Rice Rhizosphere Metagenome in Association with Application of Biochar under Continuous Exposure to Elevated Carbon Dioxide

The objective of the present study is to analyze and compare the taxonomic composition of the microbiome in the soil of lowland paddy exposed to elevated carbon dioxide (eCO2, 550 ± 30 μmol mol–1) for a long time and amended with biochar (8 years) on an open bulk paddy soil (aCO2, 402 ± 30 μmol mol–1) (ELE and AMB, respectively). We analyzed the structural and functional changes of the microbial community structure in the paddy rhizospheric soil using Illumina Hiseq metagenomic sequencing, wherein the taxonomic analysis resulted in a significant increase of phyla with 18.7 and 12.9% increase of Proteobacteria and Actinobacteria in ELE over AMB. The sequence analysis of AMB and ELE for biological, cellular, and molecular functions showed that greater functions were attributed to ELE. The sequence analysis of KEGG revealed that the soil carbon and nitrogen metabolic pathways were actively involved on ELE rather than AMB. The entire study provided insights to understanding the response of simulated CO2 in the rhizosphere microbial community with regard to diversity and function.