INRA, UMR1319 Micalis, F-78350 Jouy-en-Josas, France; AgroParisTech, UMR Micalis, F-78350 Jouy-en-Josas, France.
Food Microbiol. 2012 Apr;29(2):187-96. doi: 10.1016/j.fm.2011.08.001. Epub 2011 Aug 12.
We have investigated the population structure of lactic acid bacteria (LAB) for several beef carpaccio available on the market with the purpose of comparing the effect of storage process (modified-atmosphere packaging and vacuum-packaging) and of seasonal changes on this microbial population. Out of 60 samples we have characterised 214 isolates accounting for 10 LAB species and 35 isolates accounting for 11 non-LAB species. Lactobacillus sakei, Leuconostoc carnosum and Leuconostoc mesenteroides were the most prevailing LAB species with a frequency of identification within 66%, 62% and 52% of the samples respectively. These 3 species were also characterised by a phenotypic intra-species diversity of isolates based on colony morphology. We showed that the prevalence was increased 1.5 fold for L. sakei and L. mesenteroides during the summer sampling in comparison to the spring or the fall sampling suggesting an environmental origin of these two species. Seasonal variations were also observed for the prevalence of Lactobacillus fuchuensis and L. carnosum in spring (2- and 1.5-fold increase, respectively) and of Brochothrix thermosphacta in fall (6-fold increase). Finally, we demonstrated that the growth potential after the sell-by-date was favourable of 1.25 log(10) cfu g(-1) to Leuconostoc spp. in modified-atmosphere packaging and of 1.38 log(10) cfu g(-1) to Lactobacillus spp. in vacuum-packaging. In conclusion, we show that important and unsuspected traits in bacterial population dynamics can be unravelled by large sampling strategies. We discuss about the need to take this assessment into account for further studies on bacterial ecosystems of meat.
我们调查了市售几种生牛肉薄片中乳酸菌（LAB）的种群结构，目的是比较贮藏过程（改良气氛包装和真空包装）和季节变化对这种微生物种群的影响。在 60 个样本中，我们共鉴定出 214 个分离株，代表 10 种 LAB 和 11 种非 LAB 种。乳杆菌（Lactobacillus sakei）、肠膜明串珠菌（Leuconostoc carnosum）和肠系膜明串珠菌（Leuconostoc mesenteroides）是最普遍的 LAB 种，在 66%、62%和 52%的样本中分别鉴定出这 3 种。这 3 种还表现出基于菌落形态的分离株表型种内多样性。我们表明，与春季或秋季采样相比，夏季采样时 L. sakei 和 L. mesenteroides 的流行率增加了 1.5 倍，表明这两种菌具有环境来源。在春季，还观察到福氏乳杆菌（Lactobacillus fuchuensis）和肠膜明串珠菌（L. carnosum）的流行率增加了 2 倍和 1.5 倍，在秋季，也观察到生孢梭菌（Brochothrix thermosphacta）的流行率增加了 6 倍。最后，我们证明，在改良气氛包装中，Leuconostoc spp.在保质期后仍有良好的生长潜力，可增加 1.25 log(10) cfu g(-1)，在真空包装中，Lactobacillus spp.可增加 1.38 log(10) cfu g(-1)。总之，我们表明，通过大规模采样策略，可以揭示细菌种群动态中重要且未被察觉的特征。我们讨论了需要将这种评估纳入对肉类细菌生态系统的进一步研究中。
