Factors affecting polysaccharide storage in group A Streptococcus pyogenes in non-proliferating cell suspensions

Optimal conditions for intracellular polysaccharide (IPS) storage by non-proliferating suspensions of group A Streptococcus pyogenes are described. Concentrations of yeast extract and acid-hydrolysed casein which did not support measureable growth prevented bacterial death during storage. For optimal storage, high concentrations of maltose were required to antagonize the inhibitory effect of medium glucose released by intracellular amylomaltase activity. Stabilization of cell washing solutions with 0.5 M sucrose and the minimal storage medium with 8.0% w/v polyethylene glycol MW 6,000 was required for optimal culture viability and IPS storage. The stabilization effect prevented loss of small purine or pyrimidine-containing compounds required for IPS storage as indicated by culture water-shock treatment.