Abstract Terrestrial basalts represent ecological niches with the potential for microbial habitability. However, little is known about how gradients of physical and/or chemical alteration may impact the distribution of microbial biomass. If higher abundances of microbial biomass are associated with identifiable alteration features, i.e. visible from orbit or rover, such features would become an important tool in the selection of astrobiology targets for future life-detection missions. To examine the associations between biomass abundance and basalt alteration processes, phospholipid fatty acid (PLFA) biomarker analysis was used to assess microbial biomass in basalts representative of distinct alteration categories collected from two Mars analog environments: Craters of the Moon National Monument and Preserve (COTM), Idaho and Hawai’i Volcanoes National Park (HVNP), Hawai’i. PLFA concentration was generally highest in field categorized high-temperature alteration (syn-emplacement) samples within COTM, particularly in those that may have also undergone some degree of secondary weathering. Basalts from HVNP showed more variable biomass abundances, with no clear trend between altered and unaltered basalts. HVNP fumarolic deposits (both active and relict fumarole-associated samples) generally had consistently detectable biomass although temperature appeared to play a role in abundance with the highest temperate fumarole exhibiting the lowest PLFA concentration. PLFA profiles generally had high proportions of brPLFA (including biomarkers of iron- and sulfur-reducing bacteria) and indicated that basalts were dominated by heterotrophic organisms, however no clear trend between community biomarker composition and alteration type or extent was identified. Heterogeneity of microbial biomass within terrestrial basalts suggests that identification of distinct alteration features clearly linked to high biomass (biomarkers) is challenging but that altered materials (syn-emplacement and secondary weathering) and fumarolic deposits are likely promising astrobiology targets.

中文翻译：

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各种改变玄武岩中的微生物群落分布：对天体生物学样本点选择的见解

摘要 陆地玄武岩代表了具有微生物宜居性潜力的生态位。然而，关于物理和/或化学变化的梯度如何影响微生物生物量的分布知之甚少。如果更高丰度的微生物生物量与可识别的改变特征相关，即从轨道或漫游车可见，这些特征将成为为未来生命探测任务选择天体生物学目标的重要工具。为了检查生物量丰度与玄武岩蚀变过程之间的关联，使用磷脂脂肪酸 (PLFA) 生物标志物分析来评估代表不同蚀变类别的玄武岩中的微生物生物量，这些生物量代表了从两个火星模拟环境收集的不同蚀变类别：月球国家纪念碑和保护区 (COTM) 陨石坑), 爱达荷州和夏威夷火山国家公园 (HVNP)，夏威夷。PLFA 浓度通常在 COTM 内的现场分类高温蚀变（同工位）样品中最高，特别是在那些可能也经历了一定程度的二次风化的样品中。来自 HVNP 的玄武岩显示出更多可变的生物量丰度，改变和未改变的玄武岩之间没有明显的趋势。HVNP 喷气孔沉积物（活性和残留的喷气孔相关样品）通常具有一致可检测的生物量，尽管温度似乎在丰度中发挥作用，最高温带喷气孔表现出最低的 PLFA 浓度。PLFA 剖面通常具有高比例的 brPLFA（包括铁和硫还原细菌的生物标志物），并表明玄武岩以异养生物为主，然而，没有确定社区生物标志物组成与改变类型或程度之间的明确趋势。陆地玄武岩中微生物生物量的异质性表明，识别与高生物量（生物标志物）明显相关的不同蚀变特征具有挑战性，但蚀变材料（同位体和二次风化）和喷气沉积物可能是有前途的天体生物学目标。