Cross-Cutting Approach for the Characterization of Microbial Emerging Hazards in Agriculture Settings from Circular Economy-Driven Wastewater Streams

Abstract

The recycling of biowaste from municipal wastewater treatment plants (WWTPs) in agriculture represents a circular economy-driven source of water and nutrients to support food system sustainability. However, biowaste may represent the source of emerging hazards of anthropogenic and animal origin that can transfer from agricultural soils to related food production, posing a risk to consumers' health, as in the case of outbreaks due to the consumption of ready-to-eat leafy vegetables contaminated with pathogenic E. coli. From this perspective, we propose a combined strategy based on both classical methods and culture-independent metagenomics approaches to identify microbial hazards relevant to foodborne diseases in WWTP-related biowastes. The virulence genes targeted by real-time PCR, performed before and after the enrichment of the raw samples, may represent a proxy for the viability of pathogens, the presence of which is then confirmed via classical microbiological methods. Bioinformatics analysis of shotgun metagenomic sequences could assess the presence of genes associated with resistance to specific antimicrobials followed by phenotypic confirmation via cultivation of the raw samples in the presence of the predicted molecules. Bacterial 16S rDNA analysis supports biowaste traceability based on their taxonomic composition. This strategy would support a "One Health" Action based on a cross-cutting assessment of emerging food-borne risks along the food chain.