SYNTHETIC PLASMID AND BACTERIA CONTAINING IT

摘要

Bacteria of the genus Rhizobium nodulate legumes and are responsible for nitrogen fixation. The energetics of this process are improved if hydrogen uptake ability (Hup) is imparted to the bacteria to "recycle" some of the hydrogen lost during the nitrogen fixation. Such Hup is observed in a naturally occurring strain of Rhizobium leguminosarum but it was not known how to transfer it to other strains. The present invention provides recombinant plasmids pIJ1008 and pIJ1007 which enable it to be transferred. These plasmids are formed from a transmissible plasmid, synthesised to include a drug-resistance marker, and a plasmid of the naturally occurring strain. Cultures containing the plasmids have been deposited in a culture collection and can he used, after appropriate further crosses as described, to impart Hup to other strains of Rhizobium. In addition, cultures containing the starting transmissible plasmids (pVW5JI and pVW3JI) have been deposited and can be used to prepare strains of Rhizobium containing the same or similar recombinant plasmids. Plant growth analysis in laboratory tests demonstrate that rhizobial strains containing these recombinant nodulation plasmids which confer Hup+ ability are superior to the corresponding Rhizobium field isolates in terms of overall plant growth dependent on symbiotic nitrogen fixation.