ChipFilter: Microfluidic Based Comprehensive Sample Preparation Methodology for Metaproteomics

Metaproteomic approach is an attractive way to describe a microbiome at the functional level, allowing the identification and quantification of proteins across a broad dynamic range as well as detection of post-translational modifications. However, it remains relatively underutilized, mainly due to technical challenges that should be addressed, including the complexity in extracting proteins from heterogenous microbial communities. Here, we show that a ChipFilter microfluidic device coupled to LC-MS/MS can successfully be used for identification of microbial proteins. Using cultures of E. coli, B. subtilis and S. cerevisiae, we have shown that it is possible to directly lyse the cells and digest the proteins in the ChipFilter to allow higher number of proteins and peptides identification than standard protocols, even at low cell density. The peptides produced are overall longer after ChipFilter digestion but show no change in their degree of hydrophobicity. Analysis of a more complex mixture of 17 species from the gut microbiome showed that the ChipFilter preparation was able to identify and estimate the amount of 16 of these species. These results show that ChipFilter can be used for the proteomic study of microbiomes, in particular in the case of low volume or low cell density. ### Competing Interest Statement The authors have declared no competing interest.