Estimating bacterial growth parameters by means of detection times

We developed a new numerical method to estimate bacterial growth parameters by means of detection times generated by different initial counts. The obs erved detection times are subjected to a transformation involving the (unkn own) maximum specific growth rate and the (known) ratios between the differ ent inoculum sizes and the constant detectable level of counts. We present an analysis of variance (ANOVA) protocol based on a theoretical result acco rding to which, if the specific rate used for the transformation is correct , the transformed values are scattered around the same mean irrespective of the original inoculum sizes. That mean, termed the physiological state of the inoculum, <(alpha)over cap>, and the maximum specific growth rate, mu, can be estimated by minimizing the variance ratio of the ANOVA procedure. T he lag time of the population can be calculated as lambda = -In <(alpha)ove r cap>/mu; i.e, the lag is inversely proportional to the maximum specific g rowth rate and depends on the initial physiological state of the population . The more accurately the cell number at the detection level is known, the better the estimate for the variance of the lag times of the individual cel ls.