Co-exposure to Polyethylene Fiber andSalmonella entericaTyphimurium Alters Microbiome and Metabolome ofin vitroChicken Cecal Mesocosms

Abstract

Humans and animals encounter a summation of exposures during their lifetime (the exposome). In recent years, the scope of the exposome has begun to include microplastics. Microplastics (MPs) have increasingly been found in locations where there could be an interaction withSalmonella entericaTyphimurium, one of the commonly isolated serovars from processed chicken. In this study, the microbiota response to a 24-hour co-exposure toSalmonella entericaTyphimurium and/or low-density polyethylene (PE) microplastics in anin vitrobroiler cecal model was determined using 16S rRNA amplicon sequencing (Illumina) and untargeted metabolomics. Community sequencing results indicated that PE fiber with and withoutS.Typhimurium yielded a lowerFirmicutes/Bacteroidesratio compared to other treatment groups, which is associated with poor gut health, and overall had greater changes to the cecal microbial community composition. However, changes in the total metabolome were primarily driven by the presence ofS.Typhimurium. Additionally, the co-exposure to PE Fiber andS. Typhimurium caused greater cecal microbial community and metabolome changes than either exposure alone. Our results indicate that polymer shape is an important factor in effects resulting from exposure. It also demonstrates that microplastic-pathogen interactions cause metabolic alterations to the chicken cecal microbiome in anin vitrochicken cecal model.IMPORTANCEResearching the exposome, a summation of exposure of one’s lifespan, will aid in determining the environmental factors that contribute to disease states. There is an emerging concern that microplastic-pathogen interactions in the gastrointestinal tract of broiler chickens may lead to an increase inSalmonellainfection across flocks and eventually increased incidence of human salmonellosis cases. In this research article, we elucidated the effects of co-exposure to polyethylene microplastics andSalmonella entericaserovar Typhimurium on the ceca microbial community.Salmonellapresence caused strong shifts in the cecal metabolome but not the microbiome. The inverse was true for polyethylene fiber. Polyethylene powder had almost no effect. The co-exposure had worse effects than either alone. This demonstrates that exposure effects to the gut microbial community are contaminant specific. When combined, the interactions between exposures exacerbate changes to the gut environment. The results herein support currentSalmonellamitigation efforts and understanding microplastics-pathogen interactions.