Table 1. Survival of the Na⁺/H⁺ exchanger-deficient E. coli strain KNabc overexpressing K. pneumoniae Na⁺/H⁺ exchangers.

Exchanger	LBK	LBK pH 7 0.6 M NaCl	LBK pH 7 0.1 M LiCl	LBK pH 8.3 0.6 M NaCl	LBK pH 8.3 0.1 M LiCl
KpNhaB	++	+	++	–	–
KpNhaA1	+++	+++	+++	–	++
KpNhaA2	++	+	++	–	–
HpNhaA	+++	+++	+++	–	+++
Vector	+++	–	–	–	–

Survival was assessed under different salt concentration and pH values. Experiments were repeated at least three times with virtually identical results. NhaA from H. pylori (HpNhaA) was used as a positive control, while empty pTrcHis2TOPO vector was used as a negative control. +++ = maximum number of colonies, ++ = moderate number of colonies, + = small number of colonies,– = no growth detected. LBK = LB Broth containing K⁺ instead of Na⁺.