Analysis of the genome of a Pseudomonas monsensis isolate which produces the anti-fungal dipeptide maculosin

Candida albicans, responsible for approximately 647,000 deaths annually, has been identified by the WHO as a priority pathogen for targeted antifungal drug development. To this end, we have screened microbial strains from the public outreach Swab and Send project for anti-Candida activity. This process identified Pseudomonas sp. SS1954.14 which displayed potent activity against Candida albicans, both on-agar and in a cell free supernatant assay. Whole-genome analysis identified this strain as Pseudomonas monsensis. It contains several biosynthetic gene clusters suggesting it can produce hydrogen cyanide, lokisin, pyoverdine, and colicin/carocin, which may contribute to the observed antifungal activity. However, an active compound was purified by preparative high-performance liquid chromatography and identified through high-resolution mass spectrometry as maculosin (cyclo-(L-Pro-L-Tyr)). This cyclic dipeptide has previously been found to possess antifungal activity, but the exact biosynthetic mechanism remains undetermined. Reporting this genome alongside the associated evidence of maculosin production represents a valuable resource for biosynthetic investigations.