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造礁石珊瑚共附生固氮微生物多样性及固氮活性研究; Study on the Diversity of Nitrogen-fixing Microbes Associated with Coral and the Activity of Nitrogen Fixation
杨清松
Subtype硕士
Thesis Advisor董俊德
2016
Degree Discipline生物工程
Keyword造礁石珊瑚 生物固氮 微生物多样性 氮循环 厌氧氨氧化
Abstract珊瑚礁生态系统是生物多样性和生态价值最高的海洋生态系统之一。由于全球气侯变化和人类活动影响,全球珊瑚礁面临退化压力。珊瑚是珊瑚虫与共生藻及大量共附生微生物的共生体,珊瑚共附生微生物在参与珊瑚的营养供给和疾病抵抗等方面有重要功能。在寡营养海域,珊瑚共附生固氮微生物在为珊瑚共生体保障氮素供给方面起到了重要作用。研究珊瑚共附生固氮微生物多样性及其固氮活性对环境变化的响应,对珊瑚保育具有重要意义。以春季和夏季采自三亚鹿回头海域的三种珊瑚为研究对象,研究其共附生固氮微生物的丰度和群落结构的变化。十字牡丹珊瑚共附生固氮微生物的丰度和群落结构组成没有显著的季节性变化。稀杯盔型珊瑚和橙黄滨珊瑚共附生固氮微生物的丰度和群落结构存在显著的季节性差异。环境中硝酸盐和铵盐与珊瑚中固氮微生物的群落结构组成的变化有显著的相关性。珊瑚共附生固氮微生物可能通过调节其群落结构组成及丰度来参与珊瑚共生体的季节适应性机制。以三亚和西沙的冬季和夏季的造礁石珊瑚为研究对象,运用乙炔还原法测定其生物固氮活性。结果表明造礁石珊瑚固氮活性相对较低,瑚瑚中具有较高丰度和多样性的固氮菌可能不完全在珊瑚中发挥固氮作用。珊瑚固氮活性的季节性差异都不显著;不同珊瑚物种的固氮活性有显著差异。位于西沙寡营养条件下的珊瑚的固氮活性显著高于三亚的高营养盐环境的珊瑚固氮活性,近岸水体较高的营养盐可能会抑制珊瑚的生物固氮活性。固氮酶基因文库分析表明澄黄滨珊瑚在异常增生病化过程中伴随着珊瑚共附生固氮微生物的多样性增加,以及珊瑚共附生固氮微生物的优势类群由绿菌门到蓝细菌门的转变,及外源性固氮微生物比例的增加,揭示珊瑚共附生固氮微生物可作为珊瑚的健康状态评价和病化风险评估的指标。
Other AbstractCoral reef ecosystem is one of the most high biodiversity and valuable marine ecosystem. Affected by blobal climate change and human activities, , coral reef is at the risk of worldwide extinction. Reef-building coral is the holobiont consist of the collective community of coral host, symbiotic algae and vast of microbes. The microbes in coral play an important role in nutrients-support and anti-disease. Coral associated diazotroph is recognized to provide extra nitrogen nutrients to coral holobiont in oligotrophic ocean. Research focus on the diversity and activity of coral associated diazotroph and their adoptive mechanism to the variation of environment are valuable for coral protection. The diversity and community structure of diazotroph associated with corals from Sanya were collected in spring and summer. In contrast with coral Pavona decussata, both Galaxea astreata and Porites lutea showed significantly seasonal changes in the diazotrophic communities and nifH gene abundance. Moreover, that seasonal variations of both the abundance and the community structure in Porites lutea are higher than in Galaxea astreata. The change of concentration of ammonium and nitrate will affect the coral associated diazotrophic community structure. Coral associated diazotrophs may contribute to the coral holobiont's adaptive response to the seasonal environmental variation by adjusting the abundance and community structure of themselves. The nitrogen fixation activity of coral at Sanya and Xisha in winter and summer was analysed using Acetylene Reduction Assay(ARA). The nitrogen-fixation activity of corals is relatively low, and the nitrogen-fixation activity of Pocillopora damicomis, Acropora gemmifera and Porites lutea between spring and summer are not significantly different. But the activity of nitrogen-fixation in different coral species are significantly different. The corals from Xisha, where is in the oligotrophic waters, have higher nitrogen-fixation activity than those from Sanya. The higher nutrients concentrations of sea water may restrain the activity of nitrogen-fixation in coral. In the process of coral disease of growth anomaly in Porites lutea, the biodiversity of diazotroph raised, and the dominant group shifted from Chlorobi to Cyanobacteria, and the proportion of exogenous diazotraph increased. Diazotroph in coral contributed to the response of coral holobiont to coral disease process. The results indicated that the biodiversity of diazotrophs in coral might be an indicator of coral healthy status. With the application of microarray named GeoChip 5.0, we found almost all the nitrogen cycle process including nitrogen fixation, N assimilation, ammonification, denitrification, assimilatory N reduction and dissimilatory N reduction in coral. And some of the genes related to nitrogen cycle are reported in the coral holobiont for the first time. Especially, the anaerobic ammonium oxidation was first detected in the coral holobiont. It is positively corrected between the abundance of anaerobic ammonium oxidation associated genes and the concentration of ammonia in the environment. The process of ANAMMOX in coral need to be further studied.
Document Type学位论文
Identifierhttp://ir.scsio.ac.cn/handle/344004/14745
Collection学位论文(硕士)
Recommended Citation
GB/T 7714
杨清松. 造礁石珊瑚共附生固氮微生物多样性及固氮活性研究, Study on the Diversity of Nitrogen-fixing Microbes Associated with Coral and the Activity of Nitrogen Fixation[D],2016.
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