Université de Lorraine, LIBio, Nancy, France.
Laboratoire de Biotechnologies Appliquées, EDST, Université Libanaise, Tripoli, Lebanon.
J Appl Microbiol. 2019 Feb;126(2):377-387. doi: 10.1111/jam.14127. Epub 2018 Nov 22.
Carnobacterium maltaromaticum is a lactic acid bacterium of technological interest in the field of dairy ripening and food bioprotection and is generally recognized as safe in the United States. As it is associated with fish infections, the European Food Safety Agency did not include this species in the qualified presumption safety list of micro-organisms. This implies that the risk assessment for the species has to be performed at the strain level.
Multilocus sequence typing (MLST) is a tool that (i) potentially allows to discriminate strains isolated from diseased fish from apathogenic strains and (ii) to assess the genetic relatedness between both groups of strains. In this study, we characterized by MLST 21 C. maltaromaticum strains including 16 strains isolated from diseased fish and 5 apathogenic dairy strains isolated from cheese. The resulting population structure was investigated by integrating these new data to the previously published population structure (available at http://pubmlst.org), which represents an overall of 71 strains.
This analysis revealed that none of the strains isolated from diseased fish is assigned to a clonal complex containing cheese isolates, and that 11 strains exhibit singleton genotypes suggesting that the population of diseased fish isolates is not clonal.
This study thus provides a population structure of C. maltaromaticum that could serve in the future as a reference that could contribute to the risk assessment of C. maltaromaticum strains intended to be used in the food chain.
片球菌（Carnobacterium maltaromaticum）是一种在乳制品成熟和食品生物保护领域具有技术应用价值的乳酸细菌，在美国被普遍认为是安全的。由于它与鱼类感染有关，欧洲食品安全局（European Food Safety Agency）没有将该物种列入微生物合格推定安全性清单。这意味着必须在菌株水平上对该物种进行风险评估。
多位点序列分型（MLST）是一种工具，（i）有可能区分从患病鱼类中分离出的菌株与非致病性菌株，（ii）评估这两组菌株之间的遗传相关性。在这项研究中，我们通过 MLST 对 21 株 C. maltaromaticum 菌株进行了特征描述，包括 16 株从患病鱼类中分离出的菌株和 5 株从奶酪中分离出的非致病性乳制品菌株。通过将这些新数据整合到之前发表的群体结构中（可在 http://pubmlst.org 上获得），研究了由此产生的种群结构，该结构代表了总共 71 株菌株。
该分析表明，从患病鱼类中分离出的菌株没有一个属于含有奶酪分离株的克隆复合体，并且有 11 株表现出单型基因型，这表明患病鱼类分离株的种群不是克隆的。
因此，本研究提供了 C. maltaromaticum 的种群结构，未来可以作为参考，有助于对拟用于食物链的 C. maltaromaticum 菌株进行风险评估。
