BBC - GCSE Bitesize: Mutualism and parasitism
students will culture nitrogen-fixing bacteria from root nodules of leguminous plants. Be ready with a fire blanket in case of an ethanol fire. Another important group of nitrogen-fixing bacteria is that of the cyanobacteria, found in association with a large variety of higher and lower plants, fungi and. Peas, beans and clover are leguminous plants. They have colonies of nitrogen- fixing bacteria in nodules attached to their roots. The plants gain nitrates from the .
The resulting barium cyanide could be reacted with steam yielding ammonia. In Adolph Frank and Nikodem Caro decoupled the process and first produced calcium carbide and in a subsequent step reacted it with nitrogen to calcium cyanamide.
The Ostwald process for the production of nitric acid was discovered in Frank-Caro process and Ostwald process dominated the industrial fixation of nitrogen until the discovery of the Haber process in Haber process Equipment for a study of nitrogen fixation by alpha rays Fixed Nitrogen Research Laboratory, Artificial fertilizer production is now the largest source of human-produced fixed nitrogen in the Earth 's ecosystem. Ammonia is a required precursor to fertilizersexplosivesand other products.
The most common method is the Haber process. This highly efficient process uses natural gas as a hydrogen source and air as a nitrogen source.
However, such research has thus far failed to even approach the efficiency and ease of the Haber process.
Many compounds react with atmospheric nitrogen to give dinitrogen complexes. Guided by the example of nitrogenase, this area of homogeneous catalysis is ongoing, with particular emphasis on hydrogenation to give ammonia. Procedure Take care with ethanol and be prepared to deal calmly with small fires.
Take precautions to make sure living cultures remain closed. Preparation a Calculate the quantity required.
Prepare just enough agar medium for the investigation cm3 for normal depth in a 90 mm Petri dish. Any surplus will keep for months in tightly-sealed screw-top bottles if sterile and stored out of direct sunlight.
See Standard technique Making up nutrient agars. See Standard technique Pouring an agar plate.
Nitrogen-fixing bacteria in root nodules of leguminous plants
Students should wear eye protection. Investigation a Leave one plate unopened as a control. Choose a length of root with pink nodules and cut off a 1 cm portion using a scalpel Note 4. Hold the root with forceps; rinse off adhering soil using tap water.
Put the pipette into your discard pot.
Nitrogen-fixing bacteria in root nodules of leguminous plants | Nuffield Foundation
Transfer enough sterile water to cover the base of a sterile Petri dish, using a sterile Pasteur pipette and teat. Keep the pipette sterile for later use by resting it under the lid of another sterile Petri dish.
Use the forcepts to transfer the root to the sterile water and rinse off the ethanol. Repeat this twice more with fresh sterile water. Add the portion of root using sterile forceps.
Macerate mash the nodules with the forceps or a sterile glass rod to produce a milky fluid. Flame the loop again. See also Standard technique Making a streak plate. Do not open the plate. See Incubating and viewing plates. Teaching notes Rhizobium can fix nitrogen only in conditions such as those prevailing in a root nodule.
These are very difficult to reproduce in the laboratory. Therefore the aim is to remove all microbes from outside nodule by chemical sterilisation.
Then to grow Rhizobium by inoculating a fixed nitrogen-containing culture medium with a sample taken from inside the root nodule.
Rhizobium fixes gaseous nitrogen from the air into compounds plants can use to help them grow.