Objectives: To determine whether such PBP5 expression is affected by pH in this microorganism.
Methods: E.faecalis was inoculated in phosphate buffer with pH ranging from 4 to 12 and incubated at 37 Celsius for 8 weeks. The cells were harvested at day1, day3, day5 and every week. After RNA preparation, RT-PCR of the PBP5 was performed and the fluorescence intensity of the amplicons was densitometrically measured and statistically analyzed.
Results: Overall, the PBP5 mRNA expression was detectable until 8 weeks, which was derived from the pH 5-12 buffers; however, it decreased overtime. The level of the mRNA was highest in the cells from the buffers pH 8 and 9. Results from E.faecalis culture on BHI agar revealed positive colonies from the pH 7-9 buffers. No colony was detectable from any buffers by the end of the first week.
Conclusions: Under the limitation of this study, our data indicate the cells may be viable but uncultivable after day7 in the phosphate buffer. Also, pH influences the PBP5 expression in E.faecalis. However, further investigation is required to evaluate the pattern of such expression in relation to the longevity of the cell viability.