High-throughput sequencing-based characterization of human faecal                 microbiota metagenomic libraries for the selection of clones with biotechnological                 applications.
Metagenomics allow us to screen the genic content from, virtually, any                 type of environment with biological content and rendering the possibility of                 discovering products of interest. Here we propose a method to obtain                 medium-insert-size (7-15 Kb) metagenomic libraries that are sequenced through a                 hybrid approach based on pyrosequencing of clone pools and later Sanger-end                 sequencing of individual clones. Sequences are then assembled and the open reading                 frames annotated. We have applied this methodology to study human gut microbiota.                 From the 358 analysed clones from the library obtained from a faecal sample we found                 various ORFs annotated as enzymes with already reported industrial or medical                 application. Finally, forty-three ORFs were annotated as proteins of still unknown                 function. This method represents a new approach to explore microbial ecosystems,                 particularly the human gut microbiome, providing a scalable access to clones with                 potentially biotechnological and biomedical applications. Thus, previous sequence                 knowledge will drive the choice of the correct functional screening approach.