This project focuses on a fascinating group of fish - armored catfish, from the genus Panaque, which include members that are capable of surviving and obtaining energy by eating wood. Wood eating, or xylophagy, is a rare dietary strategy and often involves a complex intestinal tract microbial community. A major goal of this project is to identify the microbial communities present in the gastrointestinal (GI) tract of the wood eating Panaque nigrolineatus and examine the mechanisms used for cellulose decomposition and nitrogen fixation that enable this xylophagous lifestyle. A long-term dietary experiment will be performed to compare the microbial communities in fish fed an herbaceous diet to those fed a wood-only diet. DNA sequencing and other molecular methods will allow the description of microbial communities in fish subjected to different dietary regimes and furthermore, compare microbial communities in different regions of the fish GI tract, pinpointing key areas involved in cellulose breakdown. Nitrogen fixation will also be examined by isolating genes involved in this vital global process, and by culturing nitrogen fixing microorganisms associated with the Panaque GI tract. Broader scientific implications of this project include enhancing our knowledge of cellulolytic and nitrogen fixation gene diversity and the importance of the microbial community within xylophagous fish. Cellulose is the most abundant carbon polymer in the biosphere, yet, few degradation pathways have been characterized. As cellulose is an important compound in the global carbon cycle and a potential source for biomass fuel generation, gaining a better better understanding of its degradation in the environment is critical. Furthermore, discovery of novel pathways may have critical implications for biofuel production and the global carbon and nitrogen cycles. Educational impacts include the training of graduate and undergraduate students during this research project. An outreach activity with a Baltimore City elementary school is planned, enabling a hands-on opportunity for children in grades 3-8 with the goal of promoting science as a career choice for these children.
