Fig. 1

Functional metaproteomics as a tool to discover biocatalysts. a Schematic representation of the functional metaproteomics workflow. Metagenomics and functional metaproteomics combine the immediacy of an activity-based approach, while still retaining the comprehensive information of the metagenome. Optimization of DNA and protein extraction protocols can be found in Additional file 1: Figure S2 b 2D gel electrophoresis of the enriched sample stained with RuBPS Protein Gel Stain. LS-001 was excised as landmark spot. c In-gel activity assay for identifying lipolytic enzymes in the metaproteomic sample. Methylumbelliferyl-butyrate was hydrolyzed by lipolytic enzymes present in the gel. Resulting methylumbelliferone was detected under ultraviolet light. Fourteen spots (ML-001–ML-014) were manually excised for subsequent mass spectrometric analysis. Representative results shown, results of both technical replicates can be found in Additional file 1: Figure S3