How sediment bacterial community shifts along the urban river located in mining city

Bacterial communities play critical roles in biogeochemical cycles and serve as sensitive indicators of environmental fluctuation. However, the influence of mineral resource exploitation on shaping the bacterial communities in the urban river is still ambiguous. In this study, high-throughput sequencing was used to determine the spatial distribution of the sediment bacterial communities along an urban river in the famous mining city Panzhihua of China. The results showed that mineral resource exploitation had a significant impact on the urban river bacterial community structure but not on the bacterial ecological functions. Distinct families of bacteria often associated with nutrients (i.e., Comamonadaceae and Sphingomonadaceae) and metal contaminants (i.e., Rhodobacteraceae) were more predominant in the residential and mining area, respectively. Relative to dispersal dynamics, environmentally induced species sorting may primarily influence bacterial community structure. Heavy metals and sediment physicochemical properties had both similar and significant influence on shaping bacterial community structure. Among heavy metals, essential metal elements explained more rates of bacterial variation than toxic metals at moderate contaminant levels. Moreover, the bacteria with multiple metal resistances identified in culture-dependent experiments were probably not suitable for indicating heavy metal contamination in field research. Thus, several sensitive bacterial genera such as Rhodobacter, Hylemonella, and Dechloromonas were identified as potential bioindicators to monitor metals (iron and titanium) and nutrients (phosphorus and organic carbon) in the river ecosystem of the Panzhihua region. Together, these results profiled the coupling effect of urbanization and mineral resource utilization on shaping sediment bacterial communities in urban rivers.