Abstract Salinization is a matter of growing concern as it decreases plant productivity in degraded grassland soils; however, its effects on bacterial and fungal communities remain unknown. Therefore, we used the next-generation sequencing technology of soil bacterial 16S rRNA and fungal internal transcribed spacer (ITS) to investigate the diversities and structures of soil bacterial and fungal communities under four different salinity or electrical conductivity (EC) conditions. Our results showed that high salinity increased the relative abundance of Gemmatimonadetes and Bacteroidetes, but, decreased that of Proteobacteria and Firmicutes. In addition, high soil salinity increased the relative abundance of the fungal phylum Ascomycota. The soil pH value significantly increased as the soil salinity increased. Structural equation models (SEMs) showed that soil pH and EC had a total impact on the soil total microbial diversity and basic respiration. Increasing soil pH directly decreased the soil total Shannon diversity and basic respiration according to the SEMs. In contrast, increasing the soil EC directly increased soil total Shannon diversity and decreased soil basic respiration. Soil pH was negatively correlated with both bacterial and fungal diversity compared with soil EC in the SEMs. Our results indicate the opposite effects between soil bacterial and fungal diversity on soil microbial respiration in the highly saline grassland soils.

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评估土壤盐渍化对培养条件下土壤微生物呼吸和多样性的影响

摘要 盐渍化是一个日益受到关注的问题，因为它会降低退化草地土壤中的植物生产力；然而，它对细菌和真菌群落的影响仍然未知。因此，我们利用土壤细菌 16S rRNA 和真菌内部转录间隔区 (ITS) 的新一代测序技术，研究了四种不同盐度或电导率 (EC) 条件下土壤细菌和真菌群落的多样性和结构。我们的结果表明，高盐度增加了 Gemmatimonadetes 和 Bacteroidetes 的相对丰度，但降低了 Proteobacteria 和 Firmicutes 的相对丰度。此外，高土壤盐度增加了真菌门子囊菌的相对丰度。随着土壤盐分的增加，土壤pH值显着升高。结构方程模型 (SEM) 表明，土壤 pH 值和 EC 对土壤总微生物多样性和基本呼吸有总体影响。根据扫描电镜，增加土壤 pH 值直接降低土壤总香农多样性和基本呼吸。相反，增加土壤 EC 直接增加了土壤总香农多样性并降低了土壤基本呼吸。与 SEM 中的土壤 EC 相比，土壤 pH 值与细菌和真菌多样性均呈负相关。我们的结果表明土壤细菌和真菌多样性对高盐度草地土壤中土壤微生物呼吸的影响相反。相比之下，增加土壤 EC 直接增加了土壤总香农多样性并降低了土壤基本呼吸。与 SEM 中的土壤 EC 相比，土壤 pH 值与细菌和真菌多样性均呈负相关。我们的结果表明土壤细菌和真菌多样性对高盐度草地土壤中土壤微生物呼吸的影响相反。相反，增加土壤 EC 直接增加了土壤总香农多样性并降低了土壤基本呼吸。与 SEM 中的土壤 EC 相比，土壤 pH 值与细菌和真菌多样性均呈负相关。我们的结果表明土壤细菌和真菌多样性对高盐度草地土壤中土壤微生物呼吸的影响相反。