Nitrogen Fixation In Presence Research Articles

Synthesis of nitrogenase by Paenibacillus sabinae T27 in presence of high levels of ammonia during anaerobic fermentation.

Biological nitrogen fixation is usually inhibited by fixed nitrogen. Paenibacillus sabinae T27, a Gram-positive, spore-forming diazotroph, possesses high nitrogenase activity and has 3 copies of nifH (nifH, nifH2, nifH3), a copy of nifDK, and multiple nifHDK-like genes. In this study, we found that P. sabinae T27 showed nitrogenase activities not only in low (0-3 mM) concentrations of NH4+ but also in high (30-300 mM) concentrations of NH4+, no matter whether this bacterium was grown in a flask or in a fermenter on scale cultivation. qRT-PCR and western blotting analyses supported that Fe protein and MoFe protein were synthesized under both low (0-3 mM) and high (30-300 mM) concentrations of NH4+. Liquid chromatography-mass spectrometry (LC-MS) analysis revealed that MoFe protein was encoded by nifDK and Fe protein was encoded by both nifH and nifH2. The cross-reaction suggested the purified Fe and MoFe components from P. sabinae T27 grown in both nitrogen-limited and nitrogen-excess conditions were active. This is the first time to report that diazotrophs show nitrogenase activity in presence of high (30-300 mM) concentrations of NH4+. Our study will provide a clue for studying the mechanisms of nitrogen fixation in presence of the high concentration of NH4+. KEY POINTS: • P. sabinae T27 can synthesize active nitrogenase in presence of high levels of ammonia. •Fe and MoFe proteins of nitrogenase purified in absence of ammonia are the same as those purified from the high concentration of ammonia. • Fe protein is encoded by nifH and nifH2, and MoFe protein is encoded by nifDK.

Microbial fixation of nitrogen in presence of lanthanum sulphate with sodium molybdate

The effect of lanthanum sulphate together with 100 micrometer of sodium molybdate show that there is considerable increase in nitrogen fixation and carbon consumption in the culture medium of nitrogen-fixing Azotobacter species A1 and A2, isolated from Allahabad soil. But these combination decrease the nitrogen fixation and carbon consumption in case of another species, Azotobacter A3, of the same soil.

Microbial fixation of nitrogen in presence of sodium tungstate

The effect of sodium tungstate in the culture media of three different species of Azotobacter, isolated from Allahabad soil, was studied. It was observed that the presence of tungstate in the culture media of bacterial sample A2 and A3 decreased the fixation of nitrogen, except in the bacterial sample A1.

Effect of Uranyl Acetate on Microbial Fixation of Nitrogen in Presence of Lanthanum Sulphate

100 μM of uranyl acetate increased the fixation of nitrogen in presence of 25 μM of lanthanum sulphate in the culture media. Further increase of lanthanum sulphate in the culture media, having 100 μM of uranyl acetate, shows a decrease to different extents in the three samples of microorganisms. The bacterial sample A 3 shows this decrease to a large extent. 100 μM Uranylazetat erhöhten bei Anwesenheit von 25 μM Lanthansulfat in Kulturmedien die Stickstoffbindung von Azotobacter . Eine weitere Erhöhung an Lanthansulfat ergab bei den drei Azotobacter -Stämmen eine Abnahme der N-Bindung in unterschiedlichem Ausmaße. Azotobacter A 3 zeigte diese Abnahme am ausgeprägtesten.