Soil bacterial community composition but not alpha diversity altered along gradient of Spartina alterniflora invasion on a coast of Yellow Sea, China

Li Yang ¹ Yue Peng ¹ Shuang Wang ^1,2 Chenxuan Rong ¹ Huice Dong ¹ Hongshan Li ³ Baoming GE ^1*

• ¹ Yancheng Teachers University, Yancheng, China
• ² Nanjing Tech University, Nanjing, Jiangsu Province, China
• ³ Yancheng Institute of Technology, Yancheng, Jiangsu, China

Spartina alterniflora invasion may alter the characteristics and functions of the coastal wetland ecosystems. Previous studies have shown that invasion changes the biogeochemical processes and microbial diversity in marsh ecosystems, however, knowledge of the changes in bacterial communities and their function at different soil depths during invasion remains limited. In the present study, we investigated S. alterniflora invasion on the dynamic changes of soil bacterial communities using Illumina MiSeq sequencing analyses of 16S rRNA at different soil depths (i.e., 0-10, 10-20, and 20-40 cm) during the invasive process (i.e., 1-, 4-, 7-, and 12-year), as well as the potential correlations between soil physicochemical characteristics, and enzyme activities. Our results show that the invasion of S. alterniflora did not significantly affect soil bacterial alpha diversity or the functional profiles at the first and second levels of the Kyoto Encyclopedia of Genes and Genomes (KEGG). Furthermore, no significant changes were observed across different soil depths However, the relative abundances of Chloroplast and Alphaproteobacteria increased from 3.03% and 5.05% in bare mudflat to 13.61% and 8.95% in the 12-year old S. alterniflora-invaded soil, respectively, whereas those of Deltaproteobacteria, Acidimicrobiia, and Bacilli decreased after S. alterniflora invasion for approximately 12 years. The relative abundances of soil bacteria varied with soil depth. Total phosphorus, carbon-to-nitrogen ratio, total carbon, and catalase activity were the key factors affecting soil bacterial community composition. This study provides a comprehensive understanding of the dynamic changes in bacterial communities, soil physicochemical characteristics, and enzyme activities during S. alterniflora invasion on coastal wetlands.