Abstract
In this study a repeated batch production of lactic acid was investigated for the purpose of reducing amount of yeast extract dosage. First batch operation was performed with nutrient rich media(glucose 100-150 g/${\ell}$, and high yeast extract contents; 15 g/${\ell}$), and subsequential batch operations were performed with nutrient poor media(glucose 100-150 g/${\ell}$, and reduced yeast extract contents; 4-5 g/${\ell}$). Volumetric productivities(6.03-6.20 g/${\ell}{\cdot}h$) and substrate conversion rate(94-98%) of eve η subsequential batch operation were maintained with the same level of first batch operation(6.19 g/${\ell}{\cdot}h$, and 99%, respectively), when concentrations of glucose and yeast extract were 100, and 4 g/${\ell}$ respectively.
