Pigment production in chemostat cultures of Streptococcus bovis - II. Effect of carbon dioxide and pH on pigment and glucose end-products

Seven of eight type strains of Streptococcus bovis, including all 6 rumen isolates tested, produced pigment on agar media if the anaerobic atmosphere was supplemented with CO₂. Tween 80 or NaHCO₃ added to the growth medium could not substitute for gaseous CO₂. When one of the best pigment-forming strains, S. bovis 2B, was grown in a glucose-limited chemostat at constant dilution rate (D), decreasing the concentration of the gas overlay resulted in pigment washout and increased lactate and cell mass. Champing pH at a constant D altered the pigment production and glucose end products of the culture.