Antifungal activity and mycotoxin-inhibiting potential of amphisin and rhamnolipids from Pseudomonas strains

Biosurfactants, due to their amphiphilic properties, are widely used across a broad spectrum of industries. In this paper, we describe experiments conducted to determine the antagonistic activity of amphisin and rhamnolipids against fungal plant pathogens. The bacterial strains used for biosurfactants production were Pseudomonas fluorescens DSS73 and Pseudomonas aeruginosa #112. Both amphisin and rhamnolipids were produced using waste raw materials from the food industry. The biosurfactants exhibited significant antifungal activity and the ability to reduce sterigmatocystin production. The most significant inhibition was observed during the initial days of the experiments, followed by a gradual decrease in biosurfactants activity. However, a long-term effect was obtained against Aspergillus amoenus DSM 1943, Penicillium nordicum DSM 12639, and Monilinia fructigena IOR 2138. Additionally, sterigmatocystin production in cultures of A. amoenus DSM 1943 and Aspergillus quadrilineatus DSM 820 was reduced by 89–99%, with the most significant results observed for rhamnolipids. Therefore, as demonstrated in this research, Pseudomonas-derived biosurfactants show great potential in plant cultivation by protecting against fungal invasion. Amphisin and rhamnolipids can be successfully applied as eco-friendly solutions to limit sterigmatocystin accumulation during crop storage.