Effect of glucose on the soil bacterial diversity and function in the rhizosphere of Cerasus sachalinensis

Most cherry orchards in China have low organic carbon content, though carbon is very important for plant growth. The changes in soil carbon and bacterial diversity were determined after different amounts of C-12-glucose were added to the rhizosphere of Cerasus sachalinensis. Soil bacteria diversity was measured using high throughput sequencing, and bacteria containing C-13-glucose were identified using DNA-SIP methods. The results demonstrated that soil microbial biomass carbon (MBC) content and the soil respiratory rate were increased at 3 and 7 days after adding glucose. The soil organic carbon (SOC) content was decreased on the 7th day in the treatment where the added glucose-C was equivalent to the MBC content. SOC content was decreased on the 15th day after adding glucose-C equivalent to five times that of the soil MBC. Compared to the controls, the relative abundance of taxa at the phylum level displayed no significant change in the treatments with glucose-C added as 10% and equal amount of soil MBC 3-30 days after treatment. However, the relative abundance of Proteobacteria increased significantly in the treatment with the addition of glucose-C equivalent to five times of soil MBC. The main changes were observed in the bacteria in several genera including A4 , Flavisolibacter, Aquicella, and Candidatus Solibacter. DNA-SIP results indicated that the relative abundance of the Proteobacteria and Pseudomonas was the highest; these were the primary bacteria phylum and genus, respectively, from day 3 to day 15. In conclusion, the changing pattern demonstrated that with the addition of more glucose, the range of the bacterial communities changed more. Proteobacteria and Pseudomonas may be the bacteria promoting priming effect.