An O polysaccharide was prepared by mild acid hydrolysis of a lipopolysaccharide of Erwinia carotovora ssp. atroseptica GSPB 9205 and was found to contain a new higher branched monosaccharide, viz., 3,6,8 trideoxy 4 C (R 1 hydroxyethyl) D gulo octose, which we called erwiniose. The structure of the pentasaccharide repeating unit of the O polysaccharide was established by monosaccharide analysis, including the determination of absolute configura tions, methylation analysis, O deacetylation, Smith degradation, and one and two dimen sional NMR spectroscopy. The configuration of erwiniose was determined based on the cou pling constants of vicinal protons combined with the nuclear Overhauser effect data and the results of periodate oxidation of the polysaccharide followed by reduction of the resultant 4 keto sugar (the C(1)-C(4)-C(1´)-C(2´) fragment) to give 3,6 dideoxy D ribo hexose (paratose) and oxidation of 3 hydroxybutyraldehyde (the C(5)-C(8) fragment) to give R 3 hydroxybutyric acid.Lipopolysaccharide (LPS) forms the outer layer of the outer membrane of the Gram negative bacteria cell walls. The fine structure of the O polysaccharide chain of the LPS is responsible for intraspecies diversity of strains and specificity of interactions of bacterial cells with other bio logical systems. Classification schemes of many Gram negative bacteria necessary for epidemiologic monitoring are based on O polysaccharide structures.Lipopolysaccharides of phytopathogenic bacteria are involved in plant pathogenesis, for example, in soft rot caused by Erwinia carotovora strains. The structure of LPS of bacteria belonging to the Erwinia genus was poorly studied. 1-5 The structures of O polysaccharides were es tablished only for two strains, viz., E. carotovora ssp. atroseptica GSPB 436 1 and Erwinia amylovara T. 4 The classification scheme of bacteria Erwinia is lacking. With the aim of classifying strains of phytopathogenic bacteria, we perform a series of structural studies of their O poly saccharides. In the present study, we established the structure of the O polysaccharide of E. carotovora ssp. atroseptica GSPB 9205. We found and identified a new higher branched monosaccharide in this O polysaccharide and called it erwiniose. Results and DiscussionMild acid degradation of LPS, which was isolated from E. carotovora ssp. atroseptica GSPB 9205 cells by aque ous phenol extraction, afforded an O polysaccharide (1). Monosaccharide analysis by GLC of alditol acetates ob tained upon total acid hydrolysis of polysaccharide 1 re vealed the presence of galactose, mannose, and rhamnose in a ratio of 2 : 1 : 1. The GLC analysis of acetylated glycosides with an optically active alcohol, viz., S octan 2 ol, revealed D configuration for galactose and mannose and L configuration for rhamnose. Methylation analysis of the polysaccharide revealed 3 substituted galactose resi dues, a 4 substituted rhamnose residue, and a 2,3 disub stituted mannose residue. The presence of the latter monosaccharide is indicative of a branched structure of the polys...
A survey in 1987 and 1988 revealed that basal glume rot, caused by Pseudomonas syringae pv. atrofaciens, occurred nearly everywhere in FRG. The symptoms of the disease usually consisted of water‐soaked dark green to brown lesions on unripe wheat heads, mainly at the basal end of the glumes, which later became dark brown. Forty‐six isolates of P.s. atrofaciens were obtained from glumes, seeds and leaves of wheat and barley. For a fast identification of the isolated bacteria, a bio‐assay was developed. Four to five‐day‐old wheat seedlings, grown on wet filter paper in Petri dishes, were pricked at two‐three sites with a dissecting needle contaminated with bacteria. After 2–3 days, pathogenic isolates induced brown to black spots. The bacterial isolates from wheat inhibited the growth of several fungi grown on potato dextrose agar. In contrast, an authentic isolate of P.s. syringae obtained from wheat showed no inhibitory effect. During screening for resistance, several cultivars of spring and winter wheat were tested in the greenhouse and/or field tests. The results revealed marked differences in the susceptibility of different cultivars.
A semi-selective medium for isolation of Xanthomonas axonopodis pv. vignicola from cowpea (Vigna unguiculata) plant and soil samples was developed. Twelve carbon and five nitrogen sources were tested with four strains of X. axonopodis pv. vignicola, and 25 antibiotics were screened against saprophytes. D D -cellobiose (10 g) was selected as the optimal carbon source. Among the antibiotics, cefazoline inhibited growth of most of the saprophytes with little effect on strains of the pathogen. D D ,L L -methionine enhanced growth of X. axonopodis pv. vignicola. Boric acid along with ammonium chloride suppressed growth of Pseudomonas fluorescens. The semi-selective medium designated as cefazoline-cellobiose-methionine (CCM) medium contained K 2 HPO 4 1.34 g, KH 2 PO 4 0.4 g, MgSO 4 0.3 g, H 3 BO 3 0.2 g, NH 4 Cl 1.0 g, D D -cellobiose 10 g, cycloheximide 0.2 g, D D ,L L -methionine 1.0 g, cefazoline 10 mg and agar 14 g per l of water (pH 7.2). Colonies of X. axonopodis pv. vignicola on CCM medium were whitish, round, raised and 0.2-1.8 mm in diameter 96 h after incubation. CCM medium generally inhibited growth of Pantoea agglomerans, Bacillus subtilis and saprophytes isolated from cowpea leaves. Colonies of Pseudomonas fluorescens and a saprophytic bacterium, which were not completely suppressed by CCM, could be differentiated from X. axonopodis pv. vignicola by their smaller size and different color. The CCM medium proved useful for isolation of X. axonopodis pv. vignicola from cowpea plant and soil samples. This is the first report of a semi-selective medium developed for detection of X. axonopodis pv. vignicola.
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