The Use of ¹⁵N

Rhizobium and Legume Root Nodulation
Leguminous Plants
The Discovery of Symbiotic Nitrogen Fixation
Rhizobium Classification
Cultural Characteristics
Genetics
Flavonoids Induce Nodualation
Novel Approaches to Extend Root Nodulation
Ecology
Infection
Lectins
Structure of the Nodule
Function of the Nodule
Nitrogenase Hydrogenase Interrelationship
Stem Nodulating Legumes
Factors Affecting Nodulation
Temperature and Light
Hydrogen Ion Concentration
Mineral Nutrition

The Use of ¹⁵N

The Use of ¹⁵N
While acetylene reduction test offers a rapid though indirect way of measuring nitrogenase activity and thus the ability of a biological system to fix atmospheric nitorgen, any critical evaluation of results must pass the ¹⁵N test. The technique formulated by Burris and Wilson in 1957, involves the use of ¹⁵N as a tracer. The amount of nitrogen fixed by a system is determined as the percentage increase of the tracer in samples incubated with the labelled gas.

An enrichment of 0.015 or greater atom per cent ¹⁵N in the sample (expressed as 0.015 atom per cent excess) is usually taken as an indication of nitrogen fixation. This method has been used extensively in the analyses of nitrogen fixation in whole cells and in cell-free extracts. The technique is time consuming and requires the use of expensive mass spectrometer and ¹⁵N tracer but is 10³ times more sensitive than the conventional Kjeldahl method.

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Index >> Rhizobium and Legume Root Nodulation >>The Use of 15N

The Use of 15N

Index >> Rhizobium and Legume Root Nodulation >>The Use of ¹⁵N

The Use of ¹⁵N