Hula Research Center, Department of Animal Sciences, Tel-Hai Academic College, Tel Hai, Israel.
Hula Research Center, Department of Biotechnology, Tel-Hai Academic College, Tel Hai, Israel.
Sci Rep. 2024 Aug 14;14(1):18904. doi: 10.1038/s41598-024-69942-y.
Detecting life has driven research and exploration for centuries, but recent attempts to compile and generate a framework that summarizes life features, aimed to develop strategies for life detection missions beyond planet Earth, have disregarded a key life feature: behavior. Yet, some behaviors such as biomineralization or motility have occasionally been proposed as biosignatures to detect life. Here, we capitalize on a specific taxis' motility behavior, magnetotaxis, to experimentally provide insights in support of behavior as an unambiguous, sensitive biosignature, and magnetic forces as a prescreening option. Using a magnetotactic bacterial species, Magnetospirillum magneticum, we conducted a lab sensitivity experiment comparing PCR with the hanging drop behavioral assay, using a dilution series. The hanging drop behavioral assay visually shows the motility of MTB toward magnetic poles. Our findings reveal that the behavioral assay exhibits higher sensitivity in the detection of M. magneticum when compared to the established PCR protocol. While both methods present similar detection sensitivities at high concentrations, at ≥ 10 fold dilutions, the behavioral method proved more sensitive. The behavioral method can detect bacteria even when samples are diluted at 10. Comparable results were obtained with environmental samples from the Hula Valley. We propose behavioral cues as valuable biosignatures in the ongoing efforts of life detection in unexplored aquatic habitats on Earth and to stimulate and support discussions about how to detect extant life beyond Earth. Generic and robust behavioral assays can represent a methodological revolution.
探测生命的存在一直是几个世纪以来研究和探索的主题，但是最近为了制定在地球以外的星球上探测生命的任务的策略，人们尝试编写和生成一个总结生命特征的框架，然而却忽略了一个关键的生命特征：行为。然而，一些行为，如生物矿化或运动性，偶尔被提议作为生物特征来探测生命。在这里，我们利用一种特定的趋性行为——趋磁性，通过实验提供了支持行为作为一种明确、敏感的生物特征的见解，以及磁场作为一种预筛选选项。我们使用趋磁细菌 Magnetospirillum magneticum 进行了一项实验室灵敏度实验，比较了聚合酶链式反应（PCR）和悬滴行为检测法，使用了一系列稀释度。悬滴行为检测法可以直观地显示 MTB 向磁极的运动性。我们的研究结果表明，与已建立的 PCR 方案相比，行为检测法在检测 M. magneticum 时具有更高的灵敏度。虽然这两种方法在高浓度下都具有相似的检测灵敏度，但在稀释度≥10 倍时，行为方法的灵敏度更高。即使将样本稀释到 10 倍，行为方法也可以检测到细菌。在胡拉谷的环境样本中也得到了类似的结果。我们提出行为线索是探测地球未探索的水生栖息地中生命的有价值的生物特征，并激发和支持关于如何在地球以外探测现存生命的讨论。通用且稳健的行为检测法可以代表一种方法学的革命。
