MXYOBACTERIAL POLYSACCHARIDES

Abstract

Specific micromethods have been applied to the analyses of polysaccharides produced by various strains of Myxobacteria. The polysaccharides studjed were - associated with bacillary forms in liquid and on solid culture; isolated from fruiting bodies; and phenol-extractable lipopolysaccharides. A study of four Myxococcus strains indicated that polysaccharides secreted by bacillary forms grown on solid or liquid media closely resembled the polymers isolated from the corresponding fruiting bodies. All three polysaccharide preparations from each strain were essentially similar in gross composition, but differences between the strains were observed. D-glucose and D-mannose were the major monosaccharides present in all the polysaccharide preparations. D-galactose was present in the polymers from three strains and N-acety1-D-glucosamine in one only. The non-identity of polymers from different strains was confirmed by periodate-oxidation, which revealed differential destruction of monosaccharides. It also indicated that the polysaccharides from any one strain produced on solid or in liquid culture and in fruiting bodies were very similar, if not identical. Some of the monomers present in exopolysaccharides were also found in the lipopolysaccharides, but other monosaccharides were also detected. Periodate oxidation destroyed all the neutral sugars present in the lipopolysaccharides. The microcysts isolated from fruiting bodies differed from bacilli in their polysaccharide composition; LPS was apparently absent. In one strain, the major neutral monosaccharides detected in hydrolysates of whole cysts were glucose and an unidentified component. Rhamnose, mannose and galactose, the major products identified in LPS hydrolysates, were all absent. This provides further evidence for the absence of LPS from cysts. These studies have been extended to other strains of fruiting Myxobacteria. They indicate that the exopolysaccharides are composed of a very limited range of sugars, but that differences in composition or structure do exist between strains although probably not between fruiting body and bacillary products. A comparision has been made between Myxozcoccus and one Cystobacter strain in all available respects, using bacilli and microcysts. These and other results will be discussed.