Does urbanization shape bacterial community composition in urban park soils? A case study in 16 representative Chinese cities based on the pyrosequencing method.

Although the geographical distribution patterns of microbes have been studied for years, few studies have focused on urban soils. Urbanization may have detrimental effects on the soil ecosystem through pollution discharge and changes in urban climate. It is unclear whether urbanization-related factors have any effect on soil bacterial communities. Therefore we investigated geographical patterns of soil microbial communities in parks in 16 representative Chinese cities. The microbial communities in these 95 soil samples were revealed by 454-pyrosequencing. There were 574,442 effective sequences among the total of 980,019 16S rRNA gene sequences generated, showing the diversity of the microbial communities. Proteobacteria, Actinobacteria, Acidobacteria, Planctomycetes, Chloroflexi and Bacteroidetes were found to be the six dominant phyla in all samples. Canonical correspondence analysis showed that pH, followed by annual average precipitation, annual average temperature, annual average relative humidity and city sunshine hours, Mn and Mg were the factors most highly correlated with the bacterial community variance. Urbanization did have an effect on bacterial community composition of urban park soils but it contributed less to the total variance compared with geographical locations and soil properties, which explained 6.19% and 16.78% of the variance, respectively.