Metabolic Differences in Microbial Cell Populations Revealed by Nanopnotonic Ionization

摘要

Growing interest in functional genomics has resulted in technological breakthroughs in advanced proteomics, including the intracellular microproteomic analysis of tissues and cells. Quantitative differences in the proteome at the single-cell level can be detected by flow cytometry and fluorescence, as well as mass spectrometry, whereas microbial single cell metabolomics has not progressed as rapidly because it involves studying compounds of larger chemical variety, higher turnover rates, and lower molecular weights, coincident with the mass range of common contaminants. Owing to the low copy number of some intracellular proteins and the presence of extracellular noise, isogenic cells can exhibit large differences in their metabolic makeup. This metabolic noise, part of cellular differences, is poorly characterized because it requires the multicomponent analysis of severely volume-limited samples, that is, individual microbial cells. A technique that can capture metabolic variations for a large fraction of the hundreds to thousands of metabolites in single cells or small populations requires a combination of ultra-low limits of detection, high selectivity, and high quantitation capability.