Department of Food Science, Cornell Universitygrid.5386.8, Ithaca, New York, USA.
Department of Microbiology, Cornell Universitygrid.5386.8, Ithaca, New York, USA.
Microbiol Spectr. 2022 Jun 29;10(3):e0044222. doi: 10.1128/spectrum.00442-22. Epub 2022 Jun 6.
Soil samples collected in the Great Smoky Mountains National Park yielded a isolate that could not be classified to the species level. Whole-genome sequence-based average nucleotide identity BLAST and DNA-DNA Hybridization analyses confirmed this isolate to be a novel species with the highest similarity to (ANI = 93.9%, isDDH = 55.9%). Additional whole-genome-based analysis using the Genome Taxonomy Database Toolkit further supported delineation as a novel species, as this tool failed to assign a species identification. Phenotypic and genotypic characterization results indicate that this species is nonpathogenic. Specifically, the novel species described here is phenotypically (i) nonhemolytic and (ii) negative for phosphatidylinositol-specific phospholipase C activity; the draft genome lacks all virulence genes found in the pathogenicity islands 1, 2, 3, and 4 as well as the internalin genes and . While the type strain contains an apparently intact catalase gene (), this strain is phenotypically catalase-negative (an unusual characteristic for species). Additional analyses identified a nonsynonymous mutation in a conserved codon of that is likely linked to the catalase-negative phenotype. Rapid species identification systems, including two biochemical and one matrix-assisted laser desorption/ionization, misidentified this novel species as either L. monocytogenes or . We propose the name and the type strain is FSL L7-0020 (=ATCC TSD-239). is a novel species that originated from a US National Park and it will be the first identified to date without official standing in the nomenclature. Validation was impeded by the National Park's requirements for strain access, ultimately deemed too restrictive by the International Committee on Systematics of Prokaryotes. However, lack of valid status should not detract from the significance of adding a novel species to the clade. Notably, detection of non species in a food processing environment indicate conditions that could facilitate the presence of the pathogen L. monocytogenes. If isolated, our data show a potential for to be misidentified as another notably L. monocytogenes. Therefore, developers of spp. detection and identification methods, who historically only include validly published species in their validation studies, should include to ensure accurate results.
从大烟山国家公园采集的土壤样本中分离出一株无法归类到种水平的菌株。全基因组序列平均核苷酸同一性 BLAST 和 DNA-DNA 杂交分析结果证实，该菌株是一个新种，与亲缘关系最近的物种 （ANI = 93.9%，isDDH = 55.9%）相似度最高。利用基因组分类数据库工具进行的全基因组分析进一步支持了其作为新种的划分，因为该工具无法确定种属。表型和基因型特征表明，该菌株是非致病性的。具体来说，这里描述的新 种表型上：（i）不溶血；（ii）磷脂酰肌醇特异性磷脂酶 C 活性阴性；基因组草图中缺乏在致病性岛 1、2、3 和 4 以及内毒素基因 和 中发现的所有毒力基因。虽然模式菌株含有一个明显完整的过氧化氢酶基因 ()，但该菌株表型上过氧化氢酶阴性（这是 种属的一个不寻常特征）。进一步的分析确定了 中一个保守密码子的非同义突变，这可能与过氧化氢酶阴性表型有关。包括两种生化和一种基质辅助激光解吸/电离快速鉴定系统，将这种新的菌株误鉴定为单核细胞增生李斯特菌或 。我们建议将其命名为 ，其模式菌株为 FSL L7-0020（=ATCC TSD-239）。 是一种新的 种属，起源于美国国家公园，它将是第一个没有正式分类地位的被识别的种属。由于国家公园对菌株访问的要求，验证工作受到阻碍，最终被国际系统学委员会认为过于严格。然而，缺乏有效地位不应减损将一个新的种属添加到 进化枝的重要性。值得注意的是，在食品加工环境中检测到非 种属表明，存在李斯特菌的条件可能有利于其生存。如果分离出来，我们的数据表明 有被错误鉴定为另一种 属的可能，尤其是单核细胞增生李斯特菌。因此， 属检测和鉴定方法的开发者，他们在验证研究中只包括已正式发表的有效种属，应该包括 ，以确保结果的准确性。
