Growth and nitrogen fixation dynamic of azotobacter chroococcum in nitrogen-free and omw containing medium

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2003

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Sarıbay, Gül Fidan

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Olive Mill Wastewater (OMW), by-product of oil industry, is a dark liquid with a characteristic fetid smell, bitter taste and bright appearance; having a high pollution potential, creating serious problems in countries producing olive oil. Azotobacter chroococcum as a Nitrogen-fixing bacteria can bioremediate OMW, by degrading its toxic constituents. With the help of this detoxification process OMW can be used as biofertilizer. In this study, the dynamics of growth and nitrogen fixation at different physiological conditions and nutrient requirements of A. chroococcum in chemically defined N-free medium was determined. These parameters were cultivation conditions such as pH, temperature and aeration and some additives such as inorganic salts, boric acid and nitrogen. Consequently, the maximum cell concentration were obtained when A. chroococcum was grown at neutral pH, 35?C, 150 rpm and in medium supplemented with manganese salt at 0.01% concentration. The maximum nitrogen fixation products were attained when A. chroococcum was grown under the same conditions except at pH 8. Further, bioremediation of OMW by A. chroococcum was examined. When A. chroococcum was cultivated in OMW containing basal medium at 10% OMW concentration, a cell density 12 times higher than in the OMW free medium was achieved. Also, it was found to have maximum increase in extracellular protein concentration (112 mg/l) at 10% OMW containing medium and maximum increase in ammonia concentration (9.05 mg/l) at 5% OMW containing medium.

Subject Keywords

Azotobacter, Azotobacter chroococcum, Nitrogen fixation, OMW, Bioremediation

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http://etd.lib.metu.edu.tr/upload/1098961/index.pdf
https://hdl.handle.net/11511/13859

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

G. F. Sarıbay, “Growth and nitrogen fixation dynamic of azotobacter chroococcum in nitrogen-free and omw containing medium,” M.S. - Master of Science, Middle East Technical University, 2003.