An efficient and convenient method of introducing transposable elements into acetic acid bacteria was developed by the method of conjugal transfer. The ampicillin-resistant strain, Acetobacter sp. HA, was selected to be conjugated with two E. coli strains, WA803 containing pGS9 and AC8001 harboring pJB4JI. The Tn5 containing suicide vector pGS9 or pJB4JI, was transferred from E. coli to Acetobacter sp. HA and kanamycin-ampicillin-resistant transconjugants obtained at high frequencies. The conjugal frequencies of pGS9 and pJB4JI were 6.20$ imes$$l0^{-1} and 2.79$ imes$l0{-1}$</TEX> per recipient, respectively. The transfer method was applied on four different strains of Acetobacter. The conjugal transfer frequencies ranged from 2.00$ imes$$l0^{-2} to 4.45$ imes$l0^{-8}$</TEX> per recipient in the three strains. Some transconjugants tested were found to contain Tn5 DNA in their genomes and this was confirmed by Southem blot analysis. This is the first study which shows that Tn5 mutagenesis can be applied to successfully isolate mutants of Acetobacter genus.