荣成月湖潮间带趋磁细菌的周年变化与环境的关系及培养

	荣成月湖潮间带趋磁细菌的周年变化与环境的关系及培养
	杜海舰
学位类型	博士
导师	肖天
	2015-05-20
学位授予单位	中国科学院研究生院
学位授予地点	北京
学位专业	海洋生态与环境科学
关键词	趋磁细菌多细胞趋磁原核生物周年变化微生物培养月湖
摘要	月湖位于中国山东半岛东部，是一个典型的北方滨海瀉湖。在月湖的东北部潮间带表层沉积物中存在大量的趋磁细菌(Magnetotactic Bacteria, MTB)，包括多细胞趋磁原核生物 (Multicellular magnetotactic prokaryotes，MMPs)。目前已在这里发现的有桑葚型MMPs (spherical MMPs) 和菠萝型MMPs (ellipsoidal MMPs)。我们选择了这两类MMPs优势度各自显著的两个区域为调查取样点，分别标记为A点 (淡水流经区内) 和B点 (淡水流经区边缘)，对它们的丰度周年变化，及其与环境因子的关系进行了研究。同时我们通过改进培养基和培养方法对该区域的趋磁细菌进行实验室培养。两个取样点皆处于低潮区。样品采集于2012年9月至2013年12月期间，平均两周采集一次。相比较，A点环境因子的变化比B点剧烈。两种MMPs在两个点处的优势度存在差异，A点处桑葚型MMPs占优势，B点菠萝型MMPs占优势，这可能是由于它们各自适应环境能力不同。桑葚型MMPs拥有较强的适应能力，能够在变化剧烈的环境生存；而菠萝型MMPs对环境条件要求苛刻，需要一个更稳定的生存环境。两种MMPs丰度的周年变化显著，都是夏季与秋季高，冬季与春季低。但两种MMPs丰度达到最高峰的时间不同。桑葚型MMPs先于菠萝型MMPs到达最高峰，这可能是由于两种MMPs的适宜温度不同。菠萝型MMPs生存适于较宽温度范围，桑葚型MMPs适于在较高温度下生存。盐度、SO42-、总有机碳、总硫等因子可能对桑葚型MMPs的丰度变化影响较大；PO34-、SiO32-等因子可能对菠萝型MMPs丰度变化有影响。我们在实验室获得了两种趋磁球菌的培养株，它们都分离自荣成月湖潮间带，暂时命名为RO-1与RO-2。通过人工培养，在培养7天后两种细菌的浓度皆可达到106 ind./mL以上。 RO-1在光镜下观察呈卵球型，大小为1.91 ± 0.30 μm × 2.28 ± 0.44 μm；电镜下菌体内磁小体呈簇状分布，不成链，磁小体形态均为棱柱型，成分为Fe3O4；每个菌体有1-2束鞭毛，生于菌体两侧，由多条纤丝组成；运动轨迹为螺旋形，运动速度为58.8 ± 14.9 μm/s。 RO-2在光镜下观察亦呈卵球型，大小为1.17 ± 0.13 μm × 1.48 ± 0.17 μm；电镜下菌体内磁小体呈链状排列，多为一条链，少数存在两条链，磁小体形态均为棱柱型，成分为Fe3O4；每个菌体有1-2条鞭毛，生于菌体两侧；运动轨迹为螺旋形，运动速度为163.4 ± 61.8 μm/s。经过16S rDNA基因序列分析，RO-1与Uncultured bacterium clone XCQD60 (KM083512) 相似性最高，为96.7%。RO-2与Uncultured Magnetococcus sp. clone MRC-2 (KJ591588) 相似性最高，为98.0%；与MC-1的相似性为96.9%，与MO-1的相似性为93.4%。两种趋磁细菌均属α-变形菌纲，是未得到纯培养的新种。
其他摘要	Lake Yuehu is a shallow coastal lagoon located on the east side of Shandong Peninsula, China. Large numbers of magnetotactic bacteria (MTB) are found from the sediment of intertidal zone in the northern part of Lake Yuehu, including two morphotypes (spherical and ellipsoidal) of multicellular magnetotactic prokaryotes (MMPs). Two sites, marked as site A (in the area where a rivulet flows past) and site B (on the edge of the area where a rivulet flows past), were chosen according to their different type dominating at each site. Here their temporal distributions and their relationships with biogeochemical parameters were studied. Moreover, two novel marine magnetococci were cultured by use of modified media of other magnetotactic bacteria. The sample sites are located in low tide region. Samples were collected from sites A and B at approximately two-week intervals during ebb tides from September 2012 to December 2013. The variation in biogeochemical parameters was more pronounced at site A. Although two types of MMPs coexisted at both sites, their numbers were different; at most times spherical MMPs dominated at site A, while ellipsoidal MMPs dominated at site B. Geochemical analysis revealed that the environmental conditions at site A varied more than at site B. Compared with the widely distributed spherical MMPs, ellipsoidal MMPs seemed to prefer more stable habitats. The abundance of MMPs was high in summer and autumn, but low in winter and spring. Furthermore, the peaks in the numbers of the two types of MMPs were sequential, with the highest concentration of the spherical MMPs occurring prior to that of the ellipsoidal MMPs. This may be related to different optimal growth temperatures for the two types. Spherical MMPs prefer relatively higher temperatures than ellipsoidal MMPs. Salinity, organic matter, sulfur, sulfate et al. may regulate the variation in abundance of spherical MMPs, while phosphate, silicate et al. may influence the abundance of ellipsoidal MMPs. Two novel marine magnetococci, RO-1 and RO-2, which were from intertidal zone of Lake Yuehu were cultured. The concentration of these cocci can reach 106 ind./mL after 7 days’ culturation. The cells of strain RO-1 are roughly spherical, with a size of 1.91 ± 0.30 μm × 2.28 ± 0.44 μm. Magnetosomes arranged in a disorganized cluster and crystals are prismatic magnetite. Each cell had 1-2 flagellar bundles on the long hemisphere. We observed that RO-1 showed a helical trajectory and the average velocity of was 58.8 ± 14.9 μm/s. The cells of strain RO-2 are roughly spherical, with a size of 1.17 ± 0.13 μm × 1.48 ± 0.17 μm. Magnetosomes arranged in one chain (occasionally 2 chains) and crystals are prismatic magnetite. Each cell had 1-2 flagella, which were speculated to be within bundles, on the long hemisphere. We observed that RO-1 showed a helical trajectory and the average velocity of was 163.4 ± 61.8 μm/s. Phylogenetic analysis revealed that 16S rDNA gene sequences of strain RO-1 showed a maximum sequence identity with uncultured bacterium clone XCQD60 (KM083512) (96.7%). The sequence of strain RO-2 showed a maximum sequence identity with uncultured Magnetococcus sp. clone MRC-2 (KJ591588) (98.0%), and was 96.9% and 93.4% identical to MC-1 and MO-1, respectively. Two strains both belonged to the Alphaproteobacteria and were novel cultured magnetotactic bacteria.
学科领域	海洋生态与环境科学
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/22751
专题	海洋生态与环境科学重点实验室
作者单位	中国科学院海洋研究所
第一作者单位	中国科学院海洋研究所
推荐引用方式 GB/T 7714	杜海舰. 荣成月湖潮间带趋磁细菌的周年变化与环境的关系及培养[D]. 北京. 中国科学院研究生院,2015.

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