Recent progress has revealed that the capture of genetic resources of complex microbial communities in metagenome libraries allows the discovery of a richness of new enzymatic diversity that had not previously been imagined. Activitybased screening of such libraries has demonstrated that this new diversity is not simply variations on known sequence themes, but rather the existence of entirely new sequence classes and novel functionalities. This new diversity, the surface of which has thus far

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... ly been scratched, constitutes potential for a wealth of new and improved applications in industry, medicine, agriculture, etc., and promises to facilitate in a significant manner our transition to a sustainable society, by contributing to the transition to renewable sources of energy, chemicals and materials, the lowering of pollutant burdens, lower processes energies, etc. Current bottlenecks in metagenomics include insufficient functional characterization and amplifying non-validated annotations of proteins in databases.