Study On The Spray Drying Technology Of Bacillus Thuringiensis And The Formulation Of Insecticidal Protein Adsorption On Nano-materials

The effects of inlet air temperature, outlet air temperature and atomizing air pressure on the spores and crystal protein content of Bacillus thuringiensis were studied. The spores and crystal protein content decreased with the drying temperature and their sensitivity to the temperature was different. The pseudo-z value ( a temperature increase needed for one log cycle reduction) of spores and crystal protein content caused by inlet air temperature was 250C and 740C respectively; the pseudo-z value of spores and crystal protein content caused by outlet air temperature was 72.7C and 270 C respectively. The activation energy of spore and crystal protein calculated by the outlet air temperature was 112.24 kJ mol-1 and 123.88 kJ mol-1 respectively. No obvious changes were found for the spores and crystal protein content as the atomizing air pressure increased from 0.10 MPa to 0.25 MPa. The filler gave some protection to the spores and crystal protein from heat.The effects of inlet air temperature, liquid feed rate and atomizing air pressure on the yield, moisture content, crystal protein content, spores and lethality of Bacillus thuringiensis powder during the spray drying of Bacillus thuringiensis fermentation liquor were studied by an orthogonal experiment. The results of variance analysis indicated that the extent of influence of factors on the yield of Bacillus thuringiensis was in the order: atomizing air pressure> inlet air temperature> liquid feed rate; and on the moisture content, crystal protein content, spores and lethality of Bacillus thuringiensis was in the order: inlet air temperature> liquid feed rate> atomizing air pressure. The mathematical models describing the relationship between spray drying parameters and the yield, moisture content, crystal protein content, spores and lethality of Bacillus thuringiensis were established. The influential trends of operation parameters to the product properties could be shown directly by these models, and the performance of the production could be controlled by adjusting these parameters. The optimum spray drying conditions determined by these mathematical models were: inlet temperature 180C, liquid feed rate 60 ml min", atomizing air pressure 0.1 MPa. The results of the validation experiment showed that these mathematical models established by the orthogonal experiment were reliable. Available data showed that this important post-treatment technology was seldom reported up to now.The effects of centrifugation and micro-filtration concentration of the fermentationliquor on the spores, crystal protein content, titer and rheological properties were studied. After concentration of the fermentation liquor, the density, viscosity, solid content, spores, crystal protein content and titer increased, but the titer yield decreased. The addition of supernatant or concentrated supernatant to the concentrated fermentation liquor leaded to the increase of the titer yield. By comparison of both concentration methods, the micro-filtration concentration was more favorable for increasing the titer yield of the concentrated fermentation liquor than the centrifugation concentration. The titer, spores and crystal protein content of spray dried powder of concentrated fermentation liquor were higher than those of spray dried powder of fermentation liquor without concentration, but the titer yield decreased if the concentration times was more than 2.5. The spray drying of fermentation liquor added by filler without concentration was a effective method for recovering bioactive components.The yield of spray dried powder increased if .the fermentation liquor added by 0.5%~1.0%(w/v) filler, however, the yield of spray dried powder decreased as the filler content was more than 3.0%(w/v). The results of correlation analysis showed that there was a highly negative correlation between the density of filler and spray drying yield, the higher the density, the lower the yield; as far as the same filler was concerned, the finer the particle size, the higher the yield. The above laws can give...