Escherichia coli C29 Alkaline Phosphatase Enzyme Activity and Protein Level in Exponential and Stationary Phases

Abstract

Alkaline phosphatase is a homodimeric periplasmic protein that catalyzes the hydrolysis of phosphate molecules from non-transportable organophosphates. The Escherichia coli ( E. coli ) C29 strain constitutively produces alkaline phosphatase; however, it has been previously reported that alkaline phosphatase enzyme activity ceases during stationary phase. The aim of this study was to confirm these previous results by investigating the trends of alkaline phosphatase specific activity and protein levels throughout exponential and stationary phases. E. coli C29 cells were assayed for alkaline phosphatase activity and protein levels throughout 120 hours of culture. Contrary to the previous observation, the alkaline phosphatase activity in E. coli C29 did not decrease upon entry into stationary phase but, rather, increased following exponential growth. Moreover, the increase in alkaline phosphatase activity in stationary phase did not correspond to an equivalent increase in the amount of alkaline phosphatase protein. Further investigation into this phenomenon would assist in the elucidation of these trends in alkaline phosphatase activity observed over time in E. coli C29.