Carbon Dioxide Effects on the Growth and Metabolites of Morphological Variants of Streptococcus thermophilus

Abstract

The effects were studied of agitation and addition of C02 and NaHCO3 on growth of two morphological variants of Streptococcus thermophilus CNRZ 368 that differed in their cell morphology and chain length. The growth yield of the diffuse variant (D12) was decreased by agitation of the culture and increased by the addition of C02, Tween 80, and NaHCO3. The growth of the opaque variant (D31) was unaffected either by the agitation or by addition of C02 but was stimulated by addition of NaHCO3. The culture inhibition of D12, when it is agitated, was not reversed by addition of catalase. The results suggest that agitation may exert its influence on growth of D12 through a C02 deficiency. The NaHCO3 did not affect activity of glycolytic enzymes but increased production of lactic, acetic, and formic acids. © 1993, American Dairy Science Association. All rights reserved.