Department of Microbiology and Cell Science, IFAS, University of Florida, Gainesville, Florida, USA.
Department of Biological Sciences, Florida Gulf Coast University, Fort Myers, Florida, USA.
J Bacteriol. 2024 Sep 19;206(9):e0027224. doi: 10.1128/jb.00272-24. Epub 2024 Aug 9.
is commonly isolated from astronauts returning from spaceflight. Previous analysis of omics data from low Earth orbit cultures indicated significantly increased expression of the Agr quorum sensing system and its downstream targets in spaceflight samples compared to ground controls. In this current study, the rotary cell culture system (RCCS) was used to investigate the effect of low-shear modeled microgravity (LSMMG) on physiology and Agr activity. When cultured in the same growth medium and temperature as the previous spaceflight experiment, LSMMG cultures exhibited decreased expression and altered growth compared to normal gravity control cultures, which are typically oriented with oxygenation membrane on the bottom of the high aspect rotating vessel (HARV). When was grown in an inverted gravity control orientation (oxygenation membrane on top of the HARV), reduced Agr activity was observed relative to both traditional control and LSMMG cultures, signifying that oxygen availability may affect the observed differences in Agr activity. Metabolite assays revealed increased lactate and decreased acetate excretion in both LSMMG and inverted control cultures. Secretomics analysis of LSMMG, control, and inverted control HARV culture supernatants corroborated these results, with inverted and LSMMG cultures exhibiting a decreased abundance of Agr-regulated virulence factors and an increased abundance of proteins expressed in low-oxygen conditions. Collectively, these studies suggest that the orientation of the HARV oxygenation membrane can affect physiology and Agr quorum sensing in the RCCS, a variable that should be considered when interpreting data using this ground-based microgravity model.IMPORTANCE is commonly isolated from astronauts returning from spaceflight and from surfaces within human-inhabited closed environments such as spacecraft. Astronaut health and immune function are significantly altered in spaceflight. Therefore, elucidating the effects of microgravity on physiology is critical for assessing its pathogenic potential during long-term human space habitation. These results also highlight the necessity of eliminating potential confounding factors when comparing simulated microgravity model data with actual spaceflight experiments.
常从返回太空的宇航员身上分离出来。先前对低地球轨道培养物的组学数据分析表明，与地面对照相比，航天样本中 Agr 群体感应系统及其下游靶标的表达显著增加。在本研究中，旋转细胞培养系统 (RCCS) 用于研究低剪切模拟微重力 (LSMMG) 对生理和 Agr 活性的影响。当在与先前太空飞行实验相同的生长培养基和温度下培养时，与正常重力对照培养物相比，LSMMG 培养物的表达减少且生长改变，而正常重力对照培养物通常以高纵横比旋转容器 (HARV) 底部的氧合膜定向培养。当在倒置重力对照方向（HARV 顶部的氧合膜）中生长时，与传统对照和 LSMMG 培养物相比，观察到 Agr 活性降低，这表明氧气可用性可能影响 Agr 活性观察到的差异。代谢物测定显示 LSMMG 和倒置对照培养物中乳酸排泄增加，乙酸盐排泄减少。LSMMG、对照和倒置对照 HARV 培养物上清液的分泌组学分析证实了这些结果，倒置和 LSMMG 培养物表现出 Agr 调节毒力因子的丰度降低，以及在低氧条件下表达的蛋白质的丰度增加。总之，这些研究表明，HARV 氧合膜的定向可以影响 RCCS 中的生理和 Agr 群体感应，在使用这种基于地面的微重力模型解释数据时，应考虑该变量。
重要的是，它通常从返回太空的宇航员身上以及航天器等载人密闭环境中的表面分离出来。在太空中，宇航员的健康和免疫功能会发生显著变化。因此，阐明微重力对生理的影响对于评估其在长期人类太空居住期间的致病潜力至关重要。这些结果还强调了在将模拟微重力模型数据与实际太空飞行实验进行比较时，消除潜在混杂因素的必要性。
