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水稻土是非常复杂又典型的生态系统,分析淹水培养过程中水稻土细菌的丰度和群落结构变化规律,可以客观反映水稻土中细菌群落结构信息,为深入探讨水稻土细菌微生物对稻田的影响和在生态系统中的作用(营养元素转换、重金属还原与抑制甲烷生成过程等)提供实验基础与理论依据。作者采用淹水非种植水稻土微环境模式系统,提取水稻土淹水培养1 h和1、5、10、20、30、40、60 d后的微生物总DNA,利用Real-time PCR和PCR-DGGE(denaturing gradient gel electrophoresis)技术检测了淹水培养过程中细菌丰度与群落结构的变化。结果表明:淹水水稻土中细菌的丰度在1 d时最大,并在40 d到达第二个峰值,说明淹水过程改变了细菌的丰度。基于16S rRNA基因V3区的DGGE图谱分析显示,淹水过程中细菌的群落结构发生了演替性变化:r-策略生存的细菌仅存在于淹水初期;k-策略生存的细菌存在于淹水后期;r-和k-策略共生存的细菌存在于整个淹水过程中,淹水后期k-策略的细菌占据优势。淹水培养过程中优势种群多样性指数大体呈现先上升后减小的趋势。主成分分析(PCA)将淹水处理过程分成几类不同的生境,反映出中、后期细菌群落结构较为稳定;测序结果表明,32个优势条带所代表的细菌分别属于厚壁菌门、绿弯菌门、拟杆菌门、变形菌门和酸杆菌门,且与来自不同地域的水稻土、其他类型土壤、活性污泥以及湖泊沉积物等生态系统的细菌关系密切。
Paddy soil is a very complex and typical ecosystem. Analyzing the abundance and community structure of paddy soils during the flooding process can objectively reflect the bacterial community structure information in paddy soils. In order to further investigate the effects of paddy soil microbes on paddy fields Impact and role in the ecosystem (nutrient conversion, heavy metal reduction and methane production process inhibition) to provide the experimental basis and theoretical basis. The authors used the micro-environmental model system of non-planted paddy soils to extract the total microbial DNA of submerged paddy soils cultured for 1 h and 1, 5, 10, 20, 30, 40 and 60 d. Real-time PCR and PCR- DGGE (denaturing gradient gel electrophoresis) technique was used to detect the changes of bacterial abundance and community structure during the flooding culture. The results showed that the abundance of bacteria in flooded paddy soil reached the maximum at 1 d and reached the second peak at 40 d, indicating that the flooding process changed the abundance of bacteria. Based on the DGGE analysis of V3 region of 16S rRNA gene, the community structure of bacteria evolved in succession during flooding: r-strategy survived bacteria existed only in early flooding period; k-strategy survived bacteria existed in flooding At the later stage, the bacteria that r- and k-strategy coexisted existed throughout the flooding process, and k-strategy bacteria dominated the latter stage of flooding. The diversity index of dominant species in flooding culture generally showed the trend of increasing firstly and then decreasing. The principal component analysis (PCA) divided the flooding process into several different habitats, reflecting the stable bacterial community structure in the middle and late stages. Sequencing results showed that the 32 dominant bands belonged to Firmicutes, Campylobacter, Bacteroidetes, Proteobacteria and Acidobacteria, and are closely related to bacteria from paddy soils, other types of soils, activated sludge and lake sediments from different regions.