In vitro cultivation of Nostoc commune Vauch. (Nostocaceae, Nostocales) and its nitrogen fixation potential
2005
Revalde, S.D. | Senires, G.S.M.B. | Sibi, S.S.c. | Largo, D.B.University of San Carlos, Talamban, Cebu City (Philippines))
Four different culture media, namely: Fogg's medium, Bg-11 [both prepared as formulated, less a nitrogen source (minus "N")], distilled water, and soil extract, were used for the in vitro cultivation of the cyanobacterium, Nostoc commune. The number of heterocysts, dry weight, and tissue nitrogen of three replicates from each culture medium were determined to assess the nitrogen fixation potential of N. commune grown in each medium. Results show that BG-11 medium minus N medium yielded the highest number of heterocysts (123) and percent tissue nitrogen (4.67%) while the soil extract medium yielded the least number of heterocysts (78) and percent nitrogen (3.41%). Nostoc grown on solid agar or suspended on liquid media proved ineffective in monitoring growth and determination of heterocysts due to unavoidable microbial contaminants. The use of cotton as solid substrate and sprayed only with the above nutrients prepared in liquid form proved more advantageous and solve the problem of contamination. The nitrogen fixation potential based on relationship between heterocyst formation, dry weight, tissue nitrogen and nitrogen limitation is discussed.
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