Advancing towards sustainable cities needs a better understanding of all components of urban ecosystems, including soils, but the biological component of urban soils remains poorly studied compared to natural and agricultural soils. With the objective of advancing knowledge in this aspect, we studied the microbiological properties in 61 soils of the city of Santiago de Compostela (NW Spain), under several land uses (urban grassland, urban forest, urban garden, and periurban arable land). We determined thirteen extracellular enzymatic activities as a proxy of microbial community functioning, along with measures of microbial activity (basal respiration), microbial abundance (DNA extraction and real-time PCR), and the composition of microbial communities (Illumina MiSeq sequencing on 16S rRNA and ITS marker regions). Results showed a high variability in all of the microbiological variables among soils, reflecting the typical spatial heterogeneity of urban soils. Respiration and enzymatic activities were highly correlated to soil organic matter contents but not affected by land use within the city, with the exception of alkaline phosphomonoesterase activity, which was higher in urban garden soils and correlated positively to pH and availability of phosphorus and nitrogen. Unlike fungal abundance, we recorded a higher bacterial abundance in the urban grasslands than in the other land uses. While the composition of bacterial communities was structured in a more homogeneous, land use-dependent manner (33% variance, p_Adonis = 0.001), the respective fungal communities were more heterogeneous and less influenced by group-dependent characteristics (18%, p_Adonis = 0.001). Soil pH had a larger influence on the bacterial community composition (28% variance) compared to the fungal composition (8.5% variance). Overall, these findings provide evidence that the typically high soil heterogeneity of urban ecosystems is the main driving force for the urban soil microbiome, with soil organic matter determining largely microbial activity.

迈向可持续城市需要更好地了解城市生态系统的所有组成部分，包括土壤，但与自然和农业土壤相比，城市土壤的生物成分仍然缺乏研究。为了推进这方面的知识，我们研究了圣地亚哥德孔波斯特拉市（西班牙西北部）的 61 种土壤中的微生物特性，在几种土地用途（城市草地、城市森林、城市花园和城郊耕地）下。我们确定了 13 种细胞外酶活性作为微生物群落功能的代表，以及微生物活性（基础呼吸）、微生物丰度（DNA 提取和实时 PCR）和微生物群落组成（Illumina MiSeq 16S rRNA 测序和 ITS 标记区域）。结果表明，土壤中所有微生物变量的变异性很高，反映了城市土壤的典型空间异质性。呼吸和酶活性与土壤有机质含量高度相关，但不受城市土地利用的影响，但碱性磷酸单酯酶活性除外，其在城市花园土壤中较高，与 pH 值和磷和氮的有效性呈正相关。与真菌丰度不同，我们记录到城市草地中的细菌丰度高于其他土地利用。虽然细菌群落的组成以更均匀、依赖土地利用的方式构成（33% 的方差，p 呼吸和酶活性与土壤有机质含量高度相关，但不受城市土地利用的影响，但碱性磷酸单酯酶活性除外，其在城市花园土壤中较高，与 pH 值和磷和氮的有效性呈正相关。与真菌丰度不同，我们记录到城市草地中的细菌丰度高于其他土地利用。虽然细菌群落的组成以更均匀、依赖土地利用的方式构成（33% 的方差，p 呼吸和酶活性与土壤有机质含量高度相关，但不受城市土地利用的影响，但碱性磷酸单酯酶活性除外，其在城市花园土壤中较高，与 pH 值和磷和氮的有效性呈正相关。与真菌丰度不同，我们记录到城市草地中的细菌丰度高于其他土地利用。虽然细菌群落的组成以更均匀、依赖土地利用的方式构成（33% 的方差，p 与真菌丰度不同，我们记录到城市草地中的细菌丰度高于其他土地利用。虽然细菌群落的组成以更均匀、依赖土地利用的方式构成（33% 的方差，p 与真菌丰度不同，我们记录到城市草地中的细菌丰度高于其他土地利用。虽然细菌群落的组成以更均匀、依赖土地利用的方式构成（33% 的方差，p_Adonis  = 0.001），各自的真菌群落更加异质，受群体依赖性特征的影响较小（18％，p _Adonis  = 0.001）。与真菌组成（8.5% 方差）相比，土壤 pH 值对细菌群落组成（28% 方差）的影响更大。总体而言，这些发现提供了证据，表明城市生态系统典型的高土壤异质性是城市土壤微生物组的主要驱动力，土壤有机质在很大程度上决定了微生物活动。