Search

Plastics (macro, micro and nanoplastics) are durable and persistent pollutants that may alter pelagic and coastal ecosystem functions. Plastics provide a durable substrate that can be colonized by micro and macro-organisms. They support the growth of potential pathogens and HAB species. Further, plastic debris has been considered to play a key role in the dispersal also of biotoxins. The present study aimed to investigate harmful phytoplankton assemblages that colonized numerous samples of micro and macro-plastics collected in the Mediterranean Sea by qPCR assays, and to forecast toxin dispersal by quantifying toxin content onto plastic debris. Further, the impact of polystyrene nanoparticles (PS NPs) to the HA diatom Skeletonema marinoi was analyzed. All plastic samples were positive for the presence of Dinophyceae and Bacillariophyceae communities and some plastic samples were colonized by toxic species of dinoflagellate Alexandrium pacificum, Alexandrium minutum, Ostreopsis cf. ovata and diatom Pseudo-nitzschia spp. Strains of A. pacificum isolated from plastic debris and analyzed by LCHRMS produced PST (paralytic shellfish toxins). The levels of potential toxins on plastic samples ranged from 101 to 102 ng cm-2. The interactions between HA diatom and plastic nanoparticles demonstrated an increase of both extracellular and intracellular reactive oxygen species, and significantly reduced colonies length using TEM and SEM techniques. Then, plastics can negatively impact the ecological functioning of oceans. The potential risk of harmful microalgae dispersal associated with plastic pollution was illustrated as well as for chemical compounds to transfer through the trophic chain with implications for human health and marine ecosystem.

Harmful Algal Blooms (HABs) are massive proliferations of toxic algal species that occur under appropriate climatic and environmental conditions. HABs may exert their adverse impacts on both the environment and living organisms through the production of marine biotoxins. Consumption of contaminated seafood or also direct exposure to marine biotoxins (swimming, aerosols etc.) can result in human illness or even death. Thousands of marine toxin-related human intoxications are reported every year on a global basis. In Italy, research on marine biotoxins has shown a continuously changing toxin profile with most of the toxin classes so far known being present in seafood and seawater. Starting from the late ‘80s with the first finding of a marine biotoxins, okadaic acid, along the Italian coastline, a number of other classes of marine toxins have been found, namely yessotoxins, pectenotoxins, saxitoxins, domoic acid, spirolides, palytoxins, and azaspiracids. Herein, in chronological order, we provide an overview of the many classes of marine biotoxins that have infested the Italian seawater over the past 25 years.

Ostreopsis spp. once confined to tropical and subtropical areas have recently spread to temperate regions such as the Mediterranean and the Southern-Atlantic coasts of Europe with relevant negative impact on human health through skin contact and inhalation of toxic aerosols. Following Ostreopsis-related outbreaks, we developed a liquid chromatography-high resolution mass spectrometry (LC-HRMS) method for the analysis of algal samples. Our studies characterized O. cf. ovata as producer of palytoxin congeners, including a putative palytoxin and ovatoxins. Toxin profiles of different algal strains appear sometimes different both qualitatively and quantitatively and the presence of further new ovatoxins is emerging. Herein we report on a systematic study of over 40 Mediterranean strains of O. cf. ovata. All of them showed to produce ovatoxins although at different levels. Four types of toxin profiles were identified. Most of the strains produced ovatoxin-a as major component of the toxin profile while a significant number of strains did not produce ovatoxin-b and -c. Unique toxin profiles were found in a strain from the Adriatic coast of Italy, in which ovatoxin-f was the dominant toxin, and in a strain from the French Mediterranean coast, which produced only ovatoxin-b and c. On a per cell basis, toxin contents were in the range 5-230 pg/cell. In light of the structural complexity of ovatoxins, a LC-HRMSn based approach was employed to gain structural insights on known and unknown components of toxin profiles that could be available in too small amounts to be studied by NMR.

The harmful blooms of the benthic dinoflagellate Ostreopsis cf. ovata are a concern in the coastlines of the Mediterranean Sea, since it produces a wide range of palytoxin-like compounds listed among the most potent marine toxins. This study focused on two analogs of palytoxin found in cultures of two Ostreopsis cf. ovata strains isolated from the south of Catalonia (NW Mediterranean Sea) in August, 2011. Our strains produced two novel compounds, ovatoxin-g and an isomer of palytoxin whose structures had not been elucidated yet. Although the quantity of these compounds was not sufficient for a full NMR-based structural elucidation, thus we studied their structure through Liquid Chromatography Electro Spray Ionization High Resolution Mass Spectrometry (LC-ESI-HRMS) in positive ion mode, following the LC-HRMSn approach developed by Ciminiello et al. Under the used MS conditions, the molecules underwent fragmentation at many sites of their backbone and a large number of diagnostic fragment ions were identified. Their MSn spectra were investigated in light of the reported structure of ovatoxin-a and palytoxin from Palythoa tuberculosa (commercially available as analytical standard). As a result, ovatoxin-g was tentatively identified as 46-deoxy-ovatoxin-a, while the novel isomer of palytoxin would have two additional hydroxyl groups (one in the region C1 and C8 and one at C42) and two hydroxyl lacking (one at C17 and one in the region C53 and C79, compared to palytoxin standard. Ovatoxin-g and putative palytoxin were the least abundant palytoxin-like compounds (0.8% and 0.4% respectively) in a toxin profile dominated by ovatoxin-a (53%). Ovatoxin-b to –e (30%, 4%, 6%, 7% respectively) were also present, while production of ovatoxin-f was not observed. These strains are still under investigation to confirm the presence of other potentially new palytoxin congeners.