First report of detection of microcystins in farmed mediterranean mussels Mytilus galloprovincialis in Thermaikos gulf in Greece

Maria P Kalaitzidou; Christina I Nannou; Dimitra A Lambropoulou; Konstantinos V Papageorgiou; Alexandros M Theodoridis; Vangelis K Economou; Ioannis A Giantsis; Panagiotis G Angelidis; Spyridon K Kritas; Evanthia J Petridou

doi:10.1186/s40709-021-00139-4

First report of detection of microcystins in farmed mediterranean mussels Mytilus galloprovincialis in Thermaikos gulf in Greece

J Biol Res (Thessalon). 2021 Mar 10;28(1):8. doi: 10.1186/s40709-021-00139-4.

Affiliations

¹ National Reference Laboratory for Marine Biotoxins, Department of Food Microbiology, Biochemical Control, Residues, Marine Biotoxins and other water toxins, Directorate of Veterinary Center of Thessaloniki, Ministry of Rural Development and Food, Limnou 3A, 54627, Thessaloniki, Greece.
² Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece.
³ Center for Interdisciplinary Research and Innovation (CIRI-AUTH), Balkan Center, 57001, Thessaloniki, Greece.
⁴ 3rd Military Veterinary Hospital, General Staff, Hellenic Ministry of Defense, 15th km Thessaloniki-Vasilika, 57001, Thessaloniki, Greece.
⁵ Laboratory of Animal Production Economics, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, University Campus, 54124, Thessaloniki, Greece.
⁶ Laboratory of Hygiene of Foods of Animal Origin-Veterinary Public Health, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, University Campus, 54124, Thessaloniki, Greece.
⁷ Faculty of Agricultural Sciences, University of Western Macedonia, Florina, Greece.
⁸ Laboratory of Ichthyology, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, University Campus, 54124, Thessaloniki, Greece.
⁹ Laboratory of Microbiology and Infectious Diseases, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, University Campus, 54124, Thessaloniki, Greece.
¹⁰ Laboratory of Microbiology and Infectious Diseases, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, University Campus, 54124, Thessaloniki, Greece. epetri@vet.auth.gr.

Abstract

Background: Microcystins are emerging marine biotoxins, produced by potentially toxic cyanobacteria. Their presence has been reported in aquatic animals in Greek freshwater, while data are few in marine environments. Since the climate change induces eutrophication and harmful algal blooms in coastal marine ecosystems affecting the public health, further research on microcystins' presence in marine waters is required. The aim of this study was to examine the potential presence of microcystins in mussels Mytilus galloprovincialis in the largest farming areas in Thermaikos gulf, in Northern Greece, and to investigate their temporal and spatial distribution, adding to the knowledge of microcystins presence in Greek Mediterranean mussels.

Results: A 4-year microcystins' assessment was conducted from 2013 to 2016, in farmed Mediterranean mussels M. galloprovincialis, in five sampling areas in Thermaikos gulf, in northern Greece, where the 90% of the Greek mussels' farming activities is located. The isolation of potentially toxic cyanobacteria was confirmed by molecular methods. An initial screening was performed with a qualitative and quantitative direct monoclonal (DM) ELISA and results above 1 ng g^-1 were confirmed for the occurrence of the most common microcystins-RR, -LR and -YR, by Ultra High Performance Liquid Chromatography (UHPLC) coupled with a high- resolution mass spectrometer (HRMS) (Orbitrap analyzer). Microcystin-RR and microcystin-LR were detected, while the intensity of microcystin-YR was below the method detection limit. Most samples that exhibited concentrations above 1 ng g^-1 were detected during the warm seasons of the year and especially in spring. Results indicated an overestimation of the ELISA method, since concentrations ranged between 0.70 ± 0.15 ng g^-1 and 53.90 ± 3.18 ng g^-1, while the confirmation denoted that the levels of microcystins were 6 to 22 times lower.

Conclusions: Microcystin-RR and microcystin-LR were detected for the first time in mussel M. galloprovincialis, harvested from farms in Thermaikos gulf, in Central Macedonia, Greece. Their presence was linked to potentially toxic cyanobacteria. Bioaccumulation was observed in digestive gland, while the concentrations in muscles were found extremely low. Samples with levels above 1 ng g^-1 were observed mostly during spring, confirming the seasonal distribution of microcystins. The comparison of the results by the ELISA and the LC-Orbitrap MS method indicated an overestimation of concentration by the ELISA method.

Keywords: ELISA; Mass spectrometry; Microcystins; Mytilus galloprovincialis; Thermaikos gulf; cyanobacteria.