The Mössbauer spectra of MoFe-protein of Azotobacter vinelandii, as isolated under dithionite and taken at temperatures from 125 K to 175 K, are the sums of four resolved quadrupole doublets. Our results indicate that the currently accepted interpretation of these doublets can be questioned. Our data reduction method converts the Mössbauer transmission spectra to source lineshape deconvolved ab...

Though almost 20 years have elapsed since the introduction by the writer of the method of nutrient-solution purification for studying trace-element requirements of plants, no application of this procedure to studies with bacteria has as yet been made. For reasons readily apparent, it has long seemed desirable to the writer to obtain data affording a direct comparison of the effects of this tech...

The yield, nutrient uptake and cost efficacy of Chlorophytum. borivillianum were studied using dual inoculation with AM fungi (Glomus fasciculatum) and Azotobacter chroococcum. The experiment was conducted for two consecutive years with two levels of chemical fertilizers as F1(N-P-K : 24-24-32 kg ha) and F2 (N-P-K : 30-30-40 kg ha). Inoculation of bioinoculants encouraged results; the fresh tub...

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...

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...