SummaryAs a rate equation of microbial cell growth, the Monod equation is widely used. However, this equation cannot fully correspond to real courses of microbial cell growth in many batch cultivations. Especially, predicted values based on this equation do not agree with observed values in many continuous cultivations. I n this paper, which introduces new concepts of critical concentration and coefficient of consumption activity, the growth rate equation which corresponds to the whole period including lag period is newly derived and characteristics of

SummaryKinetic studies on fermentation processes were made and a general equation of production rate was newly presented applying the kinetic theory on microbial cell growth which was reported previously by the authors.1.2 Equations for product concentration in fermentation time courses were derived by developing mathematically the general equation of production rate, and characteristic properties of fermentation processes were clarified. Some examples of fermentations were analyzed kinetically using the new kinetic theory. The calculated values of product and cell concentrations were in good agreement with the observed values.

The in-vitro activities of cefmetazole, flomoxef, imipenem, vancomycin and enramycin alone and in combination with cefotiam against eighteen clinically isolated methicillin-resistant Staphylococcus aureus was investigated. Cefotiam, cefmetazole, flomoxef and imipenem inhibited the growth of clinical isolates at concentrations ranging from 100 to 1600, 6.25 to 400, 6.25 to 400 and 0.78 to 200 mg/L, respectively. Synergic effects were observed with combinations of cefotiam and cefmetazole, flomoxef or imipenem against more than 70% of the strains. The fractional inhibitory concentration (FIC) index values were less than 0.1. Vancomycin and enramycin alone inhibited the growth of all strains at concentrations ranging from 0.39 to 1.56 mg/L and 0.2 to 0.78 mg/L, respectively. Moreover, vancomycin and enramycin in combination with cefotiam showed synergy against strains in which no synergic effects were observed when cefotiam was combined with other beta-lactam agents. About 50% of the strains tested were inhibited synergically by cefmetazole, flomoxef or imipenem, at clinically relevant concentrations in combination with 0.78 mg/L of cefotiam. The effects of vancomycin or enramycin in combination with cefotiam on the growth of a homogeneous resistant clone, which was derived from one of the clinical isolates, TS-65, was also studied. Regrowth in the presence of vancomycin or enramycin alone was suppressed when cefotiam was added.

SummaryKinetic studies were made on continuous cultivation applying the theory of microbial cell growth that was derived previously by the authors introducing the concepts of critical concentration and coefficient of consumption activity. General equations for microbial cell concentration for continuous cultivation in continuous-stirred tank and tubular type reactors were derived theoretically. Productivity of cell mass in continuous cultivation was analyzed kinetically and the behavior of mutant populations in continuous cultivation is briefly discussed.