Quantitative Characteristics of Growth

In batch culture the kinetics of growth is described by the Monod equation  

This formula applies only when the concentration of lactate used as a substrate is below 1.2%. When the lactate concentration is higher, the growth rate is limited by the end products formed during fermentation, first 

The dependence of the specific growdi rate on initial substrate concentrations is shown in Table 4.7. Increasing the glucose concentration from 1.2 to 2.2% had little effect, while increasing ihe lactate concentration from 1.3 to 2.5% depressed the specific growth rate of P. shermanii almost twofold (Gaitan and Vorobjeva, 1981). 

Growth yield coefficients, 7g, were measured by Babuchowski et al. (1987) in three species of propionibacteria P, jensenii, P. acidipropionici and P. thoenii, growing in complex medium with peptone and yeast extract. 

Growing these strains at the maximal glucose concentration tested (0.5%) resulted in the lowest activities of exogenous lipases, hyalouronidases and acid phosphatases in the medium (for more details about extracellular enzymes, see below). This shows that the synthesis of enzymes involved in the utilization of ammo acids can be repressed by glucose (Greenman et al., 1981). 

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