Highlighting the Underestimated Role of Fungi in Food Safety and Occupational Health: Preliminary Screening of Potential Mycotoxigenic Fungi Isolated from Slaughterhouses and Cutting Rooms in Northern Portugal

Background: Mycotoxins are fungal secondary metabolites with carcinogenic and genotoxic potential, and contamination can occur throughout meat processing facilities. Assessing the presence of mycotoxin-producing fungi is essential for food safety and occupational health within a One Health framework. Coconut Agar Medium (CAM) allows screening of fungal isolates for mycotoxin production, specifically aflatoxin and citrinin, detectable as fluorescence under UV light. This study performed a preliminary screening of fungi isolated from slaughterhouses and cutting rooms in northern Portugal.

Methods: Between July and December 2025, air, surface, and carcass samples were collected from slaughterhouses and cutting rooms for ruminants and pigs in northern Portugal. Air samples were collected passively using Chloramphenicol Glucose Agar (CGA) Petri dishes, while carcass and surface samples were obtained with sterile pre-moistened sponges. Fungal isolates were screened for mycotoxigenic potential on Coconut Agar Medium (CAM) using UV fluorescence (365 nm). Pure cultures were subcultured in the last week of February, excluding yeast-containing plates, and some sampling locations yielded more than one plate if multiple fungal species were isolated.

Results: Of the 48 analysed plates, 20 originated from fungal cultures isolated from slaughterhouse air, 13 from air and surface samples in cutting rooms, 9 from carcass swabs, and 6 from lairage air samples. Seventeen plates were strongly fluorescent (35.4%), 19 were slightly fluorescent (39.6%), and 12 showed no fluorescence (25.0%). Strong fluorescence was observed in cultures from slaughterhouse air before and during slaughter (n = 7), lairage air (n = 2), cutting room air and surfaces (n = 4), and carcass swabs before and after meat inspection (n = 4). Sequencing of isolates from fluorescent and slightly fluorescent plates revealed a diverse range of fungal species, including A. fumigatus, P. brevicompactum, P. crustosum, P. canescens, and P. solitum.

Conclusions: Fungal isolates with potential mycotoxigenic activity were detected in slaughterhouse air, lairage areas, cutting rooms, and on carcass surfaces. Fungal isolates with potential mycotoxigenic activity were detected in slaughterhouse air, lairage areas, cutting rooms, and on carcass surfaces. These findings are preliminary, and further analytical characterisation is required to confirm and identify the specific metabolites involved.