CELLULAR POLYSACCHARIDES OF SERRATIA MARCESCENS

Abstract

Decapsulated cells of Serratia marcescens were fractionated to yield crude cytoplasmic (I) lipopolysaccharide (II) and cell-wall (III) polysaccharides. Further separation of I yielded dialyzable polysaccharides composed of D-glucose and D-mannose and nondialyzable polysaccharides containing various proportions of D-glucose, D-mannose, L-rhamnose, glucuronic acid, and glucosamine. Fractionation of II by precipitation with Cetavlon–boric acid and by highspeed centrifugation yielded polysaccharides containing D-glucose, L-rhamnose, D-mannose, D-glycero-D-manno-heptose, L-glycero-D-mannose-heptose, glucuronic acid, mannuronic acid, and glucosamine. Analytical data on the various fractions indicated that these polysaccharides included an acidic glucomannan, a rhamnoglucan, and a heptoglucan. Polysaccharides of similar composition have been found in S. marcescens capsular and extracellular polysaccharides in an earlier investigation. Removal of the mucopeptide material from the cell-wall III left an insoluble polysaccharide residue composed of glucose and glucosamine units.