REPLICON CONTAINING HYDROGEN-UPTAKE GENE; IDENTIFICATION OF BACTERIAL COLONIES WITH HYDROGEN-UPTAKE ACTIVITY; AND ENHANCEMENT OF NITROGEN FIXATION IN LEGUMINOUS PLANTS

摘要

Two essentially pure replicons, pHU1 and pHU2 (obtainable from ATCC 39195 and 39196), are produced by combining a cloning vector and insert DNA isolated from a biologically pure culture of the bacterium Rhizobium japonicum strain 122 DES. When either pHU1 or pHU2 is transferred into a point mutant strain of Rhizobium japonicum, PJ17nal (ATCC 39194), that lacks the capacity for synthesis of a hydrogen gas oxidizing system (Hup), the recipient strain PJ17nal, acquires the capacity for hydrogen gas oxidation. Similarly, transfer of the constructed replicons, pHU1 and pHU2, into another R. japonicum point mutant, PJ18nal (ATCC 39193), converts this strain into an H2-oxidizing strain. Insert DNA in these replicons, therefore, contains genetic information essential for conversion of Hup- strains of Rhizobium to Hup+. Pure strains of nitrogen-fixing microorganisms containing the insert DNA, when administered to legumes, cause H2 produced during nitrogen fixation to be oxidized and thereby increase the amount of energy available for nitrogen fixation.