Sphingomonas pituitosa sp. nov., an exopolysaccharide-producing bacterium that secretes an unusual type of sphingan.

Abstract

Strain EDIVT , an exopolysaccharide-producing bacterium, was subjected to polyphasic characterization. The bacterium produced copious amounts of an extracellular polysaccharide, forming slimy, viscous, intensely yellowpigmented colonies on Czapek-Dox (CZD) agar. The culture fluids of the liquid version of CZD medium were highly viscous after cultivation for 5 d. Cells of strain EDIV T were Gram-negative, catalase-positive, oxidase-negative, nonspore-forming, rod-shaped and motile. Comparisons of 16S rDNA gene sequences demonstrated that EDIV T clusters phylogenetically with the species of the genus Sphingomonas sensu stricto. The GMC content of the DNA (645 mol %), the presence of ubiquinone Q-10, the presence of 2-hydroxymyristic acid (14 :0 2-OH) as the major hydroxylated fatty acid, the absence of 3-hydroxy fatty acids and the detection of sym-homospermidine as the major component in the polyamine pattern, together with the presence of sphingoglycolipid, supported this delineation. 16S rDNA sequence analysis indicated that strain EDIV T is most closely related (994 % similarity) to Sphingomonas trueperi LMG 2142 T . DNA-DNA hybridization showed that the level of relatedness to S. trueperi is only 455 %. Further differences were apparent in the cellular fatty acid profile, the polar lipid pattern, the Fouriertransform infrared spectrum and whole-cell proteins and in a number of biochemical characteristics. On the basis of the estimated phylogenetic position derived from 16S rDNA sequence data, DNA-DNA reassociation and phenotypic differences, strain EDIV T (l CIP 106154 T l DSM 13101 T ) was recognized as a new species of Sphingomonas, for which the name Sphingomonas pituitosa sp. nov. is proposed. A component analysis of the exopolysaccharide (named PS-EDIV) suggested that it represents a novel type of sphingan composed of glucose, rhamnose and an unidentified sugar. Glucuronic acid, which is commonly found in sphingans, was absent. The mean molecular mass of PS-EDIV was approximately 3i10 6 Da.Keywords : Sphingomonas pituitosa sp. nov., polyphasic characterization, exopolysaccharide, sphingan INTRODUCTION Interest in the genus Abbreviations :FT-IR, Fourier-transform infrared ; PHB, poly-β-hydroxybutyrate.The EMBL accession number for the 16S rDNA sequence of Sphingomonas pituitosa strain EDIV T is AJ243751.increasingly intense, as there have been several recent reports on the broad catabolic capabilities of strains of Sphingomonas species. These organisms have great potential for biotechnological applications in the degradation, bioremediation and wastewater treatment of xenobiotic pollutants (e.g. Fredrickson et al., 1991Fredrickson et al., , 1995 Harms et al., 1995 ; Karlson et al., 1995 ;Mueller et al., 1990 ; Nohynek et al., 1996a, b E. B. M. Denner and others et al., 1992 ; Zipper et al., 1996), as bacterial antagonists of phytopathogenic fungi (Berg & Balin, 1994) and for the production of industrially useful exopolysaccharides (Moorehouse, 1987 ;Chandrasekaran & Radha, 1995). Certain structura...

Structural characterization of the exopolysaccharide PS-EDIV from Sphingomonas pituitosa strain DSM 13101

“…The molecular mass of the sphingan PS-EDIV found by Denner et al was 3 × 10 6 Da (Denner et al 2001). In contrast, the molecular mass determined in this study was only 1.2 × 10 6 Da, but these values are yet of the same magnitude.…”

“…The exopolysaccharide (EPS) PS-EDIV, which is produced by this strain, reveals a high viscosity even at low concentrations. Moreover, this high viscosity is stable at high ionic concentrations, at various pH-values, and over a wide range of temperature as described by Denner et al (2001). With its distinct thickening properties it could thus be a potential alternative to xanthan gum.…”

“…The bacterial strain used in this work was described by Denner et al and is deposited at the DSMZ as DSM 13101 (Denner et al 2001 …”

“…Sphingomonas pituitosa DSM 13101 was isolated and characterized by Denner et al (2001). The exopolysaccharide (EPS) PS-EDIV, which is produced by this strain, reveals a high viscosity even at low concentrations.…”

Pseudochrobactrum glaciei sp. nov., isolated from sea ice collected from Peter the Great Bay of the Sea of Japan

“…For the polar lipid and fatty acid analyses, strain KMM 3858 T was cultivated on TSA at 28 u C for 3 days, and the lipids were extracted using the chloroform/ methanol extraction method of Bligh & Dyer (1959). The polar lipids were analysed as described by Denner et al (2001). Fatty acid methyl esters were obtained using alkaline methanolysis [15 % (w/v) NaOH/methanol].…”