In Mars-analogous hyperarid soils of the Atacama Desert, phospholipid fatty acids (PLFAs) as the main component of biomembrane play a role in reliably determining viable microbes. PLFA analyses illustrated a rise of the microbial abundance (from 5.0 × 106 to 4.2 × 107 cells g−1) and biodiversity (from 7 to 15 different individual PLFAs) from the north hyperarid core of the Atacama Desert to the southern arid region. Abundant cyclopropyl PLFAs (47.2 ± 4.6%) suggested the resistance to oligotrophic and hypersaline environments by Atacama microbial communities. The southernmost arid site had the highest proportion (8.7%) of eukaryotic and fungal lipid biomarkers. Different precipitations (ranging from 0.7 to 2 mm year−1) in the hyperarid core exerted different effects on microbial biomass, PLFA diversity, bacteria and microeukaryotes. By principal component analysis (cumulative 74.6% of variance), the dominance of PLFA hydroxylation was associated with the microbial viability; bacteria rich in C16:0, C18:0 and C16:1ω9 favoured higher soil conductivity and nitrate; and other PLFAs contributed more to the organic content. Additionally by comparing the ratios of PLFAs to well-preserved organics (e.g., mineral-bound organic carbon and microbial phosphorus), I found that the degradation of PLFAs decreased to a minimum when the mean annual precipitation is lower than 2 mm. These findings may further specify identifiable biomarkers on Mars, if potentially extant Martian microbes possess comparable phospholipid membrane structure.

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阿塔卡马沙漠类似火星的土壤中的磷脂生物标志物

在阿塔卡马沙漠的类似火星的超干旱土壤中，作为生物膜主要成分的磷脂脂肪酸 (PLFA) 在可靠地确定活微生物方面发挥着重要作用。PLFA 分析表明微生物丰度上升（从 5.0 × 106至 4.2 × 107细胞 g-1) 和从阿塔卡马沙漠北部超干旱核心到南部干旱地区的生物多样性（从 7 到 15 个不同的个体 PLFA）。丰富的环丙基 PLFA (47.2 ± 4.6%) 表明 Atacama 微生物群落对贫营养和高盐环境具有抗性。最南端的干旱地区真核和真菌脂质生物标志物的比例最高（8.7%）。不同的降水量（范围从 0.7 到 2 毫米年-1) 在超干旱核心对微生物量、PLFA 多样性、细菌和微真核生物产生不同的影响。通过主成分分析（累积方差74.6%），PLFA羟基化的优势与微生物活力有关；富含 C16:0、C18:0 和 C16:1 的细菌ω9 有利于较高的土壤电导率和硝酸盐；和其他 PLFA 对有机含量的贡献更大。此外，通过比较 PLFAs 与保存完好的有机物（例如，矿物结合的有机碳和微生物磷）的比例，我发现当年平均降水量低于 2 mm 时，PLFAs 的降解降至最低。如果可能现存的火星微生物具有类似的磷脂膜结构，这些发现可能会进一步确定火星上可识别的生物标志物。