| Today people used a large number of chemical fertilizers and chemical pesticides in agricultural production, the problem of environment pollution is more and more serious. So, to find effective, environmentally friendly new alternative has become an inevitable , trend. Microbial fertilizer and microbial pesticides have many excellent features, such as nontoxic towards human and environment. They can partly or completely replace the chemical fertilizers and chemical pesticides, but how maintain the activity of the microbial in the period of produce and preserve of their formulations is a common problem. In this study, the death kinetics of the Bacillus subtilis 3-10 under different conditions was study, Optimization of the formulation of complex microbial fertilizer. In this study, we used poly-y-glutamic acid and gelatin as wall material to prepare the microbial microcapsules, and optimize the product conditions, and studied the resistance of the microbial microcapsules.Bacillus suhtilis 3-10 was the main object in this study, used mathematical model to study the death kinetics of microbial in different conditions It's non-isothermal lethal curve, isothermal lethal curve with different time treatment and different pH conditions can well fit the Slogistic model, Logistic model and the Boltzmann model, the correlation coefficient R2>0.99. The results showed that these models can well describe the cell's death, so it can be used to guide the research and production of microbial fertilizer.The optimized formula of compound microbial fertilizer:The chemical fertilizer contains (NH2)2CO, NaH2PO4 and K2SO4, which account 18±1% of the total weight(the molar ratio of (NH2)2CO, NaH2PO4 and K2SO4 is 1:1:1), Adding 30±2%,2×109 cfu/mL bacterial suspension, stirring and adjusting the pH 7.0, organic fertilizer account 50% (The ingredients of organic fertilizer contains wheat straw, rapeseed meal and hull, the weight proportion are 1:1:1), preparation compound microbial fertilizer and placed in oven at 80?treatment 10 min (the thickness are 5 mm or so). Compared with the control, maize seedlings which used compound microbial fertilizer which contains Bacillus subtilis 3-10 increased the plant height by 59.3%, increased root length by 43.1%, fresh weight was increased 54.6% and dry weight increased 63.6%, Compound microbial fertilizer which contains Bacillus subtilis 3-10 can save fertilizer over 20% significantly.In this study, the preparation conditions of poly-y-glutamic acid-gelatin microcapsules was optimized, The optimal conditions contains:the concentration of wall material 1.2%, pH 4.0, stirring speed 400 r/min, temperature 50?, proportion of poly-y-glutamic acid and gelatin 1:1, bacterial suspension 5-10%(concentration of Bacillus subtilis 3-102×1010 cfu/mL), formaldehyde 0.6 mL/g gelatin. In this conditions, the embed rate of microcapsules of Bacillus subtilis 3-10 was 94.2%.The preparation of poly-?-glutamic acid-gelatin microcapsules can significantly improve the ability of microbial resistance, under the UV radiation 80 sec, the spore survived in the microcapsules was 51.6%, the spore in suspension only 12.2%; treating 40 min in 90?, the spore only 31.9% survived in suspension, and 55.4% in microcapsule. This dates shows that poly-y-glutamic acid-gelatin microcapsules can enhance heat resistance of microbial cells. Heat treatment at extreme pH, the spore survival in microcapsule was higher than in cell suspension, with pH=3.0, at 90?,20 min, the survival rate of spore in microcapsule is 2.9 times which in cell suspension.As pot experiment showed that the growth promotion and anti-watermelon wilt of the Bacillus subtilis 3-10 are significantly. Compared with the control, the length of watermelon root was increased 54.60%, the length of stem increased 39.5%, dry weight increased 4.9%, the efficiency of poly-y-glutamic acid-gelatin microcapsules of Bacillus subtilis anti-watermelon wilt was 89.66%. |
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