A Survey of Microbial Communities on Dry-Aged Beef in Commercial Meat Processing Facilities

Many artisanal meat professionals believe that the microbial populations on the outer crust of dry-aged beef contribute to variation in sensory profiles; however, to date there is minimal information about the microbes themselves that grow on commercially produced dry-aged beef. The microbiome of dry-aged beef bone-in strip loins (Institutional Meat Purchase Specifications #175) from 5 commercial dry aging facilities, including one utilizing ultraviolet light treatment, were surveyed to assess the microbial populations residing on and within each subprimal. Each strip loin was sampled at multiple spatial locations and depths, and the microbial sequences present in the samples were identified using a nextgeneration sequencing approach. Insufficient microbial DNA was isolated from ultraviolet-light-treated strip loins, indicating that this treatment eliminates all or most microbial growth on the meat. Sequencing results indicated that each establishment was producing meat with different microbial communities, based on Permutational Multivariate Analysis of Variance (P < 0.01) and clustering in the Principal Coordinates Analysis plot of Jaccard distances. The position on strip loins from which samples were taken had negligible influence on microbial community structure. Aging facility, and the relative unique environmental conditions within, was determined to be the only observed driver of community structure. Notable operational taxonomic units (OTUs) detected included the spoilage-associated bacterium Pseudomonas fragi and the fungal species Debaryomyces udenii and Penicillium polonicum. An OTU identified as Mucor sp. PG272 was found to be present in over 75% of all samples. This OTU may represent a species similar to Thamnidium, a mold that has been associated with product quality. This study established a general core microbiome for dry-aged beef observed in commercial facilities, variations of which may—as future research could indicate—contribute to distinct sensory properties.