不产氧光能营养细菌在生物土壤结皮发育中的关键作用及其机制研究

Desertification is a major environmental problem and biological soil crust (BSCs) can promote the restoration of desertification. Microbes, possessing the key functions of carbon and nitrogen fixation or extracellular polysaccharide producing and etc., plays a vital role in the development of BSCs. Anoxygenic phototrophic bacteria (APB) have the related functions, but the role of APB in the development of BSCs and the mechanism is remain unknown at present. Therefore, this project will take Inner Mongolia deserts as the object and put research on the key functions and mechanism of APB in the development of BSCs: from two points of view (based on molecular biology methods and cultivation technology respectively), from four aspects (the relationship between APB community diversity and the ecological function, the influence of APB on the cyanobacteria growth, the inoculation of APB and different wavelengths of light on the BSCs development), to systematically explore the APB community diversity and the temporal-spatial distribution, compare the capabilities of the key functions of APB in carbon and nitrogen fixation and etc., and assay the influence of APB on the development of BSCs; finally to demonstrate explicitly the community diversity of APB, the key functions and mechanisms of APB in the development of BSCs, fully reveal the ability of APB in the desert restoration, and provide the scientific basis and technique support for the ecological restoration of the deserted soil. Based on the desert in Inner Mongolia and focused on the hot issue of the ecology and environment sciences, the project has remarkable regional and local characteristics, is promoting the level of local BSCs researches to be improved and the related researchers to be trained, and has a significant theoretical significance and practical application value.

荒漠化是一个重大环境问题，生物土壤结皮(BSCs)可遏制荒漠化。具有固碳、固氮或产胞外多糖等关键功能的微生物对BSCs的形成和发展起着关键作用。不产氧光能营养细菌(APB)具有相关功能，但目前APB在BSCs发育中的作用还不清楚。本项目以内蒙古荒漠为对象，研究APB在BSCs发育中的作用及机制：应用分子生物学和分离培养两种技术，从APB群落多样性与生态功能之间的关系、APB对蓝藻生长的影响、APB接种和波段不同的光照对BSCs发育的影响四个方面，系统研究和阐释内蒙古荒漠BSCs中APB群落多样性和时空分布，APB在BSCs发育中的关键功能、作用及机制，充分揭示APB资源及其荒漠化修复的能力，为荒漠化土壤的生态修复提供科学依据和技术支持。本申请项目聚焦于全球生态环境热点问题，立足内蒙古荒漠，具有明显的地区和地域特色，将促进地区BSCs研究发展和相关人才培养，具有重要理论意义和实践价值。

荒漠化是一个重大环境问题，生物土壤结皮(BSCs)可遏制荒漠化。具有固碳、固氮或产胞外多糖等关键功能的微生物对BSCs的形成和发展起着至关重要的作用。不产氧光能营养细菌(APB)具有相关功能，但以往缺乏BSCs中APB的相关研究报道。本项目以内蒙古荒漠BSCs中的APB为例，利用Mi-seq高通量测序的分子生物学方法和涂布划线分离培养技术，揭示BSCs中细菌和APB群落的时空分布特征和影响群落结构的环境驱动因子；以网络分析和结构模型等分析阐释APB群落多样性与生态功能之间的关系；以微宇宙模拟和接种验证APB对BSCs发育的影响。结果表明：APB在荒漠BSCs中的丰度较高（最多可达8%）、多样性高，存在许多未知的种类（以寡营养+光照刺激生长的分离培养方式获得10余株新种，其中有3个新属）、未报到过的功能（如在APB菌株B3发现卡尔文循环的固碳的基因组和生理证据；广泛存在于BSCs中的Hymenobacter的有固氮、解磷等植物促生功能，等等）；BSCs中的细菌和APB群落结构随经度变化而变化，土壤环境因子pH是决定因素；Methylobacterium等处于细菌和APB网络的核心节点，结构模型也显示与土壤有机质等关系密切，预示这些菌在BSCs发育中的作用重要；室内微宇宙和接种实验中，以近红外激活APB可显著加速BSCs的形成和发育，结皮厚度、有机质含量和微藻丰度相比对照分别增加高达24%、104%和1447%；耦合植物、磷钾矿粉的野外接种APB也加速了BSCs的发育，同时促进了植物的生长。这些结果预示，APB通过自身固碳、利用光能减少呼吸，以及促进藻类和植物生长等方式提高土壤有机质累积，同时具有的固氮和解磷等功能也为BSCs发育提供相关营养支持，表明APB有荒漠化修复的能力，为荒漠化土壤的生态修复提供科学依据和技术支持，具有重要理论意义和实践价值。