Insights into Microbial Community and Its Enzymatic Profiles in Commercial Dry-Aged Beef

Dry-aged beef has gained interest worldwide in recent years due to its improved sensory attributes. This enhancement is thought to be partially driven by microbial activities, particularly lipolysis and proteolysis. In this study, dry-aged beef manufactured by seven commercial producers in China was analyzed. The pH value and total volatile base nitrogen value of dry-aged beef were determined. High-throughput amplicon sequencing of full-length 16S rRNA genes and internal transcribed spacer (ITS) regions was used to analyze the microbial community. A total of 207 proteolytic and lipolytic isolates were identified by sequencing 16S rRNA genes for bacteria and sequencing the D1/D2 region of 28S rRNA genes and the ITS region for fungi. The results revealed that the crust harbored greater numbers of bacteria and fungi than the interior. The bacterial community was dominated by <i>Pseudomonas</i> species, which were core members in both the crust and interior, while <i>Brochothrix thermosphacta</i> was identified as a core bacterium exclusively in the crust. The fungal community primarily constituted <i>Candida sake</i>, <i>Kurtzmaniella</i> species, and members of the phylum Chytridiomycota. Proteolytic and lipolytic isolates were mainly identified as <i>Pseudomonas</i> sp., <i>B. thermosphacta</i>, <i>Carnobacterium maltaromaticum</i>, <i>Candida zeylanoides</i> (teleomorph: <i>Kurtzmaniella zeylanoides</i>), <i>C. sake</i>, and <i>Debaryomyces hansenii</i>. Two strains of <i>C. zeylanoides</i> and <i>C. sake</i> exhibiting high proteolytic and lipolytic activities effectively hydrolyzed beef fat, myofibrillar protein, and sarcoplasmic protein. This study characterized the main microorganisms and their enzymatic functions associated with dry-aged beef, highlighting the need to explore their contributions to the sensory attributes of dry-aged beef.