Bacterial communities of sediments in a seawater-freshwater transition zone during the wet and dry seasons in Pearl River Estuary Raw sequence reads

Seawater intrusion has a detrimental effect on industrial/agricultural production and human health. One question of particular interest is how the microbial community responds to seawater intrusion with seasonal variation. The current study explored the dynamic changes in bacterial community composition and interaction in the vicinity of Pearl River Estuary in January (dry season) and September (wet seasons). The results indicated that the salinity (electrical conductivity value) of sediment samples obtained in the dry season was higher than in the wet season. The salt stress induced a declined alpha diversity and resulted in a loosely connected and unstable biotic interaction network in the bacterial communities. Random forest prediction and redundancy analysis indicated that salinity substantially affected the bacterial communities. Multiple lines of evidence, including the enrichment of bacterial taxa in the high-salinity location, microbe-microbe interactions, environment-microbe interactions, and machine learning approach, demonstrated that the families Moraxellaceae and Planococcaceae were the keystone taxa and were resistant to salt stress, which suggested that both of them can be used as potential biological indicators of monitoring and controlling seawater intrusion.