• Korean Journal of Microbiology
• /
• v.27 no.2
• /
• pp.92-97
• /
• 1989

the vector, pGUR19, for Rhizobium gene manipulation, was constructed by combining the replication and mobilization function of indigenous multicopy plasmid from Acacia(Robinia pseudoacacia L.) Rhizobia sp86 with E. coli cloning vehicle, pBR322. The vector could be efficiently mobilized by RP4 tra function incorporated into chromosome of E. coli named SM10 and efficiently transferred to various gram negative hosts including Rhizobium and Afrobacterium by transformation. Mobilization frequency of the constructed vector was ranged from $1.2\times 10^{-2}$ (E.coli HB 101) to $4.6\times 10^{-4}$ (A. tumefaciens 15955) and transformation frequency was ranged from $5.4\times 10^{-7}$(E. coli HB101) to $1.2\times 10^{-10}$ (A. tumefaciens 15955). The vector, pGUR19, was stably replicated and maintained in a variety of Rhizobium and Agrobacterium.

• Applied Biological Chemistry
• /
• v.41 no.1
• /
• pp.53-59
• /
• 1998

The Rhizobium and Azospirillum spp. were isolated from the root nodules of several leguminous plants and rhizosphere of various paddy rice varieties. The growth of the nitrogen-fixing strains isolated was largely inhibited in yeast extract-mannitol medium (AMA) containing 0.6 M NaCl. In response to osmotic stress, the nitrogen-fixing strains accumulate intracellular free glutamate. The growth and nitrogenase activity of Rhizobium and Azospirillum were increased by addition of osmoprotectants such as proline, glycine betaine, and glutamate during salt stress. Glycine betaine was the most effective among exogenous osmoprotectants tested. In the absence of sodium chloride, nitrogenase activity seem to be slightly decreased by the presence of the proline or glycine betaine. These results revealed that nitrogenase activity was repressed by fixed nitrogens such as proline or glycine betaine.