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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
Thesis Advisor董俊德
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
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
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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