The Effect of Inoculum Size on Proliferation of NCTC Strain 2071, the Chemically Defined Medium Strain of NCTC Clone 929 (Strain L)

Replicate culture and nuclei enumeration procedures were used to study the effect of inoculum sizes of NCTC strain 2071, the chemically defined medium strain of NCTC clone 929 (strain L). The cultures were grown in T-15 flasks containing 3.0 ml. of NCTC 109 medium which contains no added protein. The replicate culture procedure was altered slightly to compensate for the omission of serum; such alterations are described. Initial cell density ranged from 15,500 to 2,001,900 per 3.0 ml. Inoculums between 15,500 and 36,600 were unpredictable with respect to survival and proliferation, but even with an inoculum of 15,500 some cultures proliferated. Inoculums of 36,600 or more per 3.0 ml. showed proliferation of all cultures in each set. Between 36,600 and 1,031,200, the rate of proliferation was never less than 2 at 7 days. The optimum range of inoculum size appeared to be between 160,000 and 410,000. The rate of proliferation of cultures inoculated with optimum densities was highest of all. The maximum cell population attained per culture was not dependent on the initial cell inoculum.