Purpose

Water availability influences soil ecosystem functioning by shaping soil microbial community composition and regulating metabolic rate. These moisture effects are mirrored in taxonomic and functional attributes of actively growing microorganisms.

Methods

Stable isotope probing (SIP) technique with ¹⁸O-H₂O as the labeling substrate was used to capture the active microbiome in a saline soil under different moisture conditions. The SIP microcosms were adjusted to 20%, 60%, or 100% of the soil water holding capacity (WHC) with ¹⁸O- or ¹⁶O-H₂O and were incubated for 4 weeks. The bacterial communities in these microcosms were examined by amplicon sequencing of 16S rRNA genes. The ¹⁸O-labeled DNA was recovered by ultracentrifugation and fractionation. Shotgun metagenomic sequencing was performed with the labeled DNA to explore the moisture effects on functional attributes of these active microbes.

Results

Isotopes (¹⁶O and ¹⁸O) had a negligible effect on soil bacterial communities compared with soil moisture. Taxonomic alignment of both total and ¹⁸O-labeled microbiomes revealed contrasting tendencies for Actinobacteria and Proteobacteria along the moisture gradient. Archaeal components became more abundant at 60% WHC and were dominated by Euryarchaeota. Functional annotation of the active microbiomes revealed broad responses in genes associated with osmotic regulation, membrane transport, cell motility, iron acquisition, phages and prophages to moisture manipulation. In particular, the considerable changes in protein biosynthesis genes suggested an altered reproductive strategy of the dominant taxa at different WHC levels.

Conclusion

These findings indicate taxonomic and functional effects of soil moisture on active prokaryotes in a saline soil, and demonstrate the potential of combined ¹⁸O-water SIP and metagenomics in achieving a holistic understanding of the active soil microbiome.

中文翻译：

---

水分对18种O信息的宏基因组学揭示的盐渍土壤中活性原核生物群落的影响

目的

水分可利用性通过影响土壤微生物群落组成和调节代谢速率来影响土壤生态系统的功能。这些水分影响反映在活跃生长的微生物的分类和功能属性中。

方法

以¹⁸ O-H ₂ O为标记底物的稳定同位素探测（SIP）技术用于在不同湿度条件下在盐渍土壤中捕获活性微生物组。用¹⁸ O-或¹⁶ O-H ₂ O将SIP微观范围调整为土壤持水量（WHC）的20％，60％或100％，并孵育4周。通过16S rRNA基因的扩增子测序检查了这些微观世界中的细菌群落。的¹⁸ O型标记的DNA通过超速离心和分馏回收。用标记的DNA进行sequencing弹枪宏基因组测序，以探讨水分对这些活性微生物功能特性的影响。

结果

与土壤水分相比，同位素（¹⁶ O和¹⁸ O）对土壤细菌群落的影响可忽略不计。总的和^18个O标记的微生物组的分类学比对揭示了放线菌和变形杆菌沿湿度梯度的趋势相反。在60％的WHC中，古细菌成分变得更加丰富，并以Euryarchaeota为主。活性微生物群的功能注释揭示了与渗透调节，膜运输，细胞运动，铁的获取，噬菌体和对水分操纵的预言有关的基因中的广泛反应。特别是，蛋白质生物合成基因的显着变化表明，在不同的WHC水平下，优势类群的繁殖策略发生了变化。

结论

这些发现表明了土壤水分对盐渍土壤中活性原核生物的分类学和功能作用，并证明了¹⁸ O-水SIP和宏基因组学相结合的潜力，可以全面了解活性土壤微生物组。