[Studies on fermentation conditions of cytokinin produced by rhizobia strain 4012a]

The conditions of cytokinin fermentation of the rhizobia strain 4012a were detected by the ELISA. The results indicated that the optimal medium for cytokinin production by strain 4012a was composed of glucose 10 g/L, (NH4)2SO4 1.0, K2HPO4.3H2O 0.6, MgSO4.7H2O 0.1, CaCl2.2H2O 0.4, FeCl3.6H2O 0.04, Na2MoO4.2H2O 0.1 mg/L, calcium pantothenate 100 micrograms/L, adenine 200 mg/L. When strain 4012a was grown in 250 ml flask containing 50 ml of the medium on the rotary shaker (150 r/min) at 27 degrees C for 96 h, the yield of CTK 908 micrograms/L culture solution was obtained. It displayed bioactivity kinetin equivalents (KE) 1 mg/L medium with the radish cotyledon expansion test.