不同地区土壤古菌群落对重金属污染的响应

Response of Soil Archaeal Community to Heavy Metal Pollution in Different Typical Regions

为探讨农田土壤古菌群落结构与构建机制对不同类型重金属污染的响应特征及影响因素,采集高地质背景区、涉重金属企业和工矿区周边农田土壤样品,通过高通量测序,结合土壤理化性质,对土壤古菌群落组成及构建机制进行研究.结果表明,本研究区域内农田土壤重金属空间异质性高,镉污染较广泛,除工矿区部分土壤样本存在强生态风险,其他样本存在轻微的潜在生态风险.不同地区古菌群落结构差异较大,泉古菌门(Crenarchaeota)为优势菌门,占比62.7%~98.3%,其次为Halobacterota(1.1%~23.2%).环境因子中,土壤有机质含量、pH、砷和铅含量与古菌群落显著相关(P<0.05),是古菌群落结构差异的主要驱动因子.零模型分析表明本研究古菌群落在系统发育上聚集,确定性过程驱动古菌群落构建,有机质和pH等环境因子的异质选择作用主导古菌群落形成.因此,环境过滤的确定性作用最终驱动本研究古菌群落构建,环境异质性导致了古菌群落多样性和空间异质性,从而增强古菌抵御环境胁迫的能力,利于农田生态系统功能的稳定性和可持续性.

Soil archaeal communities play an essential role in the biogeochemical cycles of agricultural ecosystems. However,the response and mechanisms of soil archaeal community structure and assembly processes to heavy metal pollution remain poorly understood. This study examined the archaeal community composition and assembly process and their relationships with environmental factors in arable soils around high geological background areas,metal enterprises,and mining areas,based on high-throughput sequencing. The arable soils within the study area exhibited high spatial heterogeneity of heavy metal content,as well as severe cadmium pollution. The ecological risk levels were high in some soil samples from mining areas,but low to moderate in other soil samples. Crenarchaeota( 62. 7%-98. 3%) was the dominant phyla in all soil samples,followed by Halobacterota( 1. 1%-23. 2%).The pH,organic matter,arsenic,and lead contents of the soil were significantly correlated with the archaeal community( P < 0. 05),making them the main driving factors of archaeal community structure. The null-model analysis showed that the assembly process of the archaeal community was mainly influenced by heterogeneous processes,including heterogeneous selection( deterministic process) and dispersal limitation( stochastic process). Heterogeneous selection played a vital role in our study areas,while homogeneous selection only occurred in samples around the metal enterprises. Therefore,environmental selection was the ultimate driver of the archaeal community assembly process in this study,and its relative importance varied according to habitat type. Environmental heterogeneity increased the contribution of heterogeneous selection to community assembly, thus enhancing the community’s resistance to environmental stress,and contributing to the stability and sustainability of the agricultural ecosystem.