Modulating spoilage microbiota and antimicrobial susceptibility in brown bear (Ursus arctos) shoulder meat (musculus triceps brachii) using monoterpene-enriched alginate coatings

Abstract

This study presents the first detailed characterization of microbial succession in brown bear (Ursus arctos) shoulder meat during refrigerated vacuum storage and the first evaluation of the modulating effects of pure monoterpenes applied via alginate coatings. Vacuum-packaged meat was treated with sodium alginate coatings containing monoterpenes (α-pinene, β-pinene, bornyl acetate, D-carvone, 3-carene, limonene, sabinene; 0.03% v/v) and stored at 4 °C for 7 days. Microbial dynamics were monitored by culture-based enumeration (log CFU g⁻¹) and species-level identification using MALDI-TOF MS. The initial microbiota, dominated by Enterobacteriaceae (50% on day 0, 71% on day 3), comprised the genera Escherichia, Enterobacter, Klebsiella, Serratia and Lelliottia. Vacuum storage led to complete elimination of obligate aerobic Pseudomonas and Acinetobacter by day 3, followed by a pronounced shift towards lactic acid bacteria (LAB), which accounted for 35% of the microbiota by day 7. Monoterpene-enriched coatings tended to result in higher LAB counts (5.09–5.16 log CFU g⁻¹) compared to the control (4.92 log CFU g⁻¹), indicating suppression of Gram-negative spoilage bacteria rather than broad antimicrobial inhibition. All 36 bacterial species isolated from bear meat exhibited complete susceptibility to tested antibiotics (inhibition zones 20.33–54.33 mm), providing useful baseline data on wildlife-associated microbiota unexposed to anthropogenic antibiotic pressure. These findings suggest that monoterpenes may act as selective modulators of microbial succession, highlighting their potential for controlled preservation.