Soil bacterial diversity, structure, and function of Suaeda salsa in rhizosphere and non-rhizosphere soils in various habitats in the Yellow River Delta, China

Soil microorganisms play a key role in regulating the biogeochemical cycles of ecosystems. However, studies that quantitatively examine bacterial metabolic groups to predict the environmental and biological impacts are limited. In this research, we employed 16S rRNA gene sequencing on an Illumina MiSeq platform to analyze bacterial diversity, structure, function, and driving factors of Suaeda salsa in rhizosphere and non-rhizosphere soils in intertidal and supratidal habitats in the Yellow River Delta, China. Results showed that bacterial richness and Shannon diversity index of the rhizosphere soil were greater in the intertidal than in the supratidal habitat. Although the bacteria of the two habitats changed extremely in community structure, the bacterial groups related to carbohydrate metabolism (CM) and amino acid metabolism (AAM) had higher abundance than the other groups in both habitats. Furthermore, they were higher in the supratidal than the intertidal habitats, and bacterial groups associated with energy metabolism (EM) are opposite. Furthermore, bacterial diversity showed no significant difference between the rhizosphere and non-rhizosphere soils. In the intertidal habitat, the rhizosphere soil had higher EM but lower AAM and CM than the non-rhizosphere soil, which indicated that bacterial structure and function were obviously influenced by the root exudates of S. salsa under flooding and salt stresses. Redundancy analysis showed that the dominant phyla were significantly affected by available phosphorus (51.0%), total potassium (32.2%), moisture content (28.1%), available potassium (25.3%), electrical conductivity (24.2%), total nitrogen (22.8%), total carbon (21.9%), and soil organic matter (21.0%). Overall, the findings provide important insights into the roles of bacterial groups in coastal wetland under climate changes.