Structure of the 021 antigen from Serratia marcescens.

Lipopolysaccharide was isolated from both phases of an aqueous-phenol extraction of defatted cell walls from the reference strain for Serratia marcescens serogroup 021. The product from the aqueous phase was of the R type, lacking a polymeric side-chain. The polymeric fraction of the lipopolysaccharide from the phenolic phase (the 021 antigen) had a disaccharide repeating-unit with the following structure: ----4)-alpha-D-Glcp-(1----4)-beta-D-ManpNAc-(1----.