Abstract: Experiments were undertaken to determine the growth of E. sakazakii under different temperatures by microplate luminometer. 16 Strains of 17 E. sakazakii strains (including ATCC 29544) used in this study were isolated from dried infant milk formula powder on China retail market. The results showed that the E. sakazakii counts determined by microplate luminometer are perfectly correlated with those determined by conventional plate counting method (r=0.92). E. sakazakii in brain heart infusion broth can be quickly monitored with much shorter time (no more than 10 h) than that of conventional plating method (at least 24 h). Although at the end of incubation the amounts of E. sakazakii strains are close under 36 ℃, but the growth curves are different. And the further research results of 17 E. sakazakii strains being incubated at 42 ℃ indicated that the microplate luminometer method provides a convenient, rapid and real-time way to monitor the growth of E. sakazakii. The results suggested that this microorganism can be divided into different phenotypes according to their different growth characters, which are consistent with phenotypes divided into according to their different biochemistry reactions.

Key words: Enterobacter sakazakii, miroplate luminometer, plate counting method