A bacterial ecology study to improve shelf life of food products: meat microflora in swine fed with polyphenols from olive mill waste

Meat is an excellent substrate for bacterial growth and different factors (e.g. pH, redox potential, processing conditions) influence its microbial communities. Animal feeding strategy is the management factor most actively used as a quality control tool in meat production and the use of dietary antioxidants is recommended to preserve product quality. Olive mill wastes are sources of phenolic compounds with antioxidant and antimicrobial properties and a development of new bioremediation strategies is currently needed to overcome ecological problem. This study is an evaluation of the employment of polyphenols obtained from olive mill wastes in the swine productive chain to identify possible correlation among feedstuff enrichment and meat microbial quality. To obtain a comprehensive view of the meat microbial biodiversity a 16S rRNA pyrosequencing approach was used. RNA was extracted from nine meat samples conserved at 4°C, collected at 12 days from slaughter and derived from three groups of diets (control, phenolic extract and phenolic extract plus PUFA feedstuff enrichment). cDNA was amplified with primers targeting the V3-V4 region of 16S rRNA gene and analyzed using the 454/Roche GS Junior technology. Subsequent analysis were carried out using the QIIME (Quantitative Insights Into Microbial Ecology) pipeline. Dietary enrichment resulted in a increased microbial α-diversity and richness. The enriched diets significantly decreased the relative abundances of Pseudomonas and Brochothrix genera. In particular, Pseudomonas spp. constituted 83.9% of OTUs in control samples and 38,6% in meat derived from animals fed with phenolic extract plus PUFA. These interesting effects are accompanied by a increased abundance of the Lactobacillales order in the treated samples. Phenolic extract clearly influences the composition of the swine meat microflora and seems to ameliorate flesh quality and shelf-life.