Data Sheet 5_Genome organization, virulence genes, and temperature-dependent motility of an emerging pathogen, Escherichia marmotae.xlsx

IntroductionEscherichia marmotae is one of the Escherichia cryptic clades that were first isolated from animal feces and environmental waters and has recently emerged as an organism of concern due to its presence in human infections. Although E. marmotae cannot be distinguished from E. coli by standard clinical tests, its 10% pairwise genomic difference from E. coli led us to investigate other phenotypic differences that may be present.
MethodsBioinformatic software was used to identify the E. marmotae pan-genome, antimicrobial and virulence genes, and sequences of genes for motility, biofilm formation, and other phenotypic characteristics. Environmental and clinical isolates of E. marmotae were analyzed for antimicrobial sensitivity, and for temperature effects on motility, growth, and biofilm formation, in comparison to E. coli. RT-PCR analyzed associated changes in gene expression.
ResultsThe E. marmotae genome consists of >75% core genes, and has many accessory genes, including plasmids and antimicrobial resistance genes. E. marmotae is resistant to erythromycin. E. marmotae had all genes needed for complete flagellar gene assembly, and phenotypically was motile at 28°C, and much less motile at 37°C. More biofilm formation was observed at 28°C than at 37°C. The expression of motility genes motA and fliA decreased at 37°C in E. marmotae compared to E. coli.
ConclusionThese temperature-sensitive traits may support environmental persistence and adaptations that may facilitate E. marmotae to cause human disease.

引言：旱獭埃希菌（Escherichia marmotae）属于埃希菌隐秘进化枝之一，最初分离自动物粪便与环境水体，近期因在人类感染病例中被检出而成为受关注的微生物。尽管通过标准临床检测无法将旱獭埃希菌与大肠杆菌（E. coli）区分开来，但二者全基因组两两比对存在10%的序列差异，这促使我们对其潜在的其他表型差异展开研究。
材料与方法：利用生物信息学软件解析旱獭埃希菌的泛基因组、抗菌基因与毒力基因，以及运动性、生物被膜形成等相关表型特征的基因序列。以大肠杆菌为对照，对旱獭埃希菌的环境分离株与临床分离株开展抗菌敏感性检测，并分析温度对其运动性、生长及生物被膜形成的影响。通过逆转录聚合酶链反应（RT-PCR）检测相关基因的表达变化。
结果：旱獭埃希菌的基因组中核心基因占比超过75%，同时携带大量附属基因，包括质粒与抗菌耐药基因。该菌对红霉素具有耐药性。旱獭埃希菌拥有完整鞭毛组装所需的全部基因，表型实验显示其在28℃时具备运动能力，而在37℃时运动能力显著降低。相较于37℃，28℃条件下其生物被膜形成量更高。与大肠杆菌相比，旱獭埃希菌在37℃时运动相关基因motA与fliA的表达量出现下调。
结论：这些温度敏感表型或许有助于旱獭埃希菌在环境中存续与适应，进而可能促进其引发人类感染疾病。