Zea Luis, Larsen Michael, Estante Frederico, Qvortrup Klaus, Moeller Ralf, Dias de Oliveira Sílvia, Stodieck Louis, Klaus David
BioServe Space Technologies, University of Colorado Boulder, BoulderCO, United States.
Department of Biomedical Sciences, University of CopenhagenCopenhagen, Denmark.
Front Microbiol. 2017 Aug 28;8:1598. doi: 10.3389/fmicb.2017.01598. eCollection 2017.
Bacteria will accompany humans in our exploration of space, making it of importance to study their adaptation to the microgravity environment. To investigate potential phenotypic changes for bacteria grown in space, was cultured onboard the International Space Station with matched controls on Earth. Samples were challenged with different concentrations of gentamicin sulfate to study the role of drug concentration on the dependent variables in the space environment. Analyses included assessments of final cell count, cell size, cell envelope thickness, cell ultrastructure, and culture morphology. A 13-fold increase in final cell count was observed in space with respect to the ground controls and the space flight cells were able to grow in the presence of normally inhibitory levels of gentamicin sulfate. Contrast light microscopy and focused ion beam/scanning electron microscopy showed that, on average, cells in space were 37% of the volume of their matched controls, which may alter the rate of molecule-cell interactions in a diffusion-limited mass transport regime as is expected to occur in microgravity. TEM imagery showed an increase in cell envelope thickness of between 25 and 43% in space with respect to the Earth control group. Outer membrane vesicles were observed on the spaceflight samples, but not on the Earth cultures. While suspension cultures on Earth were homogenously distributed throughout the liquid medium, in space they tended to form a cluster, leaving the surrounding medium visibly clear of cells. This cell aggregation behavior may be associated with enhanced biofilm formation observed in other spaceflight experiments.
在人类探索太空的过程中，细菌将一直伴随左右，因此研究它们对微重力环境的适应性具有重要意义。为了探究在太空生长的细菌可能出现的表型变化，在国际空间站上对细菌进行了培养，并在地球上设置了匹配的对照组。用不同浓度的硫酸庆大霉素对样本进行处理，以研究药物浓度在太空环境中对因变量的作用。分析内容包括对最终细胞计数、细胞大小、细胞包膜厚度、细胞超微结构和培养形态的评估。与地面对照组相比，在太空中观察到最终细胞计数增加了13倍，并且太空飞行的细胞能够在通常具有抑制作用的硫酸庆大霉素浓度下生长。相差光学显微镜和聚焦离子束/扫描电子显微镜显示，平均而言，太空中的细胞体积仅为其匹配对照组的37%，这可能会改变在扩散限制的质量传输机制下分子与细胞相互作用的速率，而这种情况预计会在微重力环境中发生。透射电子显微镜图像显示，与地球对照组相比，太空中细胞包膜厚度增加了25%至43%。在太空飞行样本中观察到了外膜囊泡，但在地球培养物中未观察到。地球上的悬浮培养物在整个液体培养基中均匀分布，而在太空中它们倾向于形成团簇，使得周围培养基中明显没有细胞。这种细胞聚集行为可能与其他太空飞行实验中观察到的生物膜形成增强有关。
