Phenotyping of gut microbiota: Focus on capillary electrophoresis

The analysis of the microbial metabolome is crucial to fully understand the symbiotic relation between humans and microbes. That is why an explosion of metabolomics took place in the area. So far, at least several hundreds of microbial metabolites have been shown to be statistically altered when humans undergo a plethora of commonly faced perturbations. NMR and MS, usually coupled with GC, LC and CE have revealed their identities. CE is a robust analytical platform for the analysis of polar and ionic metabolites that are essential in order to assess the cells' activity. Due to its novelty, only 5% of the metabolomics studies investigate gut microbiota using CE, even though the metabolites found by CE as being significantly altered in human microbiota represent around 23% of the total number of metabolites identified by metabolomics tools. Herein, we discuss the advances of metabolomics in the frame of other OMICS techniques for human gut microbiota analysis. Afterwards, we focus on sample treatment, analytical methods and data processing in CE coupled to any detector that have been reported to date in order to enhance metabolite coverage in the art, and to identify metabolite markers that cannot be covered by other platforms but are of key importance for determining microbial activity and human health.