Media and fermentation methods for producing polysaccharides in bacterial cell culture

A method of cultivating a polysaccharide-producing bacteria selected from Streptococcus pneumoniae and Streptococcus agalactiae, comprising:

• (a) adding a defined medium to a bioreactor, wherein said defined medium comprises
• (i) a total amino acid concentration of at least 60 mM;
• (ii) a total glycine concentration of between 1.5 mM and 60.0 mM;
• (iii) a total potassium chloride concentration of between 0.31 g/L and 24.31 g/L;
• and
• (iv) a carbon source;
• (b) seeding the defined medium with the polysaccharide-producing bacteria;
• and
• (c) cultivating the bacteria by fermentation, wherein a nutrient is added during the cultivating step.