Alterations in Mediterranean mussel (Mytilus galloprovincialis) composition exposed to cyanotoxins as revealed by analytical pyrolysis

Abstract

Cylindrospermopsin (CYN) and Microcystin-LR (MC-LR) are biotoxins produced by cyanobacteria species that, due to climate change and water eutrophication, proliferate together with an increase of the associated cyanotoxins. Both toxins are usually found in the aquatic environment and filter feeding organisms such as mussels are particularly exposed which may be the cause of metabolic alterations. In this work, pyrolysis gas chromatography mass spectrometry (Py-GC/MS) is used to evaluate compositional changes in mussel (M. galloprovincialis) after exposure for 14 days to cyanotoxins of Chrysosporum ovalisporum (CYN), Microcystis aeruginosa (MC-LR) and to a combination of both toxins. The pyrolysis of mussel flesh produced complex chromatograms, with up to 100 different compounds, but very similar between treatments. Major groups found were N compounds (pyridine, N-alkyl molecules) (18.2 % ± 1.5) and peptide/protein derived compounds that include alkyl indols and diketopiperazines (DKPs) (17.7 % ± 2.4), series of medium chain length (C14-C22) saturated, mono and polyunsaturated fatty acids (45.1 % ± 5.0), steroids (7.5 % ± 0.6) and aromatics with undetermined origin (8.9 % ± 1.1). A chemometric treatment of the chromatographic data allowed the discrimination between the different mussel populations exposed to cyanotoxins. The results are discussed in terms of the probable effects exerted by the biotoxins in mussel composition and the possible metabolic pathways affected.