Acetobacter methanolicus
MB 58/4 (IMET 10945) synthesises a capsular polysaccharide (CPS) and an O-side chain of a lipopolysaccharide (LPS) built up of the same Gal&Galp repeating unit'. As a part of studies of the cell envelopes and carbohydrates of this species, we now describe the structure of an extracellular polysaccharide (EPS) produced by this strain.
The polymeric fraction, isolated from the culture supernatant solution by dialysis and ion-exchange chromatography, contained rhamnose, glucose, and galactose in the ratios 1.0:1.2:3.8, determined after hydrolysis by g.1.c. of the derived alditol acetates. Incubation of this fraction with bacteriophage Acml (ref.
- gave a polymer and several oligosaccharides that were isolated by gel-permeation chromatography on BioGel P-4 (Fig. 1). Each oligosaccharide contained galactose only. These oligosaccharides and those formed by Acml-mediated depolymerisation of CPS and LPS' were identified by p.c., gel-permeation chromatography, and sugar analysis. Part of the CPS (galactan) was liberated into the culture medium during fermentation.
Further analysis was conducted on the exopolysaccharide (EPS) eluted in the void volume of the column of BioGel P-4. For the large-scale preparation of EPS, a culture supernatant solution of an Acml lysogenic strain of A. methanolicus MB 58/4 (IMET 10945) was used, because this prophage-harbouring strain is strongly reduced' in biosynthesis of the galactan CPS.
Hydrolysis of the purified EPS with 2111 hydrochloric acid gave glucose and rhamnose in the ratio 1: 1, identified by g.1.c. of the derived alditol acetates and with a sugar analyser. Incubation of the hydrolysate with D-glucose oxidase removed the glucose and indicated it to be D.