OVERVIEW OF NITROGEN FIXATION OF MARINE CYANOBACTERIA
- 海洋环境－已发表论文 
海洋生物固氮是海洋中氮循环的重要过程,其对海洋吸收CO2有着重要的影响。海洋固氮蓝细菌的种类和数量也有待进一步探明。现今的研究已表明,蓝细菌对海洋的氮平衡和生物生产有着重要的贡献。从海洋生物固氮的研究现状和研究方法着手,阐述了海洋生物固氮的意义,并重点对影响海洋生物固氮的因素、海洋蓝细菌生物固氮的生物化学和分子生物学机制等研究方面做了细致的综述,在此基础上提出了海洋生物固氮方面有待深入研究的科学问题,旨在为海洋生物固氮及氮的生物地球化学研究提供基础资料。Biological nitrogen fixation is much more important process in nitrogen cycle of the oceans than what was previously thought of. Nitrogen fixation may have an influence on capacity of the oceans to sequester carbon and the interactions between photosynthetic production of organic matter and nitrogen nutrient dynamics in the sea. A greater diversity of marine nitrogen fixation cyanobacteria has also been unknown and their quantitative significance remains to be determined. It is necessary to further study diversity and abundance of N_2-fixing cyanobacteria in order to resolve the issue of N_2 fixation in the ocean. A variety of approaches can reveal the the N_2-fixing ability of cyanobacteria, such as stable isotope tracer techniques to measure N_(2)-fixation rates; natural abundance stable isotope studies that indicate the contribution of N_2 fixation to organic matter; visual examination of microbial assemblages by microscopic approaches and genetic studies targeted at the genes for N_2 fixation. The application of classical microbiological, physiological and molecular techniques has drawn an increasingly complex picture of the composition and roles of marine cyanobacteria populations. Present study suggests that N_2 fixation could indeed be more widespread and important than those was previously assumed, and indicates that they might make a substantial contribution to the open ocean nitrogen budget. Significance of nitrogen fixation was discussed based on its recent results and protocols with specific emphasizes on its influencing factors, biochemical and molecular study. Then, scientific questions were launched for further research on marine nitrogen fixation, such as N_2-fixing picoplankton, the extent and diversity of N_2-fixing symbionts and genetic diversity of symbiotic cyanobacteria, aiming at offering basics for nitrogen fixation study.