石碑可能是艰难的生活环境,特别是关于液态水的访问。然而,在他们身上发现了明显的微生物群落。已经提出了各种获取液态水的策略。不管它们的保水机制细节如何,虽然,我们认为水活度(细胞活力的关键指标)受到环境条件的限制,很大程度上独立于社区结构,并由当地温度和相对湿度预测。然而,直接测量SAB中的水活度,特别是那些生长在石头表面的,很难。提出了一种估算SAB内水分活度的方法,该方法使用保守采样的微创组合,天气数据,共焦成像,和数学建模。将该方法应用于联邦大厅国家纪念馆和托马斯·杰斐逊纪念馆的大理石屋顶的测量,在大约一年的时间内,对其地下石材社区的水活动进行了估算。
Stone monuments can be difficult environments for life, particularly with respect to liquid water access. Nevertheless, microbial communities are found on them with apparent ubiquity. A variety of strategies for access to liquid water have been proposed. Regardless of their water-retention mechanisms details, though, we argue that water activity (a key indicator for cell viability) is constrained by environmental conditions, largely independently of community structure, and is predicted by the local temperature and relative humidity. However, direct measurement of water activity in SABs, particularly those growing on stone surfaces, is difficult. A method for estimating water activity within SABs is presented that uses a minimally invasive combination of conservative sampling, weather data, confocal imaging, and mathematical modeling. Applying the methodology to measurements from the marble roofs of the Federal Hall National Memorial and of the Thomas Jefferson Memorial, estimations are made for water activity in their subaerial stone communities over the course of an approximately one year period.