电化学联用技术研究微生物的胞外电子传递机制

胞外电子传递(EET)是指氧化还原反应所产生的电子在微生物细胞内和细胞外的电子受体/电子供体之间互相转移的过程,这一过程伴随着能量和物质的转化。阐明EET机制是提高微生物能量和物质转化效率的基础,为元素的生物地球化学循环、金属防腐以及生物电化学系统的应用等提供理论支撑。电化学技术作为研究电极/溶液界面电子转移的简便、有效方法,在研究微生物的直接电子传递和间接电子传递机制中发挥了重要的作用,也促进了EET机制的研究从宏观层面到微观层面不断深入。本文综述了研究微生物EET机制所涉及的电化学联用技术(包括微电极、扫描电化学显微镜、电化学联用光学显微镜和光谱电化学等);详细介绍了这些电化学联用技术的功能和优势;重点阐述了这些电化学联用技术如何推动着EET机制的研究,从宏观的生物膜层面到微观的单个微生物细胞、蛋白和分子层面不断深入;展望了新的电化学联用技术在EET研究领域的应用前景。国家重点研发计划项目项目(No.2017YFA0206500);;国家自然科学基金项目(No.21777155,21773198,U1705253,21621091)资助~

扫描电化学显微镜用于研究生物膜微环境的电子传递

生物电化学系统(BESs)的核心是生物膜在电极/溶液界面的电子传递反应,研究生物膜微区环境中的电子传递有助于阐明微生物的胞外电子传递(EET)机制,从而有针对性地提高BESs中的电子转移效率。微生物的EET机制包括直接电子传递和间接电子传递,由于生物膜组成复杂,含有多种分泌物、胞外聚合物等,常规电化学方法只能从生物膜宏观层面研究EET机制,无法有效区分这两种电子传递途径的贡献。本文采用电化学循环伏安方法研究了电子穿梭体二茂铁甲醇(FcMeOH)与希瓦氏菌(Shewanella)相互作用的界面过程;基于扫描电化学显微技术构建了穿透模式,通过微电极介导FcMeOH与Shewanella反应,收集仅来自间接电子传递途径产生的电流,同时测定了Shewanella在电极/溶液界面的氧化还原性质和空间分布。本论文将电化学扫描探针显微技术应用于EET的研究,从物理化学角度揭示微生物在代谢过程中与外界的电子传输机制。国家重点研发计划项目(2017YFA0206500);;国家自然科学基金(21777155,21773198,U1705253,21621091)资助~

K/T界线的研究进展——兼论元素演化与恐龙灭绝的可能关系

通过总结近一二十年来K/T界线的研究进展和恐龙绝灭的相关假说,认为前人在K/T界线和恐龙灭绝的研究方面确实取得了很大的成果,但同时,大多数的研究都是集中在对灾变大环境的求证上.只有少数学者注意到Co、Cr、Ni、Mn、V等这些在界线处变化较大的元素同时也是生物必需的微量元素,而另外一些异常元素(如REE、Pb、Sr等)也可能对生物的正常生理机能产生重要影响,这些元素的异常变化很可能与恐龙灭绝存在着一定的关系.但这方面的系统研究还相当缺乏,今后应加强元素的生物机能和与生命活动密切相关的元素在K/T界线附近的演化与恐龙灭绝的关系等方面的研究

Study on the differences of root spatial distribution characteristics of Phragmites australis in two different water-salt habitats in the Yellow River Delta

In order to study the growth differences of Phragmites australis, especially the differences of root ecological characteristics, between the tidal and fresh water habitats of the Yellow River Delta, two typical habitats of P. australis in tidal and fresh water habitats were chosen, and the electrical conductivity (EC) and pH of different soil layers were measured; the height, density, biomass of stem, leaf, main and fibrous root and ion content in different soil layers of P. australis were also analyzed. The results showed that the EC of surface soil (0-10 cm) was higher than that of the lower soil in both habitats and the minimum EC was tested in 20-30 cm soil layer. However, with the increase of soil depth deeper than 20-30 cm, the EC value increased and the pH decreased. The mean density and height of P. australis were (20.805.93) stem·m~(-2) and (35.7016.01) cm in tidal area, (309.60 39.15) stem·m~(-2) and (91.48 13.09) cm in fresh water habitat, separately. In terms of biomass allocation, the proportion of the main root, fibrous root, stem and leaf of P. australis in tidal and fresh water habitats were 79.70%, 11.88%, 6.79%, 1.64% and 66.77%, 8.76%, 18.54%, 5.92%, respectively. The main and fibrous root biomass of P. australis in fresh water habitat was mainly concentrated in 0-30 cm and 0-10 cm(68.1838.99) g·m~(-2) soil layer, respectively. And the main root biomass of P. australis in tidal water area was mainly concentrated in 20-3 0cm (146.57109.94) g·m~(-2) soil layer. After analyzing the ion content of roots in two habitats, we found the average content of Na~+ and K~+ in the main root of P. australis from tidal water habitat were (6.381.56) mg·g~(-1) and (1.080.17) mg·g~(-1) respectively, and the distribution of Na~+ and Cl- had a significantly positive correction (P<0.01). The average contents of these two ions in the main root of P. australis in fresh water habitat were (2.820.56) mg·g~(-1) and (3.931.10) mg·g~(-1) respectively. The results show that P. australis can adjust the height, density and biomass allocation of different organs and the distribution of ions to adapt to the different salt-water environment, which is the typical adaptation mechanism of P. australis in high-salt areas