Desert surface soils devoid of plant cover are populated by a variety of microorganisms, many with yet unresolved physiologies and lifestyles. Nevertheless, a common feature vital for these microorganisms inhabiting arid soils is their ability to survive long drought periods and reactivate rapidly in rare incidents of rain. Chemolithotrophic processes such as oxidation of atmospheric hydrogen and carbon monoxide are suggested to be a widespread energy source to support dormancy and resuscitation in desert soil microorganisms. Here, we assessed the distribution of chemolithotrophic, phototrophic, and desiccation-related metabolic potential among microbial populations in arid biological soil crusts (BSCs) from the Negev Desert, Israel, via population-resolved metagenomic analysis. While the potential to utilize light and atmospheric hydrogen as additional energy sources was widespread, carbon monoxide oxidation was less common than expected. The ability to utilize continuously available energy sources might decrease the dependency of mixotrophic populations on organic storage compounds and carbon provided by the BSC-founding cyanobacteria. Several populations from five different phyla besides the cyanobacteria encoded CO₂ fixation potential, indicating further potential independence from photoautotrophs. However, we also found population genomes with a strictly heterotrophic genetic repertoire. The highly abundant Rubrobacteraceae (Actinobacteriota) genomes showed particular specialization for this extreme habitat, different from their closest cultured relatives. Besides the ability to use light and hydrogen as energy sources, they encoded extensive O₂ stress protection and unique DNA repair potential. The uncovered differences in metabolic potential between individual, co-occurring microbial populations enable predictions of their ecological niches and generation of hypotheses on the dynamics and interactions among them.

中文翻译：

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干旱生物土壤结皮群落中微生物基因组的混合营养和干燥生存机制的分布

缺乏植物覆盖的沙漠表层土壤中充满了多种微生物，其中许多尚未解决生理和生活方式问题。然而，对于这些居住在干旱土壤中的微生物而言，至关重要的一个共同特征是它们能够在干旱时期生存并在罕见的降雨事件中迅速恢复活力。有人建议说，化石营养化过程（例如大气中氢和一氧化碳的氧化）是一种广泛的能源，可支持沙漠土壤微生物的休眠和复苏。在这里，我们通过种群分辨宏基因组分析，评估了以色列内盖夫沙漠的干旱生物土壤地壳（BSC）中微生物种群之间的化学营养，光养和干燥相关的代谢潜力的分布。尽管利用光和大气中的氢气作为附加能源的潜力已广泛存在，但一氧化碳的氧化却不如预期的普遍。利用连续可用能源的能力可能会减少混合营养种群对建立BSC的蓝细菌所提供的有机存储化合物和碳的依赖性。除蓝细菌编码的CO之外，还有来自五个不同门的几个种群_2个固定潜能，表明进一步潜在的独立于光合自养生物。但是，我们还发现了具有严格异养遗传谱系的种群基因组。高度丰富的红杆菌科（Actinobacteriota）基因组显示了这种极端生境的特殊化，与其最亲近的亲戚不同。除了能够利用光和氢作为能源之外，它们还具有广泛的O ₂应力保护和独特的DNA修复潜力。共同存在的单个微生物种群之间未发现的代谢潜力差异，可以预测其生态位，并就它们之间的动力学和相互作用提出假设。