青岛潮间带趋磁细菌的垂直分布特征及与环境因子的关系

趋磁细菌是一类能够沿着磁力线运动的革兰氏阴性细菌, 主要生活在淡水和海洋的有氧-无氧过渡区。本调查通过对青岛汇泉湾潮间带沉积物柱状样分层样品中趋磁细菌的计数和沉积物理化因子的分析, 研究了趋磁细菌的垂直分布特征及其与环境因子的关系。结果显示趋磁细菌以趋北型的趋磁球菌占优势, 主要分布环境的氧化还原电位为179.7～-107.0 mV, 为弱还原-还原性质, 最大丰度(94～169个/cm³)出现在氧化还原跃层(表层下5～9cm黄-黑沙界面处), 暗示有氧-无氧过渡区; 趋磁细菌的垂直变化趋势与粒径、含水率、硫酸盐的变化趋势基本一致。     

荣成月湖潮间带单细胞趋磁细菌的多样性研究

Marine magnetotactic bacteria were collected from the intertidal sediments of Yuehu Lake(China), where their abundance reached 103–104 ind./cm3. Diverse morphotypes of magnetotactic bacteria were observed, including cocci and oval, vibrio-, spirillum-, rod-, elliptical-, handle- and bar-shaped forms. The magnetococci were the most abundant, and had flagella arranged in parallel within a bundle. The majority of magnetosomes were arranged in one, two or multiple chains, although irregular arrangements were also evident. All the results of high-resolution transmission electron microscopy(HRTEM) analysis show that magnetosome crystals were composed of Fe3O4, and their morphology was specific to particular cell morphotypes. By the 16 S r RNA gene sequence analysis, we found fourteen operational taxonomic units(OTUs) which were related to magnetotactic bacteria. Among these, thirteen belonged to the Alphaproteobacteria and one to the Gammaproteobacteria.Compared with known axenic and uncultured marine magnetotactic bacteria, the 16 S r RNA gene sequences of most magnetotactic bacteria collected from the Yuehu Lake exhibited sequence identities ranging from 90.1% to96.2%(97%). The results indicate that microbial communities containing previously unidentified magnetotactic bacteria occur in the Yuehu Lake.     

胶州湾海域表层沉积物细菌多样性

采用16S rDNA文库结合PCR-RFLP分析的手段,对胶州湾4个站位沉积物中的细菌多样性和群落特征研究分析。结果表明,沉积物中细菌种类丰富,最多包含分布于14个已知门类的细菌,和一些未被认知的序列;各站位沉积物中优势菌群均为变形菌门和酸杆菌门,其中γ-和δ-变形菌纲为变形菌门中的绝对优势类群,在4个文库序列中平均占42%和16.75%;此外,拟杆菌门、浮霉菌门和放线菌门的种类也较为大量存在。各细菌种群有较明显空间分布差异,可能与不同区域胶州湾环境条件相关。     

Characterization of dominant giant rod-shaped magnetotactic bacteria from a low tide zone of the China Sea

Magnetotactic bacteria are a group of Gram-negative bacteria that synthesize magnetic crystals, enabling them to navigate in relation to magnetic field lines. Morphologies of magnetotactic bacteria include spirillum, coccoid, rod, vibrio, and multicellular morphotypes. The coccid shape is generally the most abundant morphotype among magnetotactic bacteria. Here we describe a species of giant rod-shaped magnetotactic bacteria(designated QR-1) collected from sediment in the low tide zone of Huiquan Bay(Yellow Sea, China). This morphotype accounted for 90% of the magnetotactic bacteria collected, and the only taxonomic group which was detected in the sampling site. Microscopy analysis revealed that QR-1 cells averaged(6.71±1.03)×(1.54±0.20) m m in size, and contained in each cell 42–146 magnetosomes that are arranged in a bundle formed one to four chains along the long axis of the cell. The QR-1 cells displayed axial magnetotaxis with an average velocity of 70±28 mm/s. Transmission electron microscopy based analysis showed that QR-1 cells had two tufts of fl agella at each end. Phylogenetic analysis of the 16 S r RNA genes revealed that QR-1 together with three other rod-shaped uncultivated magnetotactic bacteria are clustered into a deep branch of A lphaproteobacteria.     

直接使用航摄底片进行飞行质量检查

通过对底片法与常规法检查流程的比较及对飞行质量的检查，论述了用航摄底片直接进行飞行质量检查的可行性，实践证明，利用底片法是一种行之有效的方法。