Measurement of nitrogenase activity, Biology

Measurement of Nitrogenase Activity

There are various methods to find out whether an organism is a N2-fixer or not. If an organism can grow in normal atmosphere without any provision of a nitrogen source like nitrate or ammonia, one infers the organism to be a N2-fixer. It is important to mention here that N2-fixer heterocysts cyanobacteria or Rhizobium-legume system are known to grow without any supply of fixed nitrogen. The other more reliable method is the incorporation of 15N isotope into cellular nitrogen containing compound which can be estimated in a mass spectrometer. This method is very costly and is, therefore, not easily accessible for day-to-day measurement of nitrogenase activity and N,-fixation. The most extensively used method for measuring nitrogenase activity is the acetylene reduction method. The method consists of incubating the N2-fixing system with about 10% acetylene for a period of 10 to 30 min during which nitrogenase converts acetylene into ethylene depending on its efficiency.

Gas samples are then taken out by syringe from the reaction sample and the acetylene reduced is assayed by injecting the gas sample into a gas chromatograph which separates quantitatively acetylene and ethylene and thus provides easy quantitative assay of ethylene. Nitrogenase catalysed reduction of acetylene to ethylene is not accompanied by reduction of proton to molecular hydrogen as happens in the reduction of N2 to NH­3. The reduction of acetylene to ethylene involves two electrons and if one wants to equate the amount of ethylene produced with the amount of N2 fixed then the amount of ethylene has to be divided by a factor of 4 to find out the optimum level of N2-fixing activity of nitrogenase.

Posted Date: 1/17/2013 5:16:21 AM | Location : United States







Related Discussions:- Measurement of nitrogenase activity, Assignment Help, Ask Question on Measurement of nitrogenase activity, Get Answer, Expert's Help, Measurement of nitrogenase activity Discussions

Write discussion on Measurement of nitrogenase activity
Your posts are moderated
Related Questions
What are the uses of squid fins? Fins are used by squids to move at low speeds. Their siphon is used when they require moving quickly.

describe the two scientific models for evolution (gradualism, punctuated equilibrium)

Density Independent Factors Density independent factors are the extrinsic factors which tend to regulate the density of a population in ways that are not correlated with its


Q. Show Nutrition guidelines for prevention of heart disease? Nutrition guidelines for prevention of heart disease as suggested by WHO are highlighted. Details regardin

Psychological Problems Failure to fulfill the patient's expectations and failure to gain the patient's acceptance and satisfaction constitutes a psychological failure. It is hi

Explain the Bioelectrical impedance Analysis (BIA)? The difficulty of measuring total body water (TBW) by Isotope Dilution Method led to the search of Bioelectrical Impedance A

Improvement of Soil Aeration Soil organisms greatly improve soil structure and facilitate aeration. Root decay leaves the soil riddled with channels, and the burrowing of worm

Explain risk factors and their role in cad ? The concept of risk factors constitutes a major advance for developing strategies to prevent CVD. The Framingham Heat Study played

is cnidaria having both interacellular & extracellular digestion?