We are interested in getting rhizosphere bacteria with plant growth-promoting activities. We got hundreds of bacterial colonies from environmental samples and we must now evaluate nitrogen fixation in them. Does anyone know selective microbiological methods for these activities?
You could perform acetylene reduction assays in vitro or quantify nifH genes from your colonies. An example of how to carry out acetylene reduction assays in vitro is given in the attached file (in Spanish). Good luck!
First of all you grow all bacteria on general medium (eg. LB), after adequate growth take 1 ml broth and centrifuge it to remove media constituents, wash the cell three time by 1 ml 0.85% NaCl to remove completer N-present in inoculated media. Resuspend the pellet in 0.85% NaCl and put drop of inoculants on N-free media. If bacteria grows than it is N-fixing bacteria, but you have to confirmed finally by etylene reduction assays.
You can try acetylene reduction assay for measuring nitrogen fixation by any microbes. Wherein depending upon nitrogenase activity certain amount of acetylene will be converted to ethylene which can be measured using the technique of gas chromatography.
Hi all,
I must go step by step. I have almost a thousand bacteria isolated from soil, endosphere and rhizosphere of rice plants of Venezuela. Also cyanobacteria from water layer. We look for the ability to grow in nitrogen-deficient media of soil and rhizosphere bacteria. My question was addressed in this regard.
Subsequently, the ability to produce plant hormones and siderophores will be checked too.
All this with the purpose of selecting bacterial candidates for the development of rice biofertilizers.
Any thoughts, suggestions or ideas about this?
Thank you very much for yours answers!
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