Comparative analyses of bacterial contamination and microbiome of broiler carcasses in wet market and industrial processing environments

The slaughtering environment is crucial for the food hygiene and safety of poultry products. Despite the global dominance of industrial processing, live bird slaughtering in wet markets persists due to cultural, religious, and economic reasons. This study aims to reveal the correlation between hygiene scales in wet markets and bacterial contamination levels on broiler carcasses, with a particular focus on pathobiont transmission risks and microbiome characteristics. Wet markets were categorized based on home-made ratings and the Hygiene and Biosecurity Assessment Tool (HABT). The study assessed total aerobic bacterial (TAB) levels, food spoilage and hygiene indicators (Pseudomonas and E. coli), foodborne pathogen Salmonella, and the microbiome of broiler carcasses, intestinal contents, and slaughtering facilities. Comparative analyses were conducted between market and industrial processing environments. TAB levels on broiler carcasses showed a significant negative correlation with hygiene scores, indicating that both HABT and home-made rating tools effectively assess and improve processing hygiene. Industrial processing consistently reduced bacterial contamination compared to wet markets. Although Salmonella spp. prevalence was lower in market-processed carcasses, the study identified significant cross-transmission of pathobionts and variations in bacterial composition with hygiene improvements. Notably, the microbiome analysis revealed overlaps in amplicon sequence variants (ASVs) between carcasses and contamination vectors, highlighting pathobiont transmission risks. The present study confirmed the scales of hygiene standards among wet markets reflect bacterial contamination on broiler carcasses. Enhancing slaughter practices to meet industrial hygiene standards is essential for reducing the transmission of foodborne pathogens and pathobionts, and improving food safety.