Polymer production by Lactobacillus delbrueckii ssp. bulgaricus

A polymer‐forming strain of Lactobacillus delbrueckii ssp. bulgaricus was grown under differing conditions. It was found that at higher temperatures and slower growth the production of the polymer per cell was greater. Polymer‐producing ability seems to be unstable with cells losing the phenotype faster at 48 than at 40°C. Specific production of polymer was increased in the presence of hydrolysed casein early in the growth phase when growing in milk, but production of polymer in MRS broth + lactose was reduced compared with milk. Furthermore, addition of hydrolysed casein to MRS did not increase specific production of polymer. Preliminary results suggest that the polymer is a glycoprotein, although the protein may be loosely associated with the carbohydrate.