Cultures of Escherichia coli grown in space reached a 25% higher average final cell population than those in comparably matched ground controls (p<0.05). However, both groups consumed the same quantity of glucose, which suggests that space flight not only stimulated bacterial growth as has been previously reported, but also resulted in a 25% more efficient utilization of the available nutrients. Supporting experiments performed in "simulated weightlessness" under clinorotation produced similar trends of increased growth and efficiency, but to a lesser extent in absolute values. These experiments resulted in increases of 12% and 9% in average final cell population (p<0.05), while the efficiency of substrate utilization improved by 6% and 9% relative to static controls (p=0.12 and p<0.05, respectively). In contrast, hypergravity, produced by centrifugation, predictably resulted in the opposite effect--a decrease of 33% to 40% in final cell numbers with corresponding 29% to 40% lower net growth efficiencies (p<0.01). Collectively, these findings support the hypothesis that the increased bacterial growth observed in weightlessness is a result of reduced extracellular mass transport that occurs in the absence of sedimentation and buoyancy-driven convection, which consequently also improves substrate utilization efficiency in suspended cultures.

中文翻译：

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太空飞行，倾斜旋转和离心作用对大肠杆菌底物利用效率的影响。

在太空中生长的大肠杆菌培养物的平均最终细胞数比在相匹配的地面对照中高出25％（p <0.05）。但是，两组都消耗了相同数量的葡萄糖，这表明太空飞行不仅刺激了细菌的生长，如先前报道的那样，而且还使有效营养素的利用效率提高了25％。在倾斜旋转下以“模拟失重”进行的辅助实验产生了相似的增长和效率增长趋势，但绝对值的程度较小。这些实验导致平均最终细胞数增加12％和9％（p <0.05），而底物利用效率相对于静态对照提高了6％和9％（分别为p = 0.12和p <0.05） 。相比之下，超重力 离心产生的蛋白质可预期产生相反的效果-最终细胞数量减少33％至40％，而净生长效率相应降低29％至40％（p <0.01）。总的来说，这些发现支持这样的假说：在失重状态下观察到的细菌生长增加是由于细胞外传质减少而导致的，这种现象是在没有沉淀和浮力驱动的对流的情况下发生的，因此还提高了悬浮培养物中底物的利用效率。