REU: Microbial Ecology of Anaerobic Cellulose Decomposition

拟议研究的目的是促进对土壤和沉积物中厌氧纤维素降解的微生物生态的了解。目前，人们对在没有氧气的情况下将陆地环境中最丰富的有机物质纤维素转化为二氧化碳和甲烷的复杂微生物过程知之甚少。该项目的一个重要目标是开发方法来识别、列举和评估土壤和沉积物中厌氧纤维素分解细菌群的活性。快速RNA测序方法将用于对分离的纤维素发酵细菌菌株的16S核糖体RNA进行测序。将对序列进行比对，以识别那些由细菌群体成员共享的序列。与这些独特序列互补的寡核苷酸将被用作探针，在受控实验和环境样本中检测特定组纤维素分解细菌的存在和活性。该项目的第二个目标是使用这些探针在马萨诸塞州中部一个拟议的研究地点调查排水不良的森林土壤中纤维分解细菌的活性。最后一个目标涉及到纤维素发酵细菌固定氮气的能力。最近，来自土壤和沉积物的几种细菌菌株被证明使用纤维素作为固定氮气的能源。作为拟议项目的一部分分离的纤维素发酵细菌菌株，以及其他目前已知的菌株，将被检查是否存在固氮酶活性，以确定纤维素发酵细菌中固定氮气的能力的普遍程度，从而为在自然环境中建立碳和氮循环之间的重要联系奠定基础。这种过程很可能在许多自然系统中很常见，在那里它们可能是重要的生物过程的标志。

The goal of the proposed research is to advance understanding of the microbial ecology of anaerobic cellulose degradation in soils and sediments. At present, little is known of the complex microbial processes responsible for the conversion in the absence of oxygen, of cellulose, the most abundantly- produced organic material in terrestrial environments, to CO2 and CH4. An important objective of the project is to develop methods to identify, enumerate, and estimate the activity of groups of anaerobic cellulolytic bacteria in soils and sediments. Rapid RNA sequencing methodology will be used to sequence 16S ribosomal RNAs of isolated strains of cellulose-fermenting bacteria. Sequences will be aligned to identify those that are shared by members of groups of bacteria. Oligodeoxynucleotides complementary to these unique sequences will be used as probes to detect the presence and activity of specific groups of cellulolytic bacteria in controlled experiments and in environmental samples. A second objective of the project is to use these probes to investigate the activity of cellulolytic bacteria in poorly-drained forest soil at a proposed study site in Central Massachusetts. A final objective concerns the ability of cellulose-fermenting bacteria to fix N2. Several strains of bacteria from soils and sediments have recently been shown to use cellulose as an energy source for the fixation of N2. Strains of cellulose-fermenting bacteria isolated as part of the proposed project, as well as additional presently known strains, will be examined for the presence of nitrogenase activity in order to determine the prevalence of the ability to fix N2 among cellulose-fermenting bacteria, thus setting the groundwork for establishing an important link between carbon and nitrogen cycles in natural environments. Such processes are likely to be common in many natural systems, where they may be indications of important biological processes.