Zymomonas mobilis phoA gene encoding alkaline phosphatase was expressed in Escherichia coli CC118 carrying the recombinant plasmid pZAP1. The pH optimum for this enzyme was 9.0 and showed a peak activity at 42-degrees-C. This enzyme required Zn2+ for its catalytic activity; however, Mg2+ or Ca2+ significantly affected the activity. This enzyme was found to be ethanolabile, and ethanol inhibition was reversed by addition of Zn2+. Kinetics of Z. mobilis alkaline phosphatase production in E. coli CC118 (pZAP1) showed that the enzyme activity was growth associated and localized in the cellular fraction, and the maximum activity was found in the stationary phase.