背景：
从国际空间站（ISS）分离的5株肠杆菌菌株的抗菌素耐药性（AMR）表型特性，多重耐药性（MDR）基因谱以及与潜在毒力和致病性相关的基因进行了比较，并与3个基因组进行了比较。临床菌株。使用Nanopore和Illumina读数的杂合从头组装表征ISS菌株的全基因组序列。除了传统的微生物分类学方法，还进行了多位点序列分型（MLST）分析以对系统发育谱系进行分类。进行琼脂扩散盘测定以测试抗生素易感性。组装和搭建后的基因组草图使用子系统技术和RNAmmer服务器的快速注释进行注释，用于下游分析。

结果：
所有公开肠杆菌基因组的ISS菌株的分子系统发育和全基因组分析显示，ISS菌株是E. bugandensis，类似于菌株EB-247T和两种临床分离株（153_ECLO和MBRL 1077）。所有8种E. bungandensis菌株的比较基因组分析显示，共有4733个基因与碳水化合物代谢（635个基因），氨基酸和衍生物（496个基因），蛋白质代谢（291个基因），辅助因子，维生素，辅助组，色素（275个基因），膜转运（247个基因）和RNA代谢（239个基因）。此外，在ISS菌株中鉴定的112个基因参与毒力，疾病和防御。在ISS菌株中也鉴定出与抗生素和有毒化合物抗性相关的基因，包括MDR三联体系。在ISS菌株中也观察到多重抗生素抗性（MAR）基因座或编码MarA，MarB，MarC和MarR的MAR操纵子，其调节60多个基因，包括在大肠杆菌K12中报道的药物外排系统的上调。 。

结论：
鉴于这些ISS肠杆菌基因组的MDR结果和致病性增加的机会（PathogenFinder算法概率> 79％），这些物种为未来的任务提出了重要的健康考虑因素。从ISS分离的菌株的完整基因组特征可以帮助理解致病潜力，并为未来的任务提供信息，但是需要在体内系统中分析它们以辨别微重力对其致病性的影响。

BACKGROUND:
The antimicrobial resistance (AMR) phenotypic properties, multiple drug resistance (MDR) gene profiles, and genes related to potential virulence and pathogenic properties of five Enterobacter bugandensis strains isolated from the International Space Station (ISS) were carried out and compared with genomes of three clinical strains. Whole genome sequences of ISS strains were characterized using the hybrid de novo assembly of Nanopore and Illumina reads. In addition to traditional microbial taxonomic approaches, multilocus sequence typing (MLST) analysis was performed to classify the phylogenetic lineage. Agar diffusion discs assay was performed to test antibiotics susceptibility. The draft genomes after assembly and scaffolding were annotated with the Rapid Annotations using Subsystems Technology and RNAmmer servers for downstream analysis.

RESULTS:
Molecular phylogeny and whole genome analysis of the ISS strains with all publicly available Enterobacter genomes revealed that ISS strains were E. bugandensis and similar to the type strain EB-247T and two clinical isolates (153_ECLO and MBRL 1077). Comparative genomic analyses of all eight E. bungandensis strains showed, a total of 4733 genes were associated with carbohydrate metabolism (635 genes), amino acid and derivatives (496 genes), protein metabolism (291 genes), cofactors, vitamins, prosthetic groups, pigments (275 genes), membrane transport (247 genes), and RNA metabolism (239 genes). In addition, 112 genes identified in the ISS strains were involved in virulence, disease, and defense. Genes associated with resistance to antibiotics and toxic compounds, including the MDR tripartite system were also identified in the ISS strains. A multiple antibiotic resistance (MAR) locus or MAR operon encoding MarA, MarB, MarC, and MarR, which regulate more than 60 genes, including upregulation of drug efflux systems that have been reported in Escherichia coli K12, was also observed in the ISS strains.

CONCLUSION:
Given the MDR results for these ISS Enterobacter genomes and increased chance of pathogenicity (PathogenFinder algorithm with > 79% probability), these species pose important health considerations for future missions. Thorough genomic characterization of the strains isolated from ISS can help to understand the pathogenic potential, and inform future missions, but analyzing them in in-vivo systems is required to discern the influence of microgravity on their pathogenicity.

https://www.ncbi.nlm.nih.gov/pubmed/30466389