Recent advances in imaging desorption electrospray ionization-ion mobility-mass spectrometry (DESI-IM-MS) afford the ability to rapidly and deeply characterize bacteria at ambient pressure with minimal sample preparation. We have developed strategies based on these advances to characterize the spatial distribution of expressed molecules from bacterial colonies that are co-cultured in close contact to visualize the distribution of expressed molecules. In essence, this provides a snapshot of the complex chemical communication that is occurring between the two species. This methodology has provided a well-suited means for characterizing new and unique molecules that can be targeted for drug discovery efforts in natural products research. We have expanded these advances for rapid phenotyping in synthetic biological workflows. While developments in synthetic biology have allowed for the rapid production of genetic variants, this has outpaced the phenotypic screening capabilities of traditional analytical workflows. The acceleration of strain phenotyping is a critical need for effective determination of optimal target sequences for genetic engineering. The imaging DESI-IM-MS platform for this purpose that enables broadscale molecular phenotyping, including the analysis of labile and volatile small-molecules. Through untargeted acquisitions and unsupervised segmentation, this multiplexed method is able to efficiently determine the metabolic phenotypes of genetically modified bacterial colonies. This strategy is demonstrated through the analysis of Escherichia coli strains engineered to overproduce free fatty acids (FFAs), wherein a single acquisition is able to distinguish individual phenotypes present within a co-culture and identify strains with the highest FFA production. Because of the technique’s untargeted approach, global metabolic information related to off-target production, product sinks, and membrane lipid compositions is also gained. This report describes the recent advances and remaining challenges in imaging DESI-IM-MS strategies for rapid and comprehensive phenotypic molecular characterization of bacteria.

Accelerating phenotyping in drug discovery and synthetic biology with imaging ion mobility-mass spectrometry

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.