Bacterial and Bacteroid Properties of Mutants of Rhizobium Trifolii Strain T1 Uncoupled in Oxidative Phosphorylation

Abstract

Using the neomycin-resistance selection technique, mutants uncoupled in oxidative phosphorylation were isolated in R. tri/olii strain Tl. These mutants had no detectable ATP-synthesizing activity and between 8 and 20% of the ATP-degrading activity of their parent strain in the bacterial form. The mutants formed nitrogen-fixing nodules on red, white, and subterranean clovers, and bacteroids isolated from white clover nodules had a high level of ATPase activity of about 70% of that found in bacteroids of their parental strain. The possibility that a new ATPase complex is synthesized when the bacteria differentiate to form bacteroids within the nodule is discussed.

ESTIMATION for THE FUNCTIONAL ACTIVITY of LIPO-OLIGOSACCHARIDE and N-ACETYL-D- GLUCOSAMINE on NODULATION of Medicago and Trifolium

“…of Nottingham, Nottingham, UK.) were maintained on Yeast Extract Mannitol (YEM) (Vincent,1970)and Trifolii Mannitol Yeast (TMY), (Skotnicki and Rolfe, 1979)agar medium respectively. Bacterial suspension were prepared by inoculating liquid YEM or TMY medium with the rhizobial colony from an agar plate .…”

The nifA gene product from Rhizobium leguminosarum biovar trifolii lacks the N‐terminal domain found in other NifA proteins

“…trifotii by a triparental mating between strain ANU843. a derivative of RR1 containing pRt2014 and a derivative of HB101 containing pRK2013, followed by selection on TM plates (Skotnicki and Rolfe, 1979) containing neomycin (150MLg ml ') and tetracycline (5|i.g ml '). The plasmid pPHUI, which is incompatible with pLAFR3, was mobilized into this resultant R.t. bv.…”

The genetic analysis of Rhizobium in relation to symbiotic nitrogen fixation

“…Surprisingly, all five unc mutants were Fix and the bacteroids of two of these were found to have about 70 per cent of the ATPase activity of the wild-type parent strain. This ATPase activity was apparently not correlated with reversion, because no succinate-utilizing bacteria were isolated from bacteroid preparations (Skotnicki and Rolfe, 1979). It appears, therefore, that bacteroids acquire a new ATPase activity synthesized perhaps as a result of bacteroid differentiation (see Skotnicki and Rolfe, 1979).…”

“…This ATPase activity was apparently not correlated with reversion, because no succinate-utilizing bacteria were isolated from bacteroid preparations (Skotnicki and Rolfe, 1979). It appears, therefore, that bacteroids acquire a new ATPase activity synthesized perhaps as a result of bacteroid differentiation (see Skotnicki and Rolfe, 1979). While it is logical to pursue studies of drug-resistant rhizobia, it should be remembered that our understanding of the mode of action of most antibiotics in bacteria is limited, and we know even less about the biochemical changes in drug-resistant mutants.…”

“…Skotnicki and Rolfe (1979) isolated neomycin-resistant mutants of R. trifolii strain Ti which were unable to grow on succinate as sole carbon source. The five mutants studied in detail had reduced ATPase activity and altered growth properties and were unable to synthesize ATP, all characteristics shown by E. coli unc mutants.…”