南极近岸海域浮游细菌重要生态功能基因的多样性分析

发布时间：2018-06-07 10:53

本文选题：浮游细菌 + pufM　；参考：《集美大学》2014年硕士论文

【摘要】：浮游细菌在海洋初级生产力中占有重要地位，并且参与生物地球化学循环和能量流动过程。特定的功能基因在海洋微生物生态学中作为主要的标记基因可以用来分析特定类群的多样性。本研究对南极近岸两个相邻海湾——长城湾、阿德雷湾表层海水浮游细菌中的pufM，dmdA，dddP，GTAs(g5)等基因构建了克隆文库，分析了各基因的系统发育关系以及多样性。其中pufM编码好氧不产氧光合细菌的光反应中心亚基，dmdA和dddP编码参与DMSP（藻类的渗透调节物——二甲基硫丙酸内盐）代谢的相关酶，GTAs是一类广泛存在于红细菌类群中的来源于前噬菌体的基因簇。同时，本研究对比分析了南极样品与北极王湾海水样品中pufM和g5基因多样性的异同。结果表明： 1）南极近岸海域中的pufM基因主要来自α-变形菌中的红细菌目，少部分pufM基因来自β-变形菌或γ-变形菌的个别类群。整体上pufM基因的多样性较高，该基因在长城湾的多样性稍高于阿德雷湾。 2）南极近岸表层海水中的dmdA基因主要来自红细菌目的玫瑰杆菌支系，dddP基因的来源则包括α-变形菌的红细菌目和鞘脂单胞菌目、以及γ-变形菌的嗜冷杆菌（假单胞菌目），两种基因的多样性指数都较低，可能是由于所用引物对这些类群具有一定的偏好性。两个海湾中的dmdA基因多样性接近，，而长城湾dddP基因的多样性远高于阿德雷湾。 3）南极近岸表层海水的GTAs(g5)基因主要来自红细菌目，该基因在两个海湾的多样性指数接近且都很高。 4）南极近岸海域与北极王湾pufM和GTAs(g5)基因的对比研究表明，南极样品中的基因多样性稍高于王湾湾口（st1站），远高于王湾湾内（st5站）的多样性。这反映了环境及水文条件对两极海洋浮游细菌群落的影响，pufM多样性与硅酸盐和磷酸盐呈明显的正相关。 5）北极王湾样品中的pufM基因全部来自α-变形菌中的红细菌科，并且以硫杆菌属为主。根据南、北极的pufM多样性结果，我们推测所用的引物对特定类群可能具有较大的偏好性，还有较多的需氧不产氧光合细菌未被覆盖到。王湾样品中的g5基因全部来自红细菌目，这两种基因的多样性指数都是湾外高于湾内。南极近岸海域的特定生态功能基因，如光合基因、硫代谢相关基因、基因水平转移因子等多样性较高，说明以玫瑰杆菌支系为主的红细菌类群对极地海洋环境具有较强的适应能力。鉴于论文工作时间有限，本研究未能对相关基因在不同环境条件下（如温度，盐度，有机营养等）的表达水平进行研究。后续研究可以考虑采用荧光定量PCR及转录组学等方法对这些细菌的代谢表达情况进行检测，从而进一步认识这些细菌及其生态功能基因在南极低温海洋生态系统中的地位及作用。
[Abstract]:Planktonic bacteria play an important role in marine primary productivity and participate in biogeochemical cycle and energy flow. Specific functional genes can be used to analyze the diversity of specific groups as major marker genes in marine microbial ecology. In this study, a clone library was constructed for the genes of pufMmdAdddAdddPG5 from the surface water planktonic bacteria of the two adjacent coasts of the Antarctic coast-the Great Wall Bay and Adre Bay. The phylogenetic relationships and diversity of the genes were analyzed. Among them, pufM encodes the photo-reactive center subunit DMDA of aerobic non-oxygen-producing photosynthetic bacteria and dddP encodes the enzymes involved in the metabolism of DMSP (dimethyl sulphopropionate) metabolism, which is a class of widely existing Yu Hong bacteria. It is derived from the gene cluster of prophage. At the same time, the diversity of pufM and g5 genes in Antarctic samples and Arctic Bay seawater samples were compared and analyzed. The results show that: 1) the pufM gene in the Antarctic coastal waters was mainly from the order Rhodobacterium in 伪 -Proteus, and a few of the pufM genes came from the individual groups of 尾 -Proteus or 纬 -Proteus. The diversity of pufM gene was higher in the Great Wall Bay than in Adre Bay. 2) the dmdA gene in the surface waters of Antarctic coast mainly comes from the Rhizobium rugosa branch of RhoddP, which includes the order 伪 -Proteus red bacteria and the sphingomonas. The diversity index of the two genes were both low in P. pseudomonas and 纬 -Proteus, which may be due to the preference of the primers to these groups. The diversity of dmdA gene was similar in the two bay, but the diversity of dddP gene in the Great Wall Bay was much higher than that in Adre Bay. 3) the GTAsG5) gene of the Antarctic inshore surface water mainly comes from the order Rhodophyta, and the diversity index of this gene in the two bays is close and high. 4) the comparative study of pufM and GTAsG5) gene in Antarctic inshore waters and Arctic Bay shows that the genetic diversity in Antarctic samples is slightly higher than that in Wangwan Bay Kou st1 station and far higher than that in Wang Wan Bay. This indicates that environmental and hydrological conditions have a significant positive correlation with silicate and phosphate. 5) all the pufM genes in the samples from the Royal Bay of the Arctic were derived from the red bacteria family of 伪 -Proteus, and the dominant genus was Thiobacillus. Based on the results of pufM diversity in the North and South, we speculate that the primers used may have a greater preference for specific groups, and more aerobic non-aerobic photosynthetic bacteria are not covered. All of the g5 genes in the samples of Wangwan were from the order Rhodobacterium. The diversity index of these two genes was higher than that in the bay. Specific ecological functional genes, such as photosynthetic genes, sulfur metabolism-related genes, gene level transfer factors, and so on, are highly diverse in Antarctic coastal waters. The results showed that the Rhodobacterium species, which mainly belonged to Rosebacterium, had strong adaptability to polar marine environment. Due to the limited working time of the thesis, the expression level of related genes under different environmental conditions (such as temperature, salinity, organic nutrition, etc.) has not been studied in this study. Further studies may consider the use of fluorescent quantitative PCR and transcriptome methods to detect the metabolic expression of these bacteria. The status and role of these bacteria and their ecological function genes in Antarctic cryogenic marine ecosystem are further understood.
【学位授予单位】：集美大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：Q178.53

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