Starter Grant: Uncovering the Phylogenetic And Physiological Diversity of Soil Acidobacteria

属于酸杆菌门的细菌在土壤中普遍存在且丰富。尽管如此，我们对土壤酸细菌知之甚少，只有一小部分的门内的遗传多样性进行了调查和thephylogenetic关系的酸细菌类群还没有得到充分解决。此外，土壤酸杆菌的生理特性及其在土壤中的生态作用还很不清楚。其中一个主要原因是酸细菌在土壤培养物中的代表性很差，因为它们很难使用传统的培养策略进行培养。本研究的目的有两个：1）调查和描述土壤酸细菌的遗传多样性; 2）改进土壤酸细菌的体外培养方法，以评价其生理特性。为了达到这些目标，我们将从美国各地收集六种不同的土壤，并从提取的DNA中构建酸细菌特异性克隆文库，以描述土壤酸细菌的系统发育多样性。然后，我们将使用基于PCR的筛选方法来确定具体的条件，或一组条件，在此条件下，最有效地从土壤中培养酸菌。我们的目标是分离和培养那些从土壤克隆文库的结果中发现在所收集的土壤样品中数量丰富的酸细菌。由于我们以前的工作表明土壤酸细菌是强贫营养的，我们期望酸细菌可以在营养不良的培养基和延长的培养时间中得到最有效的培养。Oncesoil酸细菌可以在体外成功分离培养，并对其生理特性进行深入评价。通过这个项目，我们将大大扩展我们目前对土壤酸细菌的了解;我们将描述这个未被调查的类群的遗传多样性，通过获得纯培养分离物，我们可以开始研究土壤酸细菌的生态作用。该项目将为研究生提供常规微生物学（菌株分离和培养）和分子微生物学（rDNA序列分析）方面的培训。

Bacteria belonging to the phylum Acidobacteria are ubiquitous and abundant insoil. Despite this, we know very little about soil Acidobacteria; only a smallportion of the genetic diversity within the phylum has been surveyed and thephylogenetic relationships of acidobacterial taxa have not been adequately resolved. Inaddition, the physiological characteristics of Acidobacteria and their ecological roles insoil remain largely unknown. One major reason for this is that Acidobacteria are poorlyrepresented in soil culture collections as they are difficult to culture using traditionalculturing strategies. This project has two objectives: 1) to survey and describe thegenetic diversity of soil Acidobacteria, and 2) to improve methods for the cultivation ofsoil Acidobacteria in vitro so their physiological characteristics can be assessed. Tomeet these objectives, we will collect six distinct soils from across the United States andbuild acidobacterial-specific clone libraries from extracted DNA to describe thephylogenetic diversity of soil Acidobacteria. We will then use a PCR-based screeningapproach to identify the specific conditions, or set of conditions, under whichAcidobacteria are most efficiently cultivated from soil. Our goal is to isolate and culturethose Acidobacteria which, from the results of the soil clone libraries, are found to benumerically abundant in the collected soil samples. Since our previous work suggeststhat soil Acidobacteria are strongly oligotrophic, we expect that Acidobacteria can bemost effectively cultured with nutrient-poor media and prolonged incubation times. Oncesoil Acidobacteria can be successfully isolated and cultured in vitro, their physiologicalcharacteristics can be assessed in-depth. With this project, we will significantly expandwhat we currently know about soil Acidobacteria; we will describe the genetic diversity ofthis under-surveyed taxa and, by obtaining pure culture isolates, we can begin toinvestigate the ecological roles of soil Acidobacteria. This project will provide a graduatestudent with training in both conventional microbiology (strain isolation and cultivation)and molecular microbiology (rDNA sequence analysis).