A Cyanobacterial outbreak in Lake Avernus: targeted and untargeted analyses and follow up actions for food safety.

Abstract

A massive Planktothrix rubescens bloom was observed during 2022 in the Lake Avernus, a volcanic lake located in Campania Region (Southern Italy). The cyanobacterial mass migrated, through a channel, to the near Gulf of Pozzuoli, causing the contamination of two marine sites dedicated to mussel farming, thus posing a potential risk for consumers' health. Mussel and water samples, from both the sea and the lake were collected weekly and analyzed by liquid chromatography coupled to tandem mass spectrometry, for identification and quantification of 10 microcystins. Moreover, the samples were analyzed by high resolution mass spectrometry in untargeted mode to determine other cyanotoxins basing on the accurate mass of the precursor ions and their MS/MS spectra. The microcystins were not detected at all, whereas other bioactive peptides, such as anabaenopeptins and oscillamide Y, were detected according to the toxicological profiles described for Planktothrix rubescens in the scientific literature. The case reported represents a modern approach for rapid characterization of some environmental outbreaks, as well as an example regarding how the public Health Authority can manage the possible risk for food safety, due to unknown substances and to enforce legal follow up actions.