Question

You think you have nitrogen fixers in an anaerobic part of your Winogradsky column. You cap the column with 15N2 gas (a non-radioactive N isotope) and want to identify the active N2 fixers in this region of the column both metabolically and molecularly. Describe in detail the approach you would take to identify the active nitrogen fixers

Answer 1

The experiment will have to be carried out with three replications (biological replicates). Set up 3 identical columns that have been capped with
`15N_(2)` gas and incubate for up to 24 hours. This will allow the nitrogen fixing bacteria time to carry out the process of nitrogen fixation. Collect 100 g of sample of soil from each of the column and perform the acetylene reduction assay, which measures nitrogenase activity.

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