Adsorption and anti-ultraviolet light characteristics of the protoxin from Bacillus thuringiensis on montmorillonite,kaolinite, zinc oxide and rectorite |
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Authors: | Xueyong Zhou Jianbao Gao Shouwen Chen Bujiang Wang |
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Institution: | 1. Department of Food Science , Tianjin Agricultural University , Tianjin, P.R. China;2. College of Chemical Engineering and Technology , Wuhan University of Science and Technology , Wuhan, P.R. China;3. College of Chemical Engineering and Technology , Wuhan University of Science and Technology , Wuhan, P.R. China;4. State Key Laboratory of Agricultural Microbiology, National Engineering Research Center of Microbial Pesticides , Huazhong Agricultural University , Wuhan, P.R. China;5. Department of Food Science , Tianjin Agricultural University , Tianjin, P.R. China |
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Abstract: | The adsorption, desorption and anti-ultraviolet light characteristics of the protoxin from Bacillus thuringiensis strain WG-001 on montmorillonite, kaolinite, zinc oxide and rectorite were studied. The protoxin was easily adsorbed onto minerals and the adsorption reached equilibrium within 0.5–1.0 h (except for rectorite). The adsorption isotherms of protoxin at different concentrations in sodium carbonate buffer (pH 9) followed the Langmuir (R 2 >0.97) and Freundlich (R 2 >0.95) equations. The maximum amounts of protoxin adsorbed were in the order: montmorillonite>rectorite>znic oxide>kaolinite. In the range of pH from 9 to 11 (carbonate buffer), the protoxin adsorbed decreased with increasing pH. The adsorption was not significantly affected by the temperature between 5 and 45°C. Both free and adsorbed protoxin were toxic to larvae of Heliothis armigera. The LC50 value of free and adsorbed protoxin on montmorillonite, rectorite, zinc oxide and kaolinite were 14±1.16, 1.76±0.31, 2.94±0.71, 4.78±2.08 and 1.91±0.91 µg mL?1, respectively. After 1 h of ultraviolet irradiation, the LC50 of the above samples increased by 41.4, 19.3, 16.3, 125.9 and 62.3%, respectively. The desorption of adsorbed protoxin in water ranged from 30.1 to 64.9% and from 18.5 to 48.7% in carbonate buffer. |
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Keywords: | Bacillus thuringiensis protoxin minerals adsorption insecticidal activity ultraviolet light |
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