Investigation of Appropriate Cultivation Approach for Capsular Polysaccharide Production by Streptococcus pneumoniae Serotype 19F

Abstract

With the aim of determining an appropriate cultivation approach for the capsular polysaccharide production by Streptococcus pneumoniae serotype 19F, the influence of environmental and culture medium conditions on the pneumococcal culture was investigated. Using 5% CO2 atmosphere instead of using an aeration limited environment enhanced the capsule production 3.5 fold. Buffering the cultivation medium prevented the culture pH drop to the acidic condition and increased the capsule production almost 5 fold. Utilizing casamino acid as the nitrogen source of the culture medium instead of soytone provided 1.3 fold increase in the capsule production. Glucose, sorbitol, lactose and sucrose were investigated as carbon sources of the culture medium. Regarding costs of these sugars and their effects on the capsule production, lactose was the best carbon source. Our results demonstrated that buffering the cultivation medium had the most profound effect on the serotype 19F capsule production. The capsule was produced at 1.706 mg/ml in the buffered medium. Applying this culture method allows the cost effective production of the serotype 19F pneumococcal capsule for inclusion in pneumococcal vaccines.