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Mapping the dominant microbial species diversity at expiration date of raw meat and processed meats from equine origin, an underexplored meat ecosystem, in the Belgian retail

Geeraerts, Wim, De Vuyst, Luc, Leroy, Frédéric
International journal of food microbiology 2019 v.289 pp. 189-199
Anoxybacillus, Brevibacterium, Brochothrix thermosphacta, Carnobacterium divergens, DNA, Hafnia alvei, Lactobacillus curvatus, Lactobacillus sakei, Lactococcus piscium, Leuconostoc gelidum, Staphylococcus equorum, bacterial communities, coagulase negative staphylococci, ecosystems, food consumption, genes, horse meat, horses, lactic acid bacteria, paper, processed meat, raw meat, ribosomal RNA, sequence analysis, species diversity, storage temperature, zebras
Although equine meats and their derived smoked or fermented products are popular in some regions of the world, they only form a minor fraction of the global meat consumption. The latter may explain why their associated bacterial communities have not received much attention. In the present study, 69 different samples of equine meats and meat products were investigated. The samples consisted of raw meat from horses (17 samples) and zebra (7), as well as non-fermented but smoked (24) and fermented (21) horse meat products. After purchase, all samples were stored at 4 °C and analysed at expiration date. Besides an estimation of the total microbial counts, specific attention was paid to the identification of lactic acid bacteria (LAB) and catalase-positive cocci, in particular the group of coagulase-negative staphylococci (CNS), involved, due to their technological relevance in view of the elaboration of meat products. Samples that were loosely wrapped in butcher paper instead of vacuum- or modified-atmosphere packages were also screened for pseudomonads and enterobacterial species. In total, 1567 bacterial isolates were collected, subjected to (GTG)5-PCR fingerprinting of genomic DNA, and identified by multiple gene sequencing (based on the 16S rRNA, pheS, rpoA, rpoB, and/or tuf genes). Overall, the bacterial species diversity consisted mostly of LAB but was contingent on the type of product. Raw meat was dominated by Carnobacterium divergens, Lactobacillus sakei, Lactococcus piscium, and Leuconostoc gelidum, with zebra meat being particularly rich in lactococci. Smoked and fermented horse meat products contained mostly Lb. sakei and, to a lesser degree, Lactobacillus curvatus. In addition, several catalase-positive cocci (mostly Staphylococcus equorum), Anoxybacillus sp., Brevibacterium sp., Brochothrix thermosphacta, and the enterobacterial species Hafnia alvei were found.