An Automated System for Rapid Non-Destructive Enumeration of Growing Microbes (original) (raw)
Figure 7
Demonstrating the method is non-destructive.
To show that the light and heat stress occurring during processing on the Growth Direct System do not harm cells, we tested the ability of standard test strains to withstand stresses more extreme than those that would normally be experienced on the Growth Direct System. To test the effect of light stress, microbes were exposed to 10 times the level of blue light that they would actually experience on the system (top six lines). To test the effect of heat stress, P. fluorescens was subjected to an imaging cycle at an elevated temperature (second from the bottom) and to an accelerated imaging regime which caused heat and imaging cycles to occur at twice the normal frequency (bottom line). To test the equivalence in microbial recovery for samples with and without stress, we used the TOST method. The figure plots the percent difference of the mean titer of the stressed samples vs. the untreated controls (•) and indicates the 95% confidence intervals. The number of replicates for each experiment and the total number of colonies analyzed are indicated above each line.