海草根际微生物与海草植株的互作效应

【目的】本文以三亚湾泰来草根际沉积物为主要研究对象,研究室内培养条件下泰来草根际沉积物微生物对于高温处理和海草定殖的响应。【方法】通过对培养过程中水体物理化学参数(如pH、溶解氧、磷酸盐、硝酸盐、亚硝酸盐和铵盐)的监测以分析环境因子的变化;16S rRNA扩增子测序研究微生物群落结构的动态响应;通过荧光定量分析16SrRNA基因丰度变化。【结果】研究表明高温处理组在培养35 d后海水中磷酸盐、硝酸盐、亚硝酸盐和铵盐含量以及pH均要高于模拟原位环境的对照组,高温处理组根际沉积物微生物丰度在培养过程中呈现先上升后降低的趋势,同时,高温处理组根际微生物中初始阶段由厚壁菌门(32.4%)、变形菌门(22.92%)和梭杆菌门(27.21%)占据优势,培养一段时间后,厚壁菌门和梭杆菌门大幅度减少,逐渐被蓝细菌门和放线菌门所替代,最终由变形菌门(51.1%)占据主导地位,其中,属于硫还原细菌的脱硫杆菌科(Desulfobacteraceae)和硫氧化细菌的螺杆菌科(Helicobacteraceae)的细菌丰度不断提高。【结论】揭示了海草的定殖会提高高温处理后沉积物的多样性,并塑造和改善其根际沉积物微生物群落组成。

Seagrass-microbial interactions in the rhizosphere

[Objective] This research aims to investigate the response of rhizosphere microbial community after seagrass transplantation to high temperature treated seagrass sediment in Sanya Bay.[Methods] The environmental parameters including pH, dissolved oxygen, phosphate, nitrate, nitrite and ammonium were measured. High-throughput sequencing and real-time quantitative PCR of the 16S rRNA gene were used to analyze the diversity, structure and abundance of microbial communities in the rhizosphere of seagrass Thalassia hemperichii.[Results] The concentration of seawater nutrients (phosphate, nitrate, nitrite, ammonium) and pH were significantly higher in high temperature treatment group after 35 days. The abundance of 16S rRNA gene increased firstly and then reduced with the time. In addition, Firmutes (32.4%), Fusobacteria (27.21%) and Proteobacteria (22.92%) were the dominant phyla in rhizosphere in high temperature treatment group at the beginning of incubation period. But Firmutes and Fusobacteria were then decreased and replaced by Cyanobacteria and Actinobacteria over time. Proteobacteria (51.1%) dominated the rhizosphere microbial communities in the final phase. Moreover, Desulfobacteraceae belonging to sulfate-reducing bacteria and Helicobacteraceae affiliated with sulfate-oxidizing bacteria increased over time.[Conclusion] Colonization of seagrass would improve the microbial diversity of high temperature treated sediment, shape and change the microbial communities in rhizosphere.