Regenerative life support systems (RLSS) will play a vital role in achieving self-sufficiency during long-distance space travel. Urine conversion into a liquid nitrate-based fertilizer is a key process in most RLSS. This study describes the effects of simulated microgravity (SMG) on Comamonas testosteroni, Nitrosomonas europaea, Nitrobacter winogradskyi and a tripartite culture of the three, in the context of nitrogen recovery for the Micro-Ecological Life Support System Alternative (MELiSSA). Rotary cell culture systems (RCCS) and random positioning machines (RPM) were used as SMG analogues. The transcriptional responses of the cultures were elucidated. For CO₂-producing C. testosteroni and the tripartite culture, a PermaLife^TM PL-70 cell culture bag mounted on an in-house 3D-printed holder was applied to eliminate air bubble formation during SMG cultivation. Gene expression changes indicated that the fluid dynamics in SMG caused nutrient and O₂ limitation. Genes involved in urea hydrolysis and nitrification were minimally affected, while denitrification-related gene expression was increased. The findings highlight potential challenges for nitrogen recovery in space.

再生生命支持系统（RLSS）将在长途太空旅行中实现自给自足方面发挥至关重要的作用。将尿液转化为液体硝酸盐肥料是大多数 RLSS 的关键过程。本研究描述了在微生态生命支持系统替代方案 (MELiSSA) 氮回收的背景下，模拟微重力 (SMG) 对睾丸酮丛毛单胞菌、欧洲亚硝化单胞菌、维氏硝化杆菌以及三者三方培养物的影响。旋转细胞培养系统 (RCCS) 和随机定位机 (RPM) 被用作 SMG 类似物。阐明了培养物的转录反应。对于产生CO _2的睾丸酮梭菌和三方培养，使用安装在内部3D打印支架上的PermaLife ^{TM PL-70细胞培养袋来消除SMG培养期间气泡的形成。}基因表达变化表明SMG 中的流体动力学导致营养和O ₂限制。参与尿素水解和硝化作用的基因受到的影响最小，而反硝化相关基因的表达则有所增加。研究结果凸显了太空中氮回收的潜在挑战。