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.
