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摘要：本试验以高效降解乙草胺的菌株Sphingomonas sp. DC-6为材料，通过响应面法进行发酵培养基优化，验证该菌株液体发酵最佳发酵条件。主要采用海藻酸钠固定化包埋生物炭与菌株Sphingomonas sp. DC-6制备固定化微球，研究并对比了固定化微球和游离菌株的乙草胺降解能力。结果表明，培养基优化后的条件下，发酵罐液体培养提高了生物量和产酶量，发酵48 h生物量及酶活均为培养基优化前的1.22倍；确定了固定化微球的最佳制备条件：海藻酸钠浓度为10 g/L，生物炭含量为0.5%，菌体含量为2%，CaCl2浓度为10 g/L。固定化微球60 h对30 mg/kg乙草胺溶液的降解率为99.54%，是游离菌株的1.49倍；固定化微球重复利用3次后乙草胺降解率仍达到55.11%。这将为该菌工业化生产以及进一步应用于农药降解提供可靠的理论基础。26211
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毕业论文关键词：发酵；固定化；乙草胺；降解率
Fermentation, preparation and application of acetochlor degrading bacteria Sphingomonas sp. DC-6
Abstract：In this study, Sphingomonas sp. DC-6 was used as the strain, which can effectively degrade acetochlor. First the fermentation medium and conditions was optimized by response surface method, and then it was fed-batch cultured in a 7.5-l bioreactor. Alginate-activated carbon immobilized microspheres (AACM) were mainly prepared through immobilized biosorption of activated carbon and Sphingomonas sp. DC-6 by sodium alginate. The acetochlor-degrading performance of AACM and free strain were studied and compared. Results indicated that the biomass and enzyme production were increased under the optimal fermentation conditions. The biomass and enzyme activity after fermenting 48 h were 1.22 times of those before the optimization of medium. In addition, the optimal preparation conditions of AACM were determined as 10 g/L of alginate, 0.5% of activated carbon, 2% of optimal seed bacteria and 10 g/L of CaCl2. The degradation rate of immobilized microspheres for 30 mg/kg acetochlor solution in 60 h reached 99.54%, which was about 1.49 times higher than that of the free bacterial strain. Besides, after alginate-activated carbon immobilized microspheres were recycled for 3 times, and the ending degradation rate still reached 55.11%. This project will provide a reliable theoretical basis for the industrial production of strain Sphingomonas sp. DC-6 and another application approach for pesticide degradation.
Key words: fermentation；immobilization；acetochlor；degradation rate
目 录
摘要 1
关键词 1
Abstract 1
Key words 1
引言 1
1 材料与方法 2
1．1 材料 2
1．1．1 供试菌株 2
1．1．2 培养基 2
1．1．3 主要试剂与材料 2
1．1．4 主要仪器 2
1．2 方法 2
1．2．1 菌种平板活化 2
1．2．2 种子液及摇瓶培养基的培养 2
1．2．3 发酵条件优化验证 2
1．2．4 发酵罐液态发酵验证 3
1．2．5 制备菌制剂 3
1．2．6 联合固定化 3
1．2．7 固定化微球保存 3
1．2．8 乙草胺水解酶的酶活测定 3
1．2．9 乙草胺含量标准曲线的制作 4
1．2．10 乙草胺降解效果检测 4
1．2．11 乙草胺最大降解量测定 4
2 结果与分析 4
2．1 菌株活化与菌落形态 4
2．2 优化发酵条件摇瓶验证 5