Abstract: The purpose of this study was to investigate the potential association between the bacterial community and zinc protoporphyrin (ZnPP) formation in the biceps femoris (BF) and semimembranosus (SM) muscles of Xuanwei ham of different ages (1, 2, and 3 years old) and to isolate and characterize the dominant bacteria promoting ZnPP production. Flame atomic absorption spectroscopy (FAAS), high performance liquid chromatography (HPLC) and high-throughput sequencing (HTS) were used to comprehensively analyze the color characteristics, pigment composition, metal ions and bacterial community of Xuanwei ham, with a focus on the isolation, screening and characterization of the dominant bacteria that promote the ZnPP synthesis in Xuanwei ham aged two years. The results showed that Staphylococcus was the dominant genus in Xuanwei ham, with its relative abundance showing a significant positive correlation with ZnPP content. A total of 4 Gram-positive bacteria were isolated and identified in BF and SM from two-year-old Xuanwei ham, including Staphylococcus aureus, S. epidermidis, Brachybacterium paraconglomeratum, and Tetragenococcus halophilus. In a Xuanwei ham fermentation model, inoculation with these strains resulted in higher ferrochelatase (FECH) activity and ZnPP content compared with the uninoculated control, indicating they could promote the formation of ZnPP by increasing FECH activity. The findings from this study provide a theoretical basis to understand the mechanism of the color development of meat products and for the color regulation and quality control of dry-cured ham.

Key words: zinc protoporphyrin; dry-cured ham; red pigment; Staphylococcus spp.