CHEMICROS · CHEmically-mediated MICRobial Interactions maintained by the toxic dinoflagellate OStreopsis cf. ovata

CHEmically-mediated MICRobial Interactions maintained by the toxic dinoflagellate OStreopsis cf. ovata

Proliferation of harmful marine microalgae are increasing worlwide due to eutrophication and temperature rise of surface waters. These Harmful Algal Blooms (HABs) cause damages to living organisms through high biomass accumulation or through production of biotoxins in the algal cells. Extensive repercussions of HABs on human health, aquatic species, commercial fisheries, aquaculture and tourism are yearly recorded worldwide and related economic losses can be measured in millions of dollars. Given their impacts, the increasing occurrence of HABs worldwide constitutes a major ecological issue for the coming decades. HABs species are highly suspected to rely on chemical interactions with the microbial community to support their proliferation. A better understanding of these interactions could help improving management strategies for HABs events, including mitigation and forecasting. In this context, the project CHEMICROS aimed to investigate the microbial control on the toxicity of blooms of the benthic dinoflagellate Ostreopsis cf. ovata. This species is now well settled in the Mediterranean Sea and frequently leads to respiratory distress or dermatitis in Humans. Three main scientific objectives were investigated: (1) influence of the chemical interactions between the bacteria and Ostreopsis on the algal growth and the phycotoxins’ biosynthesis, (2) evaluation of the transformation of waterborne phycotoxins exposed to bacteria and solar radiation, as well as the assessment of the transfer of the phycotoxins to the sea spray aerosols, and (3) characterization of an algicide produced by a co-occurring benthic diatom as a promising bio-agent for bloom mitigation. To meet the stated objectives, a combination of laboratory work with cultures of microalgae and field campaigns was used. State-of-the-art analytical tools such as High Resolution Mass Spectrometry (HRMS) allowed the measurement of low-levels of phycotoxins in complex matrices. Un-targeted metabolomics approaches and molecular networking allowed the identification of phycotoxins by-products or chemical mediators of the bacteria-microalgae interaction. Approaches in natural products chemistry were used to isolate and characterize the algicidal compound. This action allowed gaining more fundamental knowledge on the chemical interactions maintained by Ostreopsis and its bacterial community, as well as the control by bacteria on the phycotoxins’ biosynthesis. Also, the insights gained on the instability of the phycotoxins produced by O. cf. ovata and the mechanisms driving their transfer to the sea spray aerosols are of significant importance to unravel the toxic effects on human health associated with these blooms. Lastly, the identification of a bio-agent that inhibits temporarily the cell’s proliferation may pave the way for innovative solutions for the bio-mitigation of these toxic blooms.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз