五大连池火山堰塞湖沉积物中趋磁细菌多样性、时空分布及磁性贡献

Magnetotactic bacteria (MTB), a diverse group of microorganisms with the ability to orient and migrate along geomagnetic field lines, are ubiquitous in aquatic environments. They have become one of the hottest research topics due to the existence of magnetosomes. The biodiversity and ecological function of MTB have attracted widespread attention. In this work, the MTB resources in Wudalianchi volcanic barrier lakes will be systematically investigated. MTB will be isolated by dilution plate method. Phylogenetic diversity and temporal-spatial distribution of MTB will be analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.The diversity in morphological types of MTB, magnetosome shapes and arrangements will be characterized by transmission electron microscopy (TEM). The relationship between environmental factors and the diversity of MTB will be analyzed by principal component analysis (PCA) and canonical correlation analysis (CCA). The magnetic properties of MTB and sediments will be comprehensively measured by vibrating sample magnetometer (VSM), superconducting quantum interference device (SQUID) and M?ssbauer spectroscopy analysis. Based on the research above, the information on germplasm, 16S rDNA and magnetism of MTB will be obtained; the community composition, dominant species variation and diversity of MTB in sediments of Wudalianchi volcanic barrier lakes will be clarified; the effects of lake location difference, seasonal succession, horizontal space shift and sedimental depth variation on the MTB distribution will be revealed; the role of MTB in the geochemical cycle of iron and sulfur will be understood; and the contribution of MTB to sediment magnetism will also be recognized. This work will provide new information for the study of volcano microorganisms and the development and utilization of MTB.

趋磁细菌（MTB）是一类广泛分布且能沿磁力线定位和运动的细菌，因能合成磁小体而成为当前的研究热点之一，其多样性及生态作用研究更受到广泛关注。本项目拟对五大连池火山堰塞湖MTB资源进行系统研究，采用稀释平板法分离MTB；通过PCR-RFLP分析MTB系统发育多样性及时空分布；通过透射电镜表征MTB形态多样性、磁小体形态和排列的多样性；应用PCA和CCA分析环境因子同MTB多样性的关系；利用振动样品磁强计、超导量子干涉仪及穆斯保尔谱仪解读MTB及沉积物的磁学特性。以获取MTB的种质、16S rDNA及磁学信息；阐明五大连池火山堰塞湖沉积物中MTB的组成、优势种变化及多样性，揭示湖体区位变化、季节演替、水平空间变化及沉积物垂直深度变化对MTB分布的影响；了解MTB在铁、硫地球化学循环中的作用，揭示MTB对沉积物磁性的贡献；为火山微生物研究及MTB开发利用提供新资料。

五大连池火山区是研究较小尺度上MTB多样性及其环境贡献的理想区域。项目分离获得Magnetospirillum属的菌4株，Magnetococcus属的菌6株，以及可产磁小体的铁氧化菌7株。五大连池火山堰塞湖分布着球形、杆形、梭形、空心球形和多细胞聚集体等多种形态的MTB。所有湖泊MTB的优势门均为Proteobacteria，而各湖泊MTB在属水平上差异较大，月牙泡与药泉湖优势菌属均为Crenothrix，二池和四池优势菌属均为Alphaproteobacteria，温泊、一池、三池、五池的优势菌属分别为Nitrospira.（16.21%），Magnetospirillum（31.28%），Staphylococcus（19.33%），Methylophilaceae（63.71%）。不同水体类型湖泊中MTB在水平尺度上分布差异显著，.Proteobacteria丰度由南至北降低，MTB在垂直尺度上分布也不同。同一水体类型不同湖泊中MTB在水平尺度上的分布显著差异，半封闭型水体MTB多样性随深度增加降低。Proteobacteria和Thaumarchaeota在水平和垂直尺度的门水平中占主导，Magnetococcus和Acinetobacter在水平和垂直尺度的属水平上占优势。三池、月牙泡和药泉湖的不同位点MTB的空间分布存在差异。Proteobacteria和Woesearchaeota_[DHVEG-6]在水平和垂直尺度的门水平上占主导。三池、月牙泡和药泉湖不同采样点MTB属水平上群落组成存在差异。MTB在水平尺度上主要受pH的影响，在垂直尺度上受亚铁、硫化物、全磷的影响最大。春夏季节变化对MTB在不同水体中的多样性和丰度影响明显，Proteobacteria，Acinetobacter等优势物种夏季比春季丰度更高。MTB对二池和四池的低频和高频频率磁化率的影响较为显著。在0-15000 Oe范围内，MTB对温泊、一池、二池沉积物常温磁性的影响趋势类似，对其余5个水体沉积物常温磁性影响趋势相同，其中MTB对温泊沉积物磁性贡献最大。MTB对月牙泡、药泉湖、五池沉积物低温磁性影响不显著，对四池和温泊的贡献较大。本项目为研究火山铁、硫元素循环，阐明五大连池火山微生物多样性，揭示MTB对沉积物磁性的贡献机制，以及开发利用MTB提供基础数据。