Transfer of broad host-range plasmids to sulphate-reducing bacteria

The broad-host-range, IncQ, plasmid R300B (Sm, Su) has been stably transferred to two strains of sulphate-reducing bacteria (Desulfovibrio sp. 8301 and Desulfovibrio desulfuricans 8312), using the IncP1 transfer system of the helper plasmid pRK2013 and cocultivation of sulphate-reducing bacteria with facultative anaerobes in media provided with sulphate and nitrate ions as electron acceptors. R300B was transferred at a frequency of 10−2 to 1 per acceptor cell. The SmR marker was expressed in both sulphate-reducing bacteria strains while the SuR was expressed only in strain 8301. R300B can also be transferred back to E. coli strains provided with IncP1 plasmids taking advantage of the retrotransfer ability of these plasmids. This occurs at a frequency up to 10−4 by recipient E. coli cell.