We have applied 57Fe nuclear resonance vibrational spectroscopy (NRVS) for the first time to study the dynamics of Fe centers in Fe-S protein crystals, including oxidized wild type rubredoxin crystals from Pyrococcus furiosus, and the MoFe protein of nitrogenase from Azotobacter vinelandii. Thanks to the NRVS selection rule, selectively probed vibrational modes have been observed in both orient...

The crystal structure of the bacterioferritin from Azotobacter vinelandii has been determined at 2.6 A resolution. Both the low occupancy of one iron ion in the dinuclear iron center and the deviation of its adjacent residue His130 from the center suggest migration of the iron ion from the dinuclear iron site to the inner nucleation site. The concerted movement of His130 and Glu47 may admit a d...

In recent years, it has become evident that [Fe-S] proteins, such as hydrogenase, nitrogenase and aconitase, require a complex machinery to assemble and insert their associated [Fe-S] clusters. So far, three different types of [Fe-S] cluster biosynthetic systems have been identified and these have been designated nif, isc and suf. In the present work, we show that the nif-specific [Fe-S] cluste...

Nitrogenase was isolated and purified from wildtype and a tungsten-resistant mutant (LM2) of Azotobacter vinelandii strain OP derepressed on medium containing 1-10 mM W. While the enzyme from the wild-type strain contained the polypeptides of the conventional enzyme, metal analysis of component 1 demonstrated the existence of one atom each of molybdenum and tungsten. Furthermore, the ESR spectr...

Spontaneous mutants of Azotobacter vinelandii defective for glucose utilization were selected as resistant to 5-thio-D-glucose. Mutant strains AM2, AM38, and AM39 exhibited longer generation times than the wild type when grown on glucose. Mutant strain AM2 also exhibited an altered Km and Vmax for glucose uptake. During acetate-glucose diauxie, glucose utilization in the 5-thio-D-glucose-resist...

Cyst germination in Azotobacter vinelandii ATCC 12837 was studied by using phase contrast and electron microscopy. Germination in this organism was accompanied by the formation of large cyst forms of two different types: giant cysts and cysts containing multiple central bodies. Previously, these two types have been reported only when yeast extract was added to the encystment medium. In this stu...

conclusions: it was concluded that increasing the concentration of zinc in the agricultural soil is harmful to beneficial microorganisms and reduces the soil fertility. a 20-ppm zinc concentration in soil is suggested to be optimal. background: zinc is an essential micronutrient used in the form of zinc sulfate in fertilizers in the agriculture production system. nitrogen-fixing microorganisms ...

Asymbiotic and associative diazotropic bacteria such as Azotobacter and Azosprillum, respectively are widely distributed in different rhizospheric and nonrhizospheric soils and help in growth and development of plants. Sixty two soil samples were collected from different crop rotations namely Rice-Wheat, Vegetables, Agro forestry and Grassland from the districts Chandauli, Jaunpur,Ballia, Ghazi...

abstract soil beneficial microorganisms such as plant growth promoting rhizobacteria (pgpr) are able to enhance plant growth. the research was conducted using a randomized complete block design as split plot factorial with three factors (nutrient management, azospirillum and azotobacter strains) .in this experiment the effect of azospirillum and azotobacter inoculation on yield and yield compon...

Detection of viable Azotobacter in soils stored in the laboratory for more than 10 years suggests that these bacteria can remain dormant in nature for prolonged periods of time. Studies of dried cultures show that cysts of A. vinelandii 12837 remain viable for at least 10 years, whereas vegetative cells do not survive for even 1 year under the same conditions.