High biodiversity and distinct assembly patterns of microbial communities in groundwater compared with surface water

The differences in bacterial community assembly mechanism between surface water and groundwater, as well as the driving factors of environmental factors, are still unknown. Here we aimed to answer these questions by analyzing microbial community samples from surface water and groundwater. We observed a strong connection between microbial communities in surface water and groundwater and several human pathogens are shared between surface water and groundwater; however, the richness and diversity of groundwater microbial communities were greater than those of surface water, regardless of the season. Additionally, bacterial community compositions of surface water and groundwater differed significantly between seasons. Most importantly, the groundwater community exhibited a highly deterministic assembly process (56% contributed by deterministic process, with neutral community model R² = 0.277) compared with surface water (51% contributed by deterministic process, with R² = 0.526). This study provides a deep understanding of the effects of environmental factors on surface water and groundwater microbial communities, to better protect water resources.