Restoration via the aggregate spray-seeding technique affected the soil proteobacteria on an Uninhabited Island: Community structure, metabolic function, nutritional type, and life strategy

Abstract

This study aimed to explore the impact of aggregate spray-seeding (ASS) restoration measures on the soil proteobacterial community. Using environmental DNA sequencing, we analyzed the proteobacterial communities in the soils of 3 natural vegetation (NV) plots, 3 traditional afforestation (TA) plots, and 12 spray-seeding restoration (SR) plots located on Triangle Island in Zhuhai city, China, during both the summer and winter seasons. We estimated the metabolic function, nutritional type, and life strategy of Proteobacteria through the FAPROTAX and rrnDB databases. Our findings demonstrated that Proteobacteria was the predominant phylum (relative abundance = 40.1–48.4%) in the soil bacterial communities across all three treatments. The relative abundance of Alphaproteobacteria ranged from 28.5% to 38.1%, which was significantly greater (2.6–10.3 times, p < 0.05) than that of Betaproteobacteria or Gammaproteobacteria. Most (90%) proteobacterial genera and all rhizobial genera found in the NV and TA soils were also present in the SR soil, but there were distinct differences in the proteobacterial community structures between the SR soil and NV/TA soil. Across all seasons and treatments, the proteobacterial communities were related to functions such as ureolysis, nitrogen fixation, nitrate reduction, and hydrocarbon degradation. The relative abundance of Proteobacteria associated with chitinolysis was greater in the SR soil than in the NV and TA soils. Among the overall proteobacterial community, the chemoheterotrophic, chemoautotrophic, and phototrophic bacteria accounted for 65–77%, 19–31%, and less than 5%, respectively. Alphaproteobacteria tended to be K strategic, while Betaproteobacteria and Gammaproteobacteria tended to be r strategic. The soil pH, organic carbon content, and nitrogen content were significantly correlated with the metabolic function and nutritional type of the soil Proteobacteria according to the Mantel test results. In conclusion, the application of the ASS technique can effectively restore the biodiversity, metabolic function, and nutritional-type structure of the soil proteobacterial community. Additionally, this study highlights that certain metabolic functions of the proteobacterial community in SR soil undergo changes in response to the use of certain restoration materials. These findings suggest that the targeted addition of specific repair materials can modulate soil microorganism functionality and provide a valuable theoretical foundation for ecological restoration engineering practices.