Thirty-one bacterial type ferredoxins were examined by means of the parsimony method for their phylogenetic implications. The results show reasonable relationships in that photosynthetic, thermophilic, and desulfovibrio groups are identifiable; but a number of interesting anomalies occur. These include a methanogen sequence that clusters among the desulfovibrios. There are several differences f...

Mutants of Azotobacter vinelandii that fix N(2) in the presence of excess NH(4) (+) have been isolated. A mutant that was unable to synthesize component I and component II of nitrogenase was spontaneously reverted to the N(2)-fixing phenotype. Of 21 revertants picked, 7 revertants were not as sensitive as the wild type to repression. A derepressed mutant is as sensitive as the wild type to grow...

Acetylene is a slow-binding inhibitor of the Ni- and Fe-containing dimeric hydrogenase isolated from Azotobacter vinelandii. Acetylene was released from hydrogenase during the recovery from inhibition. This indicates that no transformation of acetylene to another compound occurred as a result of the interaction with hydrogenase. However, the release of C2H2 proceeds more rapidly than the recove...

During the enzymic reduction of N2 to NH3 by Mo-nitrogenase, free hydrazine (N2H4) is not detectable, but an enzyme-bound intermediate can be made to yield N2H4 by quenching the enzyme during turnover [Thorneley, Eady & Lowe (1978) Nature (London) 272, 557-558]. In contrast, we show here that the V-nitrogenase of Azotobacter chroococcum produces a small but significant amount of free N2H4 (up t...

A transconjugant of Azotobacter chroococcum Mac 27 tagged with lac Z(A. chroococcum Mac27 L) was found to possess high levels of β-galactosidase activity constitutively. Further, the lac Z marker was found to be stably integrated into the chromosome of the A. chroococcum Mac 27 and did not have any adverse effect on growth, nitrogen fixation and excretion of ammonia. A quick method to determine...

To better understand the influence of environmental conditions on the adsorption of extracellular chromosomal DNA and its availability for natural transformation, the amount and conformation of adsorbed DNA were monitored under different conditions in parallel with transformation assays using the soil bacterium Azotobacter vinelandii. DNA adsorption was monitored using the technique of quartz c...

Azotobacter vinelandii nitrogenase Fe protein (Av2) provides a rare opportunity to investigate a [4Fe-4S] cluster at three oxidation levels in the same protein environment. Here, we report the structural and vibrational changes of this cluster upon reduction using a combination of NRVS and EXAFS spectroscopies and DFT calculations. Key to this work is the synergy between these three techniques...

An amino acid sequence is proposed for the cytochrome c4 from the bacterium Azotobacter vinelandii strain OP. It is a single polypeptide chain of 190 residues, with two sets of haem-attachment cysteine residues at positions 14/17 and 119/122. Proteins with similar sequences are also present in denitrifying pseudomonads. There is similarity in sequence between the two halves of the cytochrome c4...

The study of the metabolism of Azotobacter has been generally approached from the standpoint of the r6le of this organism in the nitrogen cycle in Nature, but the fact that the ability to fix free nitrogen is regulated by the presence or absence of combined nitrogen in the medium has not been given serious attention although it is made plain in the works to be cited. Bejierink and Van Delden (1...

A pot experiment was carried out during 2009 and 2010 to study the field performance of blue pine seedlings inoculated with selected species of bio-inoculants under nursery conditions .The experiment was laid in Completely Randomized Design with three replications which comprised of seven inoculants (Azotobacter sp., Azospirillum sp., Pseudomonas fluorescens, Bacillus subtilis, Pisolithus tinct...