Method for Studying Acid Production and Growth in Lactic Cultures

Abstract

During the logarithmic growth phase of cultures of the lactic group of the genus Streptococcus, the relationship between the number of bacterial cells and the acid produced can be described by B = Bo + k/m [image] (where B is the number of bacterial cells at some time during a fermentation, [image] is the amount of acid produced during the same period of time, Bo is the number of bacterial cells at time zero, k is the apparent first order rate constant for growth of the bacterial culture and m is the rate of acid production per cell). By sampling at time intervals during a fermentation and measuring the number of cells and the amount of acid present, data is collected which may be subjected to regression analysis to determine the constants k and m. This method will permit the simultaneous study of the effect of various factors on the growth rate of the culture and on the rate of add production per cell. Data taken during a 4 hr. incubation period at 30C using a culture of S. lactis are presented.