This project was conceived to tackle the inherent hurdles in unveiling – and using – the metabolic capacities of typically “unculturable” symbiotic microorganisms believed to play key roles in ecosystem functioning and to be promising sources of novel biotechnological appliances. The focus on the marine sponge microbiome allows us to interrogate keystone enzymatic activities of industrial interest using a chemically fertile biological source of widespread occurrence across the planet´s ocean. To this end, the project has the following specific objectives: 1) To profile the functional microbial diversity present in the marine sponge metagenome vs. the metamobilome; 2) To mine for novel chitinase, dehalogenase, and polyketide-synthase encoding genes – and activities – from the metagenomes and metamobilomes of marine sponge symbiotic consortia; 3) To identify and sequence the genomes of thus far “uncultivatable”, novel bacterial species found to display the abovementioned features using innovative symbiont cultivation methods; 4) To improve the performance of naturally-occurring enzymes from uncultivated microorganisms in the laboratory.