Shift in Microbial Communities in Fresh Produce Processing Environments Before and After Routine Sanitization

Multiple foodborne disease outbreaks have been reported to be associated with fresh produce caused by cross contamination during processing. However, little is known about the effect of routine sanitization on the shift in diverse microbial communities in food production environments. In this study, environmental samples were collected from 10 surface sites in a fresh-cut produce processing plant before and after the daily routine sanitization in March and June, 2017. Live bacteria population was evaluated using culture method, and quantitative real-time PCR (qPCR) after PMA treatment. The microbiota on surface samples were analyzed by 16S rDNA amplicon sequencing using MiSeq and Qiime2. Bacterial populations on surfaces from 5 sample sites (group A), including floor 1, two mezzanines, and two drain covers, significantly decreased (> 0.7 log CFU/cm2) after sanitization. Bacteria on the other 5 sample sites (group B), including floor 2, two doors, and two walls, were not efficiently removed by sanitization. Proteobacteria was the dominant phylum, and two Cupriavidus and Ralstonia spp. were determined to be the residential bacteria in the environment. In group A sample sites, the population of Pseudomonas spp., as well as other psychrophilic bacteria, were significantly reduced after sanitization. Bacteria on metal surfaces can be more efficiently removed comparing to other materials. Exogeneous bacteria, such as several Pseudomonas spp., might be introduced into the processing environment in between the two sampling events. This study provides insight on the dynamics of microbial communities in produce processing environments, which can benefit further research on the prevention of foodborne pathogens and spoilage.