氟乐灵降解细菌D8的分离、鉴定与降解特性的研究

发布时间：2018-01-05 15:25

  本文关键词：氟乐灵降解细菌D8的分离、鉴定与降解特性的研究　出处：《塔里木大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： 氟乐灵 分离鉴定 蜡状芽孢杆菌 生物降解 降解途径

【摘要】：氟乐灵是一种广泛使用的二硝基苯胺类选择性芽前除草剂,主要用于甜菜、棉花、番茄等40多种作物及果园、林业苗圃等防除一年生禾本科杂草及部分双子叶杂草。因具有广谱性、性质和效果稳定、持效期长等特征,在世界范围内得到广泛的推广及使用,但其具有淋溶性差的特点,在土壤中能被土粒吸附而积聚在表土层,不易被雨水冲刷流失或淋溶至心底土层,残留在土壤中,少量的氟乐灵在土壤中残留可达两年之久,且对作物的出苗率和生长有影响,对生态环境和后茬作物都有一定的危害。本文针对氟乐灵残留污染问题研究其微生物降解技术,采用稀释分离培养法筛选氟乐灵高效降解菌,选取降解能力最优的一株菌株进行形态特征、生理生化特性和16S r DNA序列分析,确定其系统发育地位;通过单因素实验研究其最适降解条件;使用HPLC-MS分别对氟乐灵发酵液和降解菌株作用下的氟乐灵发酵液进行化学组分进行结构分析,探究降解菌株对氟乐灵的降解途径。主要研究结果如下:(1)以连作15年以上棉田土壤为材料,采用直接稀释涂布法分离得到1株能够降解氟乐灵的细菌D8,通过其形态特征、生理生化特性和16S rDNA同源性序列分析,鉴定菌株D8为蜡样芽孢杆菌(Bacillus cereus)。(2)通过单因素实验测得菌株D8降解氟乐灵的最适底物浓度为50.00 mg/L、接种量为4.00%、外加氮源为浓度0.10%的酵母浸粉、温度37℃、pH为5,在上述条件下培养3天时菌株对氟乐灵的降解率达59.89%以上。(3)利用安捷伦C-18反向色谱柱,柱温为30℃,流动相A相为纯净水,B相为甲醇,流速1 mL/min进行全波长扫描紫外检测。在同一条件下,使用HPLC-MS分别对氟乐灵发酵液、蜡状芽孢杆菌作用下的氟乐灵发酵液进行化学组分分析及鉴定,发现蜡状芽孢杆菌降解氟乐灵的可能降解途径为氟乐灵脱烷基、脱氨基、硝基还原和环化反应,主要的降解产物有2-乙基-7-硝基-1-丙基-5-三氟甲基苯并咪唑、2-乙基-7-硝基-5-三氟甲基苯并咪唑和3-硝基-5-三氟甲基苯胺。
[Abstract]:Trifluridine is a widely used selective presprout herbicide with dinitroaniline which is mainly used in more than 40 crops and orchards such as sugar beet cotton tomato and so on. Annual grasses and some dicotyledonous weeds have been widely used in the world because of their broad spectrum, stable properties and effects, long duration of effect and so on. However, it has the characteristics of poor leaching solubility, it can be adsorbed by soil particles and accumulated in the surface soil layer, it is not easy to be washed away by Rain Water or leaching to the bottom of the soil, remaining in the soil. A small amount of trifluridine remained in the soil for up to two years and had an effect on the emergence rate and growth of crops. In this paper, the microbial degradation technology of fluryl residue pollution was studied, and the dilution separation culture method was used to screen the high-efficiency fluryl degrading bacteria. A strain with the best biodegradability was selected for morphological, physiological and biochemical analysis and 16s r DNA sequence analysis to determine its phylogenetic status. The optimum degradation conditions were studied by single factor experiment. HPLC-MS was used to analyze the chemical components of the fermenting broth and the broth under the action of the degrading strain respectively. The main results were as follows: 1) the soil of cotton field for more than 15 years was used as the material. A strain of bacteria D8 was isolated by direct dilution coating method and its morphological, physiological and biochemical characteristics and 16s rDNA homology were analyzed. The strain D8 was identified as Bacillus cereusus. The optimum substrate concentration of the strain D8 was 50.00 mg/L. The inoculation amount was 4. 00 and the concentration of nitrogen was 0.10%. The temperature was 37 鈩，

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