MALDI-TIMS-MS Imaging and Annotation of Natural Products in Fungal-Bacterial Coculture.

Mass spectrometry imaging (MSI) is a powerful tool for monitoring the spatial distributions of microbial metabolites directly from culture. MSI can identify secretion and retention patterns for microbial metabolites, allowing for the assessment of chemical communication within complex microbial communities. Microbial imaging via matrix-assisted laser desorption/ionization (MALDI) MSI remains challenging due to high sample complexity and heterogeneity associated with the required sample preparation, making annotation of molecules by MS alone challenging. The implementation of trapped ion mobility spectrometry (TIMS) has increased the dimensionality of MALDI-MSI experiments, allowing for the resolution of isomers and isobars, and can increase sensitivity of metabolite detection within complex samples. Parallel reaction monitoring-parallel accumulation serial fragmentation (prm-PASEF) leverages TIMS to enhance the targeted acquisition of MS data by increasing the number of precursors that can be fragmented in a single acquisition. Recently, imaging prm-PASEF (iprm-PASEF) has been developed to provide more accurate annotation from MALDI-TIMS-MSI data sets through the inclusion of MS. Here, we showcase the use of MALDI iprm-PASEF to provide rapid and accurate annotation of coproporphyrin III directly from a bacterial-fungal coculture between (strain JB182) and (strain #12). Additionally, we present a workflow for untargeted iprm-PASEF precursor selection directly in SCiLS Lab, followed by direct export for iprm-PASEF acquisition.