Purification of the O antigen of Bacteroides fragilis ss. fragilis NCTC 9343 from phenol-water extracts by gel filtration and chromatography on deae-cellulose and hydroxylapatite.

O antigen extracted from whole cells of Bacteroides fragilis ss. fragilis NCTC 9343 with 45 per cent aqueous phenol has been purified by gel filtration and chromatography. First, the water phase was treated with RNase and DNase and passed through a column of agarose. The chromatographic procedures included ion exchange on a column of DEAE-cellulose and adsorption to hydroxylapatite. The O antigen was eluted from the DEAE-cellulose with a gradient of NaCl, and from the column of hydroxylapatite with 1 M phosphate buffer, pH 6.8. Inhibition of indirect haemagglutination was used to detect the O antigen in the eluates.