Impact of disinfection methods used in the slaughterhouse environment on microbiome diversity throughout the meat production chain

Slaughterhouse environments are prone to microbial contamination, influenced by factors like set-up, size and area as well as disinfection practices. Thus, effective control measures are crucial to prevent the spread of pathogens and their contaminant genes (antimicrobial resistance genes and virulence factors) throughout the food chain. In the present study, we assessed the microbial contamination in environmental surfaces of three slaughterhouses located in the Jaén province (Spain). We also evaluated the impact of different disinfection strategies on microbial loads and diversity by means of culture dependent and independent methods. The results revealed a statistically significant inter- and intra-specific differences in microbial loads including the most important pathogens such as pseudomonads, staphylococci, <i>Escherichia coli, Salmonella</i> sp. and <i>Campylobacter jejuni</i>. Disinfection strategies using routine disinfectant (used by the slaughterhouse), HLE disinfectant, UV, or combinations thereof showed varying effectiveness. The newly developed sustainable HLE disinfectant was most effective, while UV had the lowest disinfection strength, and routine disinfectants failed to eradicate all pathogens. Metagenomic analysis identified Pseudomonadota as the dominant phylum, followed by Actinomycetota and Bacteroidota. Results furthermore indicated shifts from sacrifice to cold rooms, with an increase in Gammaproteobacteria, particularly <i>Moraxellaceae</i> (represented by <i>Psychrobacter cryohalolentis</i>) over <i>Acinetobacter</i> sp. In conclusion, this study highlights the potential of HLE disinfectant (alone or in combination with the routine disinfectant) as a more effective disinfection measure on environmental surfaces, particularly for combating multi-drug resistant pathogens compared to other disinfection methods currently used.