HOLOFungi

The HOLOFUNGI project explores microbial interactions in the marine environment using the toxic dinoflagellates Prorocentrum lima as a model holobiont. This micro-alga is known for toxin production (e.g. okadaic acid and dinophysistoxin-1) and contributes to Harmful Algal Blooms (HABs). This project particularly focusses on the role of fungi in the chemical mediation and toxin regulation. Four key scientific questions guide this project. (1) Which bacteria and fungi are present within the P. lima holobiont? (2) Does toxin production in P. lima is always increase by fungal interaction? (3) Does P. lima-derived carbon sources is used for growth by the Heterotrophic fungi? (4) Does P. lima and associated fungi produce chemical signals able to shape the holobiont microbial community? Preliminarily, we show that a fungus (Aspergillus pseudoglaucus) was able to induce toxin production in P. lima, suggesting chemical mediation. This was further confirmed for compounds isolated from associated fungi with such activity. The HOLOFUNGI project aims to provide a comprehensive understanding of these interactions. First, the bacterial and fungal communities within the P. lima holobiont will be described using metabarcoding and a culture-dependent approaches (WP1). Then the chemical interaction within the holobiont will be delineating (WP2) by exploring nutrient exchange through isotope labelling and toxin induction in P. lima through metabolomics strategy. (WP3) In addition, complete chemical signal related to chemical mediation will be described from P. lima and its originating fungi. This will be achieved through purification and characterisation, prior to their evaluation as signals involved in P. lima toxin regulation and microbiome interaction (antimicrobial compounds). The HOLOFUNGI project advances understanding of fungi's role in marine environments and their impact on toxin regulation in toxic dinoflagellates like P. lima, contributing to marine holobiont understanding.