MALDI Mass Spectrometry Imaging for Microbiology
Microorganisms have the biosynthetic capacity to produce an armamentarium of small molecules, often referred to as natural products. These small molecules have been historically exploited for their therapeutic potential by employing bioassay-guided fractionation, which has led to the discovery and use of penicillin, doxorubicin, and ivermectin among others. While microorganisms are typically grown on solid agar or agarose, their sample preparation for MSI has seen a variety of creative adaptations in the last decade, mainly pertaining to changes in their media nutrient requirements and the downstream effects these different additives have on sample preparation. With these adaptations, MSI has evolved as a powerful technique for drug discovery in antagonistic interactions, imaging microbial metabolites in hosts or host tissues, and chemical ecology applications in mapping microbial crosstalk across different domains of life. This chapter will discuss sample preparation for agar-based imaging protocols, as well as applications in microbial chemical ecology, drug discovery, and host–microbe interactions. We will also offer a short prospective on future MSI applications for microbiology.