Chemical characterization of extracellular polysaccharides produced by Actinomyces viscosus T14V and T14Av.

The human isolates Actinomyces viscosus T14V and T14Av produced extracellular polysaccharides in the absence of sucrose. In contrast to strain T14V, strain T14Av produced abundant viscous slime polysaccharide in the culture supernatant fluids when grown in a chemically defined medium containing glucose. After resolution of the T14Av polysaccharides into seven fractions, it was demonstrated that two of these exhibited viscous properties and lacked methylpentose and muramic acid. The major slime polysaccharide purified by gel filtration and ion-exchange column chromatography contained 39% (moles percent carbohydrate) galactose, 37% N-acetylglucosamine, 19% glucose, and 5% mannose. Only trace amounts of protein and phosphorus were detected in this preparation. On the other hand, strain T14V produced negligible slime polysaccharide under the same culture conditions. The major extracellular polysaccharide fraction from this strain contained methylpentoses, hexoses, hexosamines, muramic acid, protein, and phosphorus, suggesting that this fraction might be derived from the cell wall.

Immunological properties of Actinomyces viscosus: comparison of blastogenic and adjuvant activities.

A water-soluble extract of Actinomyces viscosus was tested for its capacity to induce deoxyribonucleic acid synthesis in spleen cells from normal mice and to augment the in vitro antibody-forming cell (AFC) response to the T-cell-dependent antigen, sheep erythrocytes (SRBC) by T-cell-deficient adherent spleen cell monolayers from the same mice. Our results indicated that the water-soluble extract induced an in vitro blastogenic response, as assessed by tritiated thymidine incorporation into mouse spleen cells. The water-soluble extract also augmented the antibody response to SRBC. However, after fractionation of the water-soluble extract on Biogel P-300, not all of the fractions induced a blastogenic response and augmented an AFC response to SRBC. This difference in the ability of A. viscosus fractions to induce in vitro responses suggests that the water-soluble extract has multiple immunological properties. Chemical analysis of the water-soluble extract indicated an enrichment for amino acids and amino sugar common to peptidoglycan.