Bechtel Tyler D, Gibbons John G
Department of Food Science, University of Massachusetts, Amherst, MA, United States.
Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA, United States.
Front Microbiol. 2021 Feb 9;12:620033. doi: 10.3389/fmicb.2021.620033. eCollection 2021.
is the major causative agent of the foodborne illness listeriosis. Listeriosis presents as flu-like symptoms in healthy individuals, and can be fatal for children, elderly, pregnant women, and immunocompromised individuals. Estimates suggest that results in ∼1,600 illnesses and ∼260 deaths annually in the United States. can survive and persist in a variety of harsh environments, including conditions encountered in production of fermented dairy products such as cheese. For instance, microbial growth is often limited in soft cheese fermentation because of harsh pH, water content, and salt concentrations. However, has caused a number of deadly listeriosis outbreaks through the contamination of cheese. The purpose of this study was to understand if genetically distinct populations of are associated with particular foods, including cheese and dairy. To address this goal, we analyzed the population genetic structure of 504 strains isolated from food with publicly available genome assemblies. We identified 10 genetically distinct populations spanning lineages 1, II, and III and serotypes 1/2a, 1/2b, 1/2c, 4b, and 4c. We observed an overrepresentation of isolates from specific populations with cheese (population 2), fruit/vegetable (population 2), seafood (populations 5, 8 and 9) and meat (population 10). We used the Large Scale Blast Score Ratio pipeline and Roary to identify genes unique to population 1 and population 2 in comparison with all other populations, and screened for the presence of antimicrobial resistance genes and virulence genes across all isolates. We identified > 40 genes that were present at high frequency in population 1 and population 2 and absent in most other isolates. Many of these genes encoded for transcription factors, and cell surface anchored proteins. Additionally, we found that the virulence genes and were entirely or partially deleted in population 2. These results indicate that some populations may exhibit associations with particular foods, including cheese, and that gene content may contribute to this pattern.
是食源性李斯特菌病的主要病原体。李斯特菌病在健康个体中表现为类似流感的症状，对儿童、老年人、孕妇和免疫功能低下的个体可能是致命的。据估计，在美国，每年因 导致约1600例疾病和约260例死亡。 能够在各种恶劣环境中存活和持续存在，包括在发酵乳制品（如奶酪）生产过程中遇到的条件。例如，由于苛刻的pH值、水分含量和盐浓度，微生物生长在软奶酪发酵过程中通常受到限制。然而， 已通过奶酪污染引发了多起致命的李斯特菌病疫情。本研究的目的是了解基因上不同的 群体是否与特定食物（包括奶酪和乳制品）有关。为了实现这一目标，我们分析了从食品中分离的504株 菌株的群体遗传结构，并利用公开可用的基因组组装数据。我们鉴定出了跨越谱系I、II和III以及血清型1/2a、1/2b、1/2c、4b和4c的10个基因上不同的群体。我们观察到来自特定群体的分离株在奶酪（群体2）、水果/蔬菜（群体2）、海鲜（群体5、8和9）和肉类（群体10）中占比过高。我们使用大规模比对得分率管道和Roary来鉴定群体1和群体2相对于所有其他群体独特的基因，并筛选所有分离株中抗菌抗性基因和毒力基因的存在情况。我们鉴定出在群体1和群体2中高频存在而在大多数其他分离株中不存在的40多个基因。这些基因中的许多编码转录因子和细胞表面锚定蛋白。此外，我们发现群体2中的毒力基因 和 被完全或部分删除。这些结果表明，一些 群体可能与特定食物（包括奶酪）存在关联，并且基因内容可能促成了这种模式。
