P9: Characterization of the bacterial diversity in the goat rumen and identification of enzymes with potential use in the biofuels industry

Ruminants have a powerful system for fermentation of fiber, mainly due to the presence of anaerobic microrganisms. To characterize the microbial communities present in the liquid and solid fractions of the goat rumen and identify enzymes that may have potential in the biofuels industry, a metagenomic approach was taken. Bacterial and archaeal 16S ribosomal gene libraries were constructed and clones of each library were sequenced and analyzed. The overall dominant genera in the rumen were Clostridia and Bacteroides known to play a role in plant fiber degradation in other ruminants.  Unclassified bacteria accounted for 16% of the liquid fraction sequences and 23.8% of the solid fraction sequences, indicating that a majority of the rumen microbiota is not known.  From the archaeal libraries only sequences from the phylum Euryarcheota, class Methanobacteria, were identified and a group of uncultured methanogenic Archaea not previously known to be associated with the rumen was identified. To explore the biotechnological potential of the goat rumen microbiota, a small insert metagenomic library was constructed in an expression vector and a number of functional screens for enzymatic activities were performed. Among the clones that showed different restriction digestion patterns and a stable phenotype upon retransformation were three clones with β-glycosidase activity and two clones with cellobiohydrolase activity. The characterization of these clones with potential use for the production of second generation ethanol is being pursued.