Retail-Level Microbiomes of Organic and Conventional Fresh Produce: A Multi-Kingdom Analysis of Amoeba-Associated Bacterial Viability.

The increasing consumption of fresh organic produce has given rise to concerns regarding the microbiological safety of minimally processed foods. Organic cultivation may be associated with increased exposure to environmental microorganisms due to soil-based inputs and reduced chemical interventions, including both beneficial taxa and potential foodborne pathogens. Fresh produce is known to harbour complex microbial ecosystems, which are shaped by farming practices, plant physiology, handling, packaging and storage, particularly in raw-consumed products such as leafy greens and strawberries. In this study, bacterial (16S rRNA) and eukaryotic (18S rRNA) communities were characterized by amplicon sequencing. In parallel, an amoeba-associated bacterial microbiome was analyzed and DVC-FISH was used to assess the viability and metabolic activity of pathogenic bacteria internalized within free-living amoebae (FLA). No significant differences in alpha or beta diversity were observed between organic and conventional products, suggesting microbiome convergence at the retail stage driven by post-harvest handling and processing. Potentially pathogenic genera, including