Study On The Plasmids Of Acacia Rhizobium

The growth behavior of 20 strains of Acacia Rhizobium in solid and liquid mediums of different concentration of five kinds of antibiotics and the plasmid of Acacia Rhizobium were studied in this paper. On this base, we found plasmid pMC73A can be transfered from Koxytoca NG13 to Acacia Rhizobium (MZ and AJ018) by conjugation. The nodulation ability, ammonia tolerance and nirogenase activity of exconjugants were also studied in this paper.1) The antibiotic resisance of of 20 strains of Acacia Rhizobium has obvious difference. Most srains are sensitive to Km and Sm, YM2 has no tolerance to all antibiotics while 4-2 srain has antibiotic resisance to all antibiotics. Tc was selected for the antibiotic filter sign of MZ and AJ018 Strains.2) Plasmids of Acacia Rhizobium were detected with three different methods. The results showed that alkaline lysis method was suitable for Acacia Rhizobium. The plasmids of Acacia Rhizobium were studied in this paper. The results showed that most strains each has one plasmid while there are no plamids detected in LR005 strain. The plasmid conditions were opitimized and the suitable volume of bacteria is about 20ml.3) Plasmid pMC73A can be transferred from Koxytoca NG13 to Acacia Rhizobium MZ by conjugation, and the transfer frequency are 8.0×10^-8.The plasmid stability showed the plasmid can be maintained in MZ. The elesrophresis examination showed that the strap of pMC73A could be seen in MZ exconjugant but could not been seen in AJ018 exconjugant.4) The resuls of Acacia Rhizobium seedings inoculaed with 34 strains in test tubes showed that nodule could been seen in all the host seedings. MZ1, MZ2, MZ4, M12, AJ7 and AJ9 are those strains which have better nodule ability than wild strains.5) The study of ammonia tolerance and nirogenase activity showed that MZ1, MZ2, MZ4, M12, AJ7 and AJ9 strains had growth behavior in the liquid mediums of different concentration of (NH₄)₂SO₄. All the strains could not keep normal nitrogen...