"Microbes play an essential role in the global cycling of carbon and nitrogen, but, many of the microorganisms involved in these biogeochemical cycles are, as yet, unculturable using traditional microbiological methods. Thus, essential microbial interactions and biochemical processes contributing to these cycles await discovery. Application of molecular tools can overcome limitations of non-culturability, enabling the description of microbial communities. Fishes of the genus Panaque are capable of long-term survival on a wood-only diet (xylophagy). The microbial communities in the gastrointestinal tract probably contain mechanisms for cellulose decomposition and nitrogen fixation, enabling this xylophagous lifestyle. In this study, a polyphasic approach will be employed, to overcome limitations of each technique and better describe and understand the microbes present. In this proposal traditional microbiological culture tools, microbial community profiling using 454-pyrosequencing techniques, fluorescent in situ hybridisations and functional genes analysis will be employed to provide a comprehensive view of the microbial communities present, in the different regions of the gastrointestinal tract. The major goal of this proposal is examine microbial communities associated with xylophagy and to identify novel microbial metabolic genes, enhancing our understanding of the carbon and nitrogen cycles in the environment. The study of novel microbes, enzymes and model systems can provide valuable insight into critical metabolic pathways and enable more efficient biotechnological exploitation."