Antibiotic resistance in various microbes is a growing problem. Throughout the last century, many antibiotics have been discovered and used for the treatment of infectious diseases. Unfortunately, the increased use of antibiotics leads to the microbes responsible for these infections developing drug resistance. In this context, finding novel antibiotics has become a research area of significant interest. Many microbes produce their own antibiotics. Janthinobacterium lividum bacteria is known to display antifungal activity, specifically inhibiting the growth of the Batrachochytrium dendrobatidis (Bd) fungus. This fungus is threatening global amphibian populations with an epidemic of the disease chytridiomycosis. Cutaneous amphibian bacteria such as J. lividum can aid in defense against fungal infections by producing compounds with antifungal properties. 

In collaboration with UMass Boston’s CURE Microbiome course, we set out to test the effect of J. lividum bacteria cultured from frog skin on the Bd fungus. Our research focuses on isolating the organic compounds produced by two strains of J. lividum bacteria, J. lividum VT36D and J. lividum CO. We collected a similar purple crude extract from both of our strains, and using paper disk assays with Bd fungus, we observed significant growth inhibition. Using liquid-liquid extraction, high-performance liquid chromatography (HPLC), H-NMR, and mass spectroscopy, we isolated and identified the key antimicrobial compounds in these strains of bacteria. We detected deoxyviolacein from J. lividum VT36D, a visibly purple compound with antifungal properties. We also detected violacein from J. lividum CO, another purple antifungal compound with a similar molecular structure. During the isolation process, we used thin-layer chromatography (TLC) and found that Methanol-D4 was an effective solvent to dissolve these specific compounds. Finally, we used a new solvent, DMSO, to investigate the effects of the solvent on our structural analysis of these antimicrobial compounds, and we were able to further support the identity of violacein.