Department of Food, Environmental and Nutritional Sciences, University of Milan, Via Celoria 2, Milan, Italy.
Department of Science and High Technology, University of Insubria, Via Valleggio 11, Como, Italy.
Microbiol Res. 2022 Oct;263:127144. doi: 10.1016/j.micres.2022.127144. Epub 2022 Jul 26.
Studies about biodegradation potential in soils often refer to artificially contaminated and simplified systems, overlooking the complexity associated with contaminated sites in a real context. This work aims to provide a holistic view on microbiome assembly and functional diversity in the model site SIN Brescia-Caffaro (Italy), characterized by historical and uneven contamination by organic and inorganic compounds. Here, physical and chemical analyses and microbiota characterization were applied on one-hundred-twenty-seven soil samples to unravel the environmental factors driving bacterial community assembly and biodegradation potential in three former agricultural fields. Chemical analyses showed a patchy distribution of metals, metalloids and polychlorinated biphenyls (PCB) and allowed soil categorization according to depth and area of collections. Likewise, the bacterial community structure, described by molecular fingerprinting and 16S rRNA gene analyses, was significantly different according to collection site and depth. Pollutant concentrations (i.e., hexachloro-biphenyls, arsenic and mercury), nitrogen content and parameters related to soil texture were identified as main drivers of microbiota assembly, being significantly correlated to bacterial community composition. Moreover, bacteria putatively involved in the aerobic degradation of PCBs were enriched over the total bacterial community in topsoils, where the highest activity was recorded using fluorescein hydrolysis as proxy. Metataxonomic analyses revealed the presence of bacteria having metabolic pathways related to PCB degradation and tolerance to heavy metals and metalloids in the topsoil samples collected in all areas. Overall, the provided dissection of soil microbiota structure and its degradation potential in the SIN Brescia-Caffaro can contribute to target specific areas for rhizoremediation implementation. Metagenomics studies could be implemented in the future to understand if specific degradative pathways are present in historically polluted sites characterized by the co-occurrence of multiple classes of contaminants.
关于土壤生物降解潜力的研究通常涉及人为污染和简化的系统，而忽略了实际污染场地的复杂性。本工作旨在为意大利布雷西亚-卡法罗（Brescia-Caffaro）模型场地的微生物组组装和功能多样性提供一个整体视角，该场地历史上受到有机和无机化合物的不均匀污染。在这里，对 127 个土壤样本进行了物理化学分析和微生物群落特征分析，以揭示三个前农业领域中驱动细菌群落组装和生物降解潜力的环境因素。化学分析显示金属、类金属和多氯联苯（PCB）的分布不均匀，并根据采集深度和区域对土壤进行了分类。同样，通过分子指纹图谱和 16S rRNA 基因分析描述的细菌群落结构也根据采集地点和深度而有显著差异。污染物浓度（如六氯联苯、砷和汞）、氮含量以及与土壤质地相关的参数被确定为微生物群落组装的主要驱动因素，与细菌群落组成显著相关。此外，在表层土壤中，有氧降解 PCB 的细菌数量相对于总细菌群落增加，使用荧光素水解作为替代物记录到最高的活性。分类群分析表明，在所有地区采集的表层土壤样本中存在与 PCB 降解和重金属及类金属耐受相关的代谢途径的细菌。总的来说，提供的布雷西亚-卡法罗污染场地土壤微生物群落结构及其降解潜力的剖析有助于针对根际修复实施的特定区域。未来可以进行宏基因组学研究，以了解在具有多种污染物共存的历史污染场地中是否存在特定的降解途径。
