Seven psychrotolerant, Gram-negative bacterial strains, five dust- and airborne isolates (MA101bT, MA306a, MA405/90, MA-olkiT and NW12T) and two from the Antarctic (Ant 20 and M3C203B-B), were subjected to a polyphasic characterization to determine their taxonomic position. High 16S rDNA sequences similarities (99·3–100·0 %) demonstrated that they were closely related to each other. Phylogenetic evaluation of their 16S rDNA sequences revealed that they are members of the genus Sphingomonas sensu stricto, encompassing a separate branch within this genus. They shared 94·4–96·6 % 16S rDNA sequence similarity with species of this genus. All Sphingomonas-specific signature nucleotides were also detected. The presence of the major ubiquinone Q-10, sym-homospermidine as the predominant polyamine, Sphingomonadaceae-specific sphingoglycolipid in the polar lipid patterns and a fatty acid profile containing C14 : 0 2-OH and lacking 3-OH fatty acids were in agreement with identification of these strains as members of the genus Sphingomonas sensu stricto. Results from DNA–DNA hybridizations and comparison of protein patterns indicated that the seven strains are members of three distinct species. One species is represented by strains MA101bT, MA306a and MA405/90, the second by strains NW12T, Ant 20 and M3C203B-B and the third by one strain, MA-olkiT. Their distinction at the species level was also supported by results of biochemical characterization and partly supported by riboprints and genomic fingerprints. On the basis of these results, three novel species of the genus Sphingomonas are proposed: Sphingomonas aurantiaca sp. nov., consisting of strains MA101bT (=DSM 14748T=LMG 21377T), MA306a and MA405/90 (=DSM 14749=LMG 21378), Sphingomonas faeni sp. nov. MA-olkiT (=DSM 14747T=LMG 21379T) and Sphingomonas aerolata sp. nov., represented by strains NW12T (=DSM 14746T=LMG 21376T), Ant 20 (=ICMP 13599) and M3C203B-B (=SMCC M3C203B-B).

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 WP1T, 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, WP1T 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 C18 : 1 ω7c, along with C19 : 0 cyclo ω8c and C16 : 0. Other fatty acids present in smaller amounts were C17 : 0, C18 : 0, C16 : 1 ω7c, C20 : 1 ω7c and C18 : 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 WP1T 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 WP1T=CIP 107386T =DSM 14790T).

Several strains of moderately halophilic and mesophilic bacteria were isolated at the head of an oil-producing well on an offshore platform in southern Vietnam. Cells were Gram-negative, non-spore-forming, rod-shaped and motile by means of a polar flagellum. Growth occurred at NaCI concentrations between 0 and 20%; the optimum was 5% NaCI. One strain, which was designated VT8T, could degrade n-hexadecane, pristane and some crude oil components. It grew anaerobically in the presence of nitrate on succinate, citrate or acetate, but not on glucose. Several organic acids and amino acids were utilized as sole carbon and energy sources. The major components of its cellular fatty acids were C12:0 3-OH, C16:1 ω9c, C16:0 and C18:1 ω9c. The DNA G+C content was 55·7 mol%. 16S rDNA sequence analysis indicated that strain VT8Twas closely related to Marinobacter sp. strain CAB (99·8% similarity) and Marinobacter hydrocarbonoclasticus (99·4% similarity). Its antibiotic resistance, isoprenoid quinones and fatty acids were similar to those of Marinobacter hydrocarbonoclasticus and Pseudomonas nautica. However, the whole-cell protein pattern of VT8Tdiffered from that of other halophilic marine isolates, including P. nautica. DNA-DNA hybridization indicated that the level of relatedness to Marinobacter hydrocarbonoclasticus was 65% and that to P. nautica was 75%. Further differences were apparent in Fourier-transformed IR spectra of cells and lipopolysaccharide composition. It is proposed that VT8Tshould be the type strain of a new species and should be named Marinobacter aquaeolei. P. nautica may have been misclassified, as suggested previously, and may also belong to the genus Marinobacter.

Based on published results and investigations done for this study, chemotaxonomic characteristics of all validly described species of the genus Sphingomonas, as well as unnamed strains of this genus...

Two airborne bacterial isolates, NS/2 and NS/50^T, were examined in order to determine their taxonomic position. Their almost complete 16S rRNA gene sequences shared 95.9 % similarity. Sequence comparisons demonstrated that their next relatives are species of the genus Hymenobacter (93.6–95.7 % similarity) and the strains ‘Taxeobacter chitinovorans’ Txc1^T, ‘Taxeobacter gelupurpurascens’ Txg1^T and ‘Taxeobacter ocellatus’ Myx 2105^T (90.5–96.4 %). Phylogenetic calculations indicated that these five strains together with the three recognized Hymenobacter species form a separate line of descent within the family ‘Flexibacteraceae’. Isolates NS/2 and NS/50^T, as well as ‘Taxeobacter chitinovorans’ Txc1^T, ‘Taxeobacter gelupurpurascens’ Txg1^T and ‘Taxeobacter ocellatus’ Myx 2105^T, possessed the characteristics of the genus Hymenobacter, the quinone system menaquinone MK-7 and a polyamine pattern with the major polyamine being sym-homospermidine. Each of the five strains had complex, unique polar lipid profiles, with phosphatidylethanolamine and several unknown aminophospho-, amino-, phospho-, glyco- and polar lipids of which several compounds were also found in established Hymenobacter species. All the strains studied possessed fatty acids characteristic of Hymenobacter species, including major acids iso-C_15 : 0, anteiso-C_15 : 0, C_16 : 1 ω5c, summed feature 3 (C_16 : 1 ω7c/iso-C_15 : 0 2-OH) and summed feature 4 (iso-C_17 : 1 I/anteiso-C_17 : 1 B). The five strains could be distinguished from each other and from the three established species of the genus Hymenobacter based on relatively low 16S rRNA gene sequence similarities (<97 %), unique polar lipids and differing fatty acid profiles and physiological characteristics. In conclusion, the description of four novel species of the genus Hymenobacter appears to be justified, for which the names Hymenobacter norwichensis sp. nov. (type strain NS/50^T=LMG 21876^T=DSM 15439^T), Hymenobacter chitinivorans sp. nov. (type strain Txc1^T=LMG 21951^T=DSM 11115^T), Hymenobacter gelipurpurascens sp. nov. (type strain Txg1^T=LMG 21873^T=DSM 11116^T) and Hymenobacter ocellatus sp. nov. (type strain Myx 2105^T=Txo1^T=LMG 21873^T=DSM 11117^T) are proposed. For strain NS/2, a description only is provided without proposal of a name because its status as a novel species was not demonstrated unambiguously.