The effects of simulated microgravity on two bacterial isolates, Sphingobacterium thalpophilium and Ralstonia pickettii (formerly Burkholderia pickettii), originally recovered from water systems aboard the Mir space station were examined. These bacteria were inoculated into water, high and low concentrations of nutrient broth and subjected to simulated microgravity conditions. S. thalpophilium (which was motile and had flagella) showed no significant differences between simulated microgravity and the normal gravity control regardless of the method of enumeration and medium. In contrast, for R. pickettii (that was non-motile and lacked flagella), there were significantly higher numbers in high nutrient broth under simulated microgravity compared to normal gravity. Conversely, when R. pikkettii was inoculated into water (i.e., starvation conditions) significantly lower numbers were found under simulated microgravity compared to normal gravity. Responses to microgravity depended on the strain used (e.g., the motile strain exhibited no response to microgravity, while the non-motile strain did), the method of enumeration, and the nutrient concentration of the medium. Under oligotrophic conditions, non-motile cells may remain in geostationary orbit and deplete nutrients in their vicinity, while in high nutrient medium, resources surrounding the cell may be sufficient so that high growth is observed until nutrients becoming limiting.

中文翻译：

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模拟微重力对和平号空间站细菌的影响。

考察了模拟微重力对最初从Mir太空站上的水系统中回收的两种细菌分离物，嗜盐鞘氨醇杆菌和Ralstonia pickettii（以前称为Burkholderia pickettii）的影响。将这些细菌接种到水中，高浓度和低浓度的营养肉汤中，并使其处于模拟微重力条件下。嗜盐链球菌（能运动并带有鞭毛）在模拟微重力和正常重力控制之间没有显着差异，而与枚举和培养基方法无关。相反，对于R. pickettii（不活动，缺乏鞭毛），与正常重力相比，在模拟微重力下高营养肉汤中的数量明显更高。相反，当将R. pikkettii接种到水中时（即，饥饿条件下），与正常重力相比，在模拟微重力下发现的数量要少得多。对微重力的响应取决于所使用的菌株（例如，运动菌株对微重力无反应，而非运动菌株对微重力没有反应），枚举方法和培养基中的营养物浓度。在贫营养条件下，非运动细胞可能保留在地球静止轨道中并耗尽其附近的养分，而在高营养培养基中，细胞周围的资源可能足够，因此可以观察到高生长，直到养分变得有限为止。而非运动型菌株则需要这样做），枚举方法和培养基中的营养成分。在贫营养条件下，非运动细胞可能保留在地球静止轨道中并耗尽其附近的养分，而在高营养培养基中，细胞周围的资源可能足够，因此可以观察到高生长，直到养分变得有限为止。而非运动型菌株则需要这样做），枚举方法和培养基中的营养成分。在贫营养条件下，非运动细胞可能保留在地球静止轨道中并耗尽其附近的养分，而在高营养培养基中，细胞周围的资源可能足够，因此可以观察到高生长，直到养分变得有限为止。