It is believed that climate change will influence most of interactions that sustain life on Earth. Among these, the recruitment exerted by plants in their roots vicinity can change, leading to differential assemblages of microbiomes in the rhizosphere. We approached this issue analyzing the variations in the composition of bacterial communities in the rhizosphere of sugarcane cultivated under two concentrations of atmospheric CO 2 (350 or 700 ppm). In addition to the analysis of bacterial community, the use of DNA-SIP allowed the comparison of bacterial groups assimilating roots exudates (based on 13 C-labeled DNA) in both conditions, in a period of 8 days after the CO 2 pulse. The separation of 13 C-DNA indicated the low but increasing frequency of labeling in the rhizosphere, as averages of 0.6, 2.4 and 5.0% of total DNA was labeled after 2, 4 and 8 days after the 13 CO 2 pulse, respectively. Based on large-scale sequencing of the V6 region in the gene 16S rRNA, we found an increase in the bacterial diversity in the 13 C-DNA along the sampling period. We also describe the occurrence of distinct bacterial groups assimilating roots exudates from sugarcane cultivated under each CO 2 concentration. Bacilli, Gammaproteobacteria and Clostridia showed high affinity for the C-sources released by sugarcane under 350 ppm of CO 2 , while under elevated concentration of CO 2 , the assimilation of roots exudates was prevalently made by members of Bacilli and Betaproteobacteria. The communities became more similar along time (4 and 8 days after CO 2 pulse), in both concentrations of CO 2 , electing Actinobacteria, Sphingobacteriia and Alphaproteobacteria as the major cross-feeders on sugarcane exudates. In summary, we described the bacterial groups with higher affinity to assimilate roots exudates in the rhizosphere of sugarcane, and also demonstrated that the rhizosphere community can be differentially assembled in a future scenario with increased contents of CO 2 . This article is protected by copyright. All rights reserved.
Energy, Environment Protection, Nuclear Power Engineering