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摘要：土壤微生物具有制造有机营养、抑制病害、解除毒害的作用，因此其与农作物的生长有着紧密的联系。本文针对农田土壤中优势细菌，进行分子鉴定，为解析徐州铜山新区农田土壤中的微生物菌落提供实验数据。首先采集徐州铜山农田土样，通过分离筛选获得2株优势细菌菌株，编号分别为B和T，细胞形态均为杆状，革兰氏染色阳性，有芽孢。2株细菌菌株经过16S rRNA基因的PCR扩增与测序，分别获得长度为1396bp和1516bp有效序列，GENBANK登录号分别为JX486705和JN216845，利用Clustalx 1.8 软件和MEGA 4.0软件对其分类学地位进行研究，表明B属于芽孢杆菌属，菌株B与Bacillus circulans亲缘关系最近，由此可推断菌株B属于芽孢杆菌属（Bacillus），暂命名为Bacillus sp.T；菌株T为新菌种，将其称为Bacillus sp.B。通过研究青椒种子在两株菌株B、T处理下其萌发情况，表明青椒种子被两种菌的培养上清液处理后均有不同程度的抑制作用。研究结果为探究土壤细菌对种子萌发的影响提供了实验数据。39127
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毕业论文关键词：优势细菌，16S rRNA，PCR，种子，发芽率，发芽势
Molecular identification of two dominate strains of bacteria from paddy soil and their effects on seeds germination of Capsicum frutescens
Abstract：Soil microorganisms have the functions of creating organic materials, inhibiting diseases and relieving poisons. As a result, soil microorganisms are closely related to the growth of vegetables. The paper focused on the molecular identification of the dominant bacterial strains in farmland soil, in order to provide experimental data of the soil bacteria in Xuzhou Tongshan New District. First of all, soil samples were collected from farmland of Xuzhou Tongshan New District. After isolating the dominant bacteria in the soil, pure strains numbered strain B and stain T were finally got. The isolates were both Gram- positive, spore-forming rods. After PCR amplification and sequencing, the 16S rRNA genes of strain B and strain T were acquired and their nucleotide sequences were determined. To investigate the systematics ranks of strain B and starin T further more, the software of Clustalx 1.8 and MEGA 4.0 were used to analyze and phylogenetic tree was constructed. The result is that, strain B and strain T belong to genus Bacillus. And strain B was identified as Bacillus circulans with 100% identity. This paper also investigated the effects of soil bacteria on germination of Capsicum frutescens seeds. The results showed that effects of bacterial strains B and T on seeds germination of Capsicum frutescens were different. The results afford the experimental data for seeds germination by soil bacteria.
Key words: Dominant bacteria; 16S rRNA; PCR; seeds; germination rate; germination tendency
目录
引言 1
1 材料与方法 2
1.1 供试材料 2
1.1.1土样 2
1.1.2培养基 2
1.1.3蔬菜种子 2
1.2 方法 2
1.2.1 分离筛选土壤中的细菌 2
1.2.2 菌体形态观察 2
1.2.3 细菌总DNA的提取 2
1.2.4 16S rRNA的PCR 扩增 3
1.2.5 PCR 扩增产物胶回收 3
1.2.6 16S rDNA与T载体的连接 3
1.2.7 测序 4
1.2.8 发育树的构建 4
1.2.9 优势细菌对蔬菜种子萌发探究 4
2 结果与分析 4
2.1 细菌的菌落形态与细胞形态 4
2.2 16S rRNA基因序列的PCR 扩增与序列分析 4
2.3 系统发育树的构建与分析 5
2.4 细菌B对青椒种子萌发的影响 6
2.5 细菌T对青椒种子萌发的影响 6