A metagenomic library containing 8,000 clones was constructed by using genomic DNA obtained from Chaerhan Salt Lake in northwest China. Three Na+/H+ antiporters, C4-NhaG, C47-NhaG and C49-NhaG that grouped to the NhaG family, were screened and cloned from this metagenome by complementing Escherichia coli strain KNabc (Delta nhaA Delta nhaB Delta chaA) in medium containing 0.2 M NaCl. The three putative Na+/H+ antiporters were membrane proteins with 10, 11 and 11 transmembrane segments, respectively. They enabled E. coli KNabc to grow in medium containing 0.2-0.6 M Na+ or 7-14 mM Li+. Everted membrane vesicles prepared from E. coli KNabc cells carrying C49-NhaG exhibited Na+/H+ and Li+/H+ antiport activities.