An alkaline phosphatase (phoA) gene from Zymomonas mobilis was isolated in Escherichia coli CC118 by use of the plasmid Bluescript KS+ . The origin of the 6.4-kb DNA fragment in pZAP1 from the chromosome of Z. mobilis was confirmed by Southern blotting and hybridization studies. The Z. mobilis phoA gene was localized at one end of the chromosomal insert on plasmid pZAP1. The Z. mobilis phoA gene was expressed from its own promoter in E. coli, and the enzyme was localized to the periplasmic space. Z. mobilis alkaline phosphatase activity in E. coli was repressed in high-phosphate media and derepressed under a phosphate-limited growth condition. These results suggest that Z. mobilis alkaline phosphatase is subjected to normal regulation in E. coli.