Deciphering microbiome impacts on fungal-microalgal interaction in a marine environment using metabolomics

Abstract

The comprehension of microbial interactions is one of the key challenges in microbial ecology. The present study focuses on studying the chemical interaction between the toxic dinoflagellate Prorocentrum lima PL4V strain and associated fungal strains (two Penicillium sp. strains and three Aspergillus sp) among which the Aspergillus pseudoglaucus strain MMS1589 was selected for further co-culture experiment. Such rarely studied interaction (fungal-microalgal) was explored in axenic and non-axenic conditions, in a dedicated microscale marine environment (hybrid solid/liquid conditions), to delineate specialized metabolome alteration in relation to the P. lima and A. pseudoglaucus co-culture in regard to the presence of their associated bacteria. Such alteration was monitored by high-performance liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). In-depth analysis of the resulting data highlighted (1) the chemical modification associated to fungal-microalgal co-culture, and (2) the impact of associated bacteria in microalgal resilience to fungal interaction. Even if only a very low number of highlighted metabolites were fully characterised due to the poor chemical investigation of the studied species, a clear co-culture induction of the dinoflagellate toxins okadaic acid and dinophysistoxin 1 was observed. Such results highlight the importance to consider microalgal microbiome to study parameters regulating toxin production. Finally, a microscopic observation showed an unusual physical interaction between the fungal mycelium and the dinoflagellates.

Fungal Contamination in Microalgal Cultivation: Biological and Biotechnological Aspects of Fungi-Microalgae Interaction

“…This process enhances the palatability and nutritional quality of the litter for the invertebrates [ 81 ], consequently transferring energy and nutrients to higher trophic levels [ 82 ]. Nevertheless, the fungal role in the natural environment is still largely underexplored even if fungal presence has been frequently observed [ 6 , 83 , 84 ]. Different classes of fungi were identified also in artificial aquatic habitats such as: (i) urban wastewaters [ 85 ]; (ii) algal mass cultures [ 86 ]; (iii) hydroponic systems for plants [ 87 ].…”

“…Furthermore, both microalgae and fungi can be present in the same waterbody, and they are usually in competition for the nutritional resources [ 105 ]. In marine habitats, physical associations between fungi and microalgae have been reported to induce microalgal aggregation, while no data are available on their chemical interactions [ 56 , 84 ].…”