MALDI-FISH for Colocalization of Brominated Metabolites and <i>Pseudovibrio</i> spp. in <i>Aplysina</i> Tissue

Bromotyrosine-containing natural products have been isolated from marine sponges. While studying the uptake of engineered bacterial strains by sponges, we observed the production of fistularin-3 in the sponge. To explore these results, we employed multimodal imaging to colocalize metabolites with fluorescent in situ hybridization (FISH) probes. Using mass spectrometry imaging (MSI), we measured fistularin-3 and mapped this against the FISH probes to locate the bacteria. A recent study reported that <i>P. brasiliensis</i> produced fistularin-3 in pure culture, but these data have not yet been reproduced. We employed MSI and FISH to colocalize the fistularin-3 spatial distribution with <i>P. brasiliensis</i> in sponge tissue.