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【目的】通过模拟水稻土淹水过程,探讨地杆菌科(Geobacteraceae)群落结构和相对丰度随淹水时间的动态变化特征,揭示其群落结构和相对丰度变化与微生物Fe(Ⅲ)还原的内在联系。【方法】提取水稻土淹水培养1 h、1 d、5 d、10 d、20 d和30 d后的微生物总DNA,构建地杆菌科16S rDNA克隆文库,采用PCR-RFLP方法分析地杆菌科的群落结构和多样性变化特征,通过Real-time PCR技术测定地杆菌科相对丰度的动态变化。采用厌氧泥浆培养方法,测定水稻土中Fe(Ⅱ)产生量变化。【结果】供试水稻土中,微生物Fe(Ⅲ)还原过程在淹水培养初期变化明显,培养20 d后达到稳定期,最大铁还原潜势为10.16 mg/g,最大反应速率为1.064 mg/(g.d),最大反应速率对应的时间为4.84 d。α多样性指数显示,水稻土中地杆菌科的多样性随淹水时间延长呈现波动性变化,淹水5 d和20 d处理出现2个峰值,而淹水10 d和30 d处理的多样性明显减小。β多样性指数表明淹水过程中群落结构存在明显差异。不同淹水时间共产生了10种地杆菌科优势类型,分别属于Clade 1和Clade 2。Real-time PCR结果表明,地杆菌科与总细菌16S rDNA丰度的比值在淹水培养1 d时最小(1.20%),而20 d时达到最大值(4.54%)。【结论】淹水培养的水稻土中,地杆菌科微生物的多样性和相对丰度的动态变化与微生物Fe(Ⅲ)还原过程密切相关。
【Objective】 The objective of this study was to investigate the dynamic changes of the structure and relative abundance of Geobacteraceae communities with time of flooding by simulating the process of flooding in paddy soils to reveal the changes of community structure and relative abundance with microbial Fe (Ⅲ) reduction inner relationship. 【Method】 The 16S rDNA clone library of Geobacterraceae was constructed by submerged culture of paddy soil for 1 h, 1 d, 5 d, 10 d, 20 d and 30 d. The genomic DNA of the soil was analyzed by PCR-RFLP The community structure and diversity of the changes in the characteristics of the Geobacillus family by Real-time PCR determination of the relative abundance of the dynamic changes. Anaerobic mud culture was used to determine the change of Fe (Ⅱ) production in paddy soil. 【Result】 The results showed that the Fe (Ⅲ) reduction process in the paddy soils changed significantly during the initial flooding period and reached the stationary phase after 20 days. The maximum iron reduction potential was 10.16 mg / g and the maximum reaction rate was 1.064 mg / (gd), the maximum reaction rate corresponds to 4.84 d. α diversity index showed that the diversity of Geobacteridae in paddy soil fluctuated with the prolongation of flooding time, with two peaks at 5 d and 20 d after flooding, and 10 and 30 d after flooding Significantly reduced. β diversity index showed that there was a significant difference in community structure during flooding. A total of 10 dominant species of Geobacteriidae were produced at different flooding times, belonging to Clade 1 and Clade 2, respectively. The results of Real-time PCR showed that the ratio of 16S rDNA abundance of the genus Bacillus and total bacteria was the lowest (1.20%) at 1 day and reached the maximum (4.54%) at 20 days. 【Conclusion】 The dynamics of microbial diversity and relative abundance in the geobacteriaceae in flooded paddy soil is closely related to the reduction process of microbial Fe (Ⅲ).