Intergeneric complementation of Escherichia coli recA mutants was used to identify recombinant plasmids, within a genomic library derived from Zymomonas mobilis, that carry Z. mobilis recA-like gene. Screening of 1100 individual E. coli strains revealed four clones expressing the recA+ character. On restriction analysis, all four recombinant plasmids were found to be related and to exhibit a common 6.7-kb fragment. Consequently, one of the four recombinant plasmids, pZR27, was selected for further characterization. When introduced into E. coli recA mutants, pZR27 restored resistance to methyl methane sulfonate, mitomycin-C, and UV irradiation, as well as recombination proficiency when measured by standard Hfr-mediated conjugation. The cloned recA-like gene also restored the spontaneous and mitomycin-C-induced phage production. The origin of the insert in pZR27 from the chromosome of Z. mobilis was confirmed by Southern transfer and DNA hybridization. However, no homology was found between the recA of E. coli and Z. mobilis chromosomal insert DNA. The Z. mobilis recA-like gene also encoded a major polypeptide of 38-kDa on SDS-PAGE.