Tidal flats Targeted loci environmental. tidal flat metagenome

Tidal flats are important components of coastal ecosystems. Bacterial communities living in tidal flat sediments can drive organic matter decomposition and biogeochemical processes in coastal ecosystems. However, their structure and function in tidal flats are poorly understood. In tidal flats located at temperate coastal regions, soil microbial communities face large seasonal variations in temperature. And successional tidal flat ecosystems form natural environmental gradients, which may influence bacterial community structure and function. The aim of this study was to reveal how the bacterial community structure and function respond to the seasonal temperature variation along a successional series of tidal flats (subtidal, intertidal and supratidal flats). Bacterial community structure and function from tidal flats were analyzed over four seasons by 16S rRNA genes and imputed metagenomes. The bacterial community structure and function were different among the successional series of tidal flats. The relative abundances of Acidobacteria, Gemmatimonadetes, and Nitrospirae increased, while Chloroflexi, Actinobacteria, and Firmicutes decreased, from subtidal to supratidal flat. The bacterial phylogenetic diversity increased, and phylogenetic turnover decreased from subtidal to supratidal flat. The differences among functional metagenomics were smaller than bacterial community structure. The core metabolic pathways appeared high similarity in tidal flats. Moreover, the bacterial community structure and function were significantly different among seasons. Temperature, and nitrite and clay contents were the main drivers of bacterial community structure and function. Together, these indicate that bacterial community structure and function in tidal flats shifted by tidal action and seasonal temperature changes, and the function were more stable than structure.