Mettler Madelyn K, Goemann Hannah M, Mueller Rebecca C, Vanegas Oscar A, Lopez Gabriela, Singh Nitin, Venkateswaran Kasthuri, Peyton Brent M
Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA.
Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA.
Biofilm. 2023 May 13;5:100127. doi: 10.1016/j.bioflm.2023.100127. eCollection 2023 Dec.
While life on Mars has not been found, Earth-based microorganisms may contaminate the Red Planet during rover expeditions and human exploration. Due to the survival advantages conferred by the biofilm morphology to microorganisms, such as resistance to UV and osmotic stress, biofilms are particularly concerning from a planetary protection perspective. Modeling and data from the NASA Phoenix mission indicate that temporary liquid water might exist on Mars in the form of high salinity brines. These brines could provide colonization opportunities for terrestrial microorganisms brought by spacecraft or humans. To begin testing for potential establishment of microbes, results are presented from a simplified laboratory model of a Martian saline seep inoculated with sediment from Hailstone Basin, a terrestrial saline seep in Montana (USA). The seep was modeled as a sand-packed drip flow reactor at room temperature fed media with either 1 M MgSO or 1 M NaCl. Biofilms were established within the first sampling point of each experiment. Endpoint 16S rRNA gene community analysis showed significant selection of halophilic microorganisms by the media. Additionally, we detected 16S rRNA gene sequences highly similar to microorganisms previously detected in two spacecraft assembly cleanrooms. These experimental models provide an important foundation for identifying microbes that could hitch-hike on spacecraft and may be able to colonize Martian saline seeps. Future model optimization will be vital to informing cleanroom sterilization procedures.
虽然尚未在火星上发现生命，但在火星车探险和人类探索期间，地球上的微生物可能会污染这颗红色星球。由于生物膜形态赋予微生物生存优势，比如对紫外线和渗透胁迫的抗性，从行星保护的角度来看，生物膜尤其令人担忧。美国国家航空航天局（NASA）凤凰号任务的建模和数据表明，火星上可能存在以高盐卤水形式存在的临时液态水。这些卤水可能为航天器或人类携带的陆地微生物提供定殖机会。为了开始测试微生物潜在的定殖情况，我们展示了一个简化的实验室模型的测试结果，该模型模拟火星盐渍渗出地，并接种了来自美国蒙大拿州海石盆地（一个陆地盐渍渗出地）的沉积物。该渗出地在室温下被模拟为一个填充沙子的滴流反应器，向其中加入含有1M硫酸镁或1M氯化钠的培养基。在每个实验的第一个采样点就形成了生物膜。终点16S rRNA基因群落分析表明，培养基对嗜盐微生物有显著的选择作用。此外，我们检测到与之前在两个航天器组装洁净室中检测到的微生物高度相似的16S rRNA基因序列。这些实验模型为识别可能搭乘航天器并可能在火星盐渍渗出地定殖的微生物提供了重要基础。未来的模型优化对于指导洁净室灭菌程序至关重要。
