Spatial and temporal variation in microbial community stability and interactions in the LUBWT

The long-distance underground box culvert water transport system (LUBWT) is an essential link between the drinking water source and the consumer. It must ensure that the water quality does not change during the transmission process. However, uncontrollable microbial growth can occur in the water delivery system during the long delivery process, leading to health and safety issues. Therefore, we applied 16s and 18s gene sequence analysis to study microbial communities in box culvert waters sampled in 2021, as well as a molecular ecological network-based approach to decipher microbial interactions and stability. Our results suggested that micro-eukaryotes in LUBWT have complex interactions such as predation, parasitism, and symbiosis compared to natural freshwater ecosystems due to their semi-enclosed box culvert environment. Total nitrogen may be the main factor affecting bacterial community interactions in addition to temperature. And using stability indicators such as robustness and vulnerability, we also found that microbial stability varied greatly from season to season, with the higher stability of microbial communities in summer. Not only that, but the stability of the micronuclei also varied greatly during water transport, which might also be related to the complex interactions among the micro-eukaryotes. In summary, our study reveals the microbial interactions and stability in LUBWT, which provides essential ecological knowledge to ensure the water quality safety of LUBWT.