以沼渣为原料固态发酵生产Bt生物农药

    Solid state fermentation of biogas residues for production of Bacillus thuringiensis based bio-pesticide

    • 摘要: 沼渣是沼气工程中产生的副产物,由于其富含营养物质及微量元素,而广泛应用于农业,畜牧业,养殖业等方面。Bt生物农药是一类具有选择性和高效性的杀虫剂,但是由于其原料的成本较高从而限制了生物农药的发展,而沼渣中富含微生物所需要的各种养分并且价格低廉,因此该文以生产沼气后的沼渣为资源,运用固态发酵,探索了利用沼渣制备苏云金杆菌生物农药的可行性。首先对沼渣营养成分进行了分析,分析表明其营养物质丰富,适合苏云金芽孢杆菌的生长与增殖。其次对菌种的沼渣培养基进行了优化,优化后的培养基质量分数为:50%的沼渣添加35%啤酒糟,10%玉米粉,5%豆饼粉,并与常规培养基和单纯沼渣的发酵进程进行了对比。在优化培养基条件下,发酵48 h后,芽孢数达到5.23×1010 CFU/g,毒力效价为16 100 IU/mg。在传统培养基中芽孢数2.55×1010 CFU/g,毒力效价12 500 IU/mg,而在单纯沼渣中Bt产量及毒性为1.74×108 CFU/g,6000 IU/mg。采用沼渣发酵制备Bt生物农药与传统培养基比较,降低了36.3%的生产成本,且发酵性能优良,也为沼渣的利用寻找到崭新的途径。

       

      Abstract: Abstract: Biogas residue is the main byproduct from the biogas process. It has been widely used in agriculture and stockbreeding for its rich content of nutriments and microelements. Bio-pesticides derived from Bacillus thuringiensis are the most well-known biological agents for selective control of pest insects. However, the high cost of raw materials is one of the key factors hindering their development speed and scale. Recently, some cheap raw materials such as maize starch, wheat bran, rice straw and wastewater sludge have been successfully substituted for more expensive media. Biogas residue is renewable, low-cost, and is composed of organic material that contains the necessary nutritional elements to sustain the growth of microbes. In this study, Biogas residues were used as a substrate for bio-pesticides production by solid state fermentation. Principal component analysis of biogas residue indicated that it was well suited for the growth of Bacillus thuringiensis in the experiments. The culture medium recipe was optimized by the orthogonal test. Brewer's grain, corn meal, soybean cake power and mixed ions were chosen to carry out the study.The results showed that brewer's grain had the biggest effects on the growth of Bacillus thuringiensis and then followed the growth effects of corn meal, soybean cake power and mixed ions. Ultimately, the optimum media were 50% biogas residues, 35% brewer's grain, 10% corn meal, and 5% soybean cake power. This article compared the fermentation process among conventional media, only biogas residues media and the optimum media, under the optimized conditions. Spore counts of 5.23×1010 CFU/g and entomotoxicity of 16100 IU/mg were obtained after 48h fermentation, while 2.55×1010 CFU/g spore counts and 12500 IU/mg entomotoxicity were obtained in the conventional medium, and 1.74×108 CFU/g spore counts and 6000 IU/mg entomotoxicity were found in the only biogas residue medium. At last, by comparing the cost between conventional medium and the optimum media, the cost could be lowered by 36.3%. The present study proved the feasibility of using kitchen waste for the production of bio-pesticides, and it seemed to be a promising alternative for the use of conventional mediums to reduce the costs.

       

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