Raman microspectroscopy imaging analysis of extracellular vesicles (EVs) biogenesis by filamentous fungus Penicilium chrysogenum

Mechanism of production of extracellular vesicles (EVs) and their molecular contents are of great interest owing to their diverse roles in biological systems and are far from being completely understood. Even though, cellular cargo release mediated by EVs have been demonstrated in several cases, their role in secondary metabolite production and release remains elusive. In this study we investigate this aspect in detail using Raman micro-spectroscopic imaging. We provide considerable evidence to suggest that the release of antibiotic penicillin by filamentous fungus Penicillium chrysogenum involves EVs. Morphological modifications of the fungal body during biogenesis, changes in cell composition at the locus of biogenesis, and major molecular contents of the released EVs are also revealed in this study. ImportanceExtracellular vesicles (EVs) play a key role in cellular communications. EVs role in functioning of fungi are relatively less explored. Here we show selective enrichment of chemical contents at certain locations of mycelium of P. chrysogenum forming protruding regions. Secondary metabolite penicillin is excessively localized in them. We provide evidence to show that EVs are released from these protrusions. Raman imaging has been applied for molecular profiling of the mycelium and for characterizing chemical contents of the EVs. Our study suggests a possible general role of EVs in the release of antibiotics from the producing organisms.