Growth studies on the lactic streptococci: II. The effect of agitation on the growth characteristics ofStreptococcus lactisML₈in batch culture

Summary Investigations on the growth characteristics of Streptococcus lactis ML 8 in skim-milk medium have indicated that agitation of the medium may decrease the growth rate of the organism by decreasing the availability of CO 2 (CO 2 effect) and of soluble nitrogen (soluble nitrogen effect). The former effect was observed only when the CO 2 concentration was depleted by heat sterilization; the latter occurred when a certain threshold level of agitation was exceeded. Results suggested that the soluble nitrogen affect was caused by an alteration in the rate of diffusion of substances formed in the immediate vicinity of the bacterial cell by the proteolytic enzyme system.