ISOLATION AND CHARACTERIZATION OF ENTEROBACTER-CLOACAE MUTANTS WHICH ARE DEFECTIVE IN CHEMOTAXIS TOWARD INORGANIC-PHOSPHATE

Enterobacter cloacae IFO3320 is attracted to P-i when cells are starve d for P-i, Two TN1737KH-induced mutants, which were constitutive for a lkaline phosphatase, failed to exhibit P-i taxis even under conditions of P-i limitation. Both of the mutant strains exhibited normal chemot actic responses to peptone, suggesting that they are specifically defe ctive in P-i taxis, Cloning and sequence analysis showed that the TN17 37KH insertions were located in either the pstA or pstB genes which en code the channel-forming proteins of the P-i-specific transport (Pst) system in E. cloacae. These results suggest that the E. cloacae Pst sy stem is required for P-i chemoreception.