studied and the genus Formosa, a member of the family Flavobacteriaceae. The level of sequence similarity between strain KMM 3901^T and Formosa algae KMM 3553^T was 99·1 %. The results of DNA–DNA hybridization experiments and phenotypic analysis indicated that the strains represent a novel species of the genus Formosa, for which the name Formosa agariphila sp. nov. is proposed, with KMM 3901^T (=KCTC 12365^T=LMG 23005^T=DSM 15362^T) as the type strain. The description of the genus Formosa is emended with newly obtained data.

A Gram-negative, facultatively anaerobic, slightly halophilic bacterium that was motile by gliding, designated KMM 6390^T, was isolated from the coastal green alga Ulva fenestrata collected from the Sea of Japan. A comparative analysis of 16S rRNA gene sequences revealed that strain KMM 6390^T was a member of the genus Winogradskyella , with Winogradskyella echinorum KMM 6211^T as its closest relative (97.8 % 16S rRNA gene sequence similarity). 16S rRNA gene sequence similarities between the isolate and other members of the genus Winogradskyella were 95.4–96.7 %. DNA–DNA relatedness between the isolate and W. echinorum KMM 6211^T was 27 %. Strain KMM 6390^T was able to grow with 0.5–4.0 % NaCl and at 4–37 °C. The isolate decomposed casein, gelatin, starch and DNA and produced acid from galactose, d-glucose, lactose and maltose. The major fatty acids were iso-C_15 : 0, iso-C_15 : 1, anteiso-C_15 : 0 and C_15 : 0. The polar lipid profile comprised phosphatidylethanolamine and two unknown aminolipids. The DNA G+C content was 34.2 mol%. On the basis of phylogenetic, chemotaxonomic and phenotypic investigations, strain KMM 6390^T represents a novel species of the genus Winogradskyella , for which the name Winogradskyella ulvae sp. nov. is proposed; the type strain is KMM 6390^T ( = KCTC 23626^T = LMG 26444^T). Emended descriptions of the genus Winogradskyella and of W. thalassocola , W. echinorum , W. exilis and W. eximia are also provided.