Halophilic Microalgae from Trapani Salt Ponds: Bioactive Potential and Biostimulant Applications in Sustainable Agriculture

The salt ponds of Trapani, located in Western Sicily, represent unique ecosystems characterized by extreme salinity and environmental conditions, serving as a rich reservoir of extremophile biodiversity1. In this study, Dactylococcopsis salinaand Dunaliella sp. were isolated from these environments and assessed for their biological activities, including antimicrobial and plant growth-promoting (PGP) properties. For comparative purposes, Chlorella sp. was also included as a model strain. A combination of in vitro and in vivo experiments was conducted to evaluate their PGP potential. All strains were tested for salt tolerance, indole-3-acetic acid (IAA) production, and ability to solubilize phosphates. In addition, their effects on tomato seedlings (Solanum lycopersicum, cv. Regina Ostuni) were assessed through plant bioassays, which revealed significant improvements in growth parameters.