Similar carcass surface microbiota observed after slaughter of different pig batches

Bacterial contamination during slaughtering process is a safety problem and concern for shelf life in pork meat production. The gut microbiota is one of the most important source of contamination for carcass surface. The intestinal microbiota varies between swine from different farms and this could be reflected on the bacterial contamination of the carcass. In this study, we compared the surface microbiota of 26 carcasses, coming from by six different farms (batches) and slaughtered on the same day to observe if the carcass surface microbiota also vary between different batches. The microbiota of the upper and lower surface area was analyzed by culture of classical indicator microorganisms (mesophilic aerobic flora, Enterobacteriaceae, Escherichia coli, Pseudomonas and lactic flora), by Salmonella detection and by 16S rRNA gene sequencing. Comparing culture showed that the lower part of the carcass (shoulder) was more contaminated by spoilage bacteria like Enterobacteriaceae, E. coli and lactic flora when compared to the upper parts. Salmonella was not detected in any swab samples. Microbiota analysis validated a difference between the upper and lower carcass microbiota. Despite presence of some genera associated with faecal contamination such as Terrisporobacter, Escherichia-Shigella, Turicibacter, Clostridium sensustricto1 and Streptococcus in carcass surface, microbiota analysis suggested that there was no difference between the different batches of pork for the upper or lower carcass samples. Slaughter process therefore appears to participate to the uniformization of the carcass surface microbiota with some specific bacteria present depending on the carcass area sampled.