THE IMPACT OF PULSED LIGHT ON THE INACTIVATION OF ENTEROCOCCUS FAECALIS V583 IN TWO DIFFERENT GROWTH PHASES

Abstract

The aim of the study was to evaluate the impact of pulsed light on the inactivation of Enterococcus faecalis V583 in the exponential and stationary phases. The suspension of Enterococcus faecalis in these two phases was treated using pulsed light with the intensity of 0, 0.00002, 0.06, 0.2, 0.3, 0.5 and 0.6 J/cm². The suspension was evaluated on the number of colonies, the impact on cell membranes and the recovery of microorganism. The results showed that Enterococcus faecalis in the exponential phase was more sensitive with pulsed light than the rest phase was. The inhibition of Enterococcus faecalis in the exponential and stationary phases needed the pulsed light intensity of 0.5 and 0.6 J/cm² respectively. The results also indicated that the cell membranes of microorganism in the stationary phase was impacted less than the one in the exponential phase. Therefore, the recovery of microorganism in the exponential phase was slowly than the one in the stationary phase.