This study investigates how plant species and root exudates influence the structure of soil bacterial communities. Using stable isotope probing (SIP), researchers analyzed bacterial communities in the rhizosphere of four plant species—wheat, maize, rape, and barrel clover—grown in the same soil under 13C-labeled conditions. DNA from rhizosphere soil was fractionated by isopycnic centrifugation, and bacterial communities assimilating root exudates or soil organic matter (SOM) were identified through denaturing gradient gel electrophoresis (DGGE) analysis of 13C- and 12C-labeled DNA. The results showed that plant species significantly shaped the bacterial community structure in the rhizosphere. Bacteria related to Sphingobacteriales and Myxococcus assimilated root exudates in all four plants, while Sphingomonadales used both carbon sources and were found in all compartments. Sphingomonadales were specific to monocotyledons, whereas bacteria related to Enterobacter and Rhizobiales colonized all compartments and used both fresh and ancient carbon. Root exudates also indirectly influenced SOM assimilation by stimulating diverse bacterial communities. The study highlights the role of root exudates in selecting specific bacterial species and their impact on soil microbial communities. It also demonstrates the importance of plant species in shaping the rhizosphere bacterial community structure and the functional diversity of soil microbial communities. The findings emphasize the indirect impact of root exudates on SOM turnover and the role of plants in promoting microbial activities that benefit plant growth. The study provides insights into the complex interactions between plants and soil microorganisms, and the importance of understanding these interactions for sustainable agriculture and ecosystem management.This study investigates how plant species and root exudates influence the structure of soil bacterial communities. Using stable isotope probing (SIP), researchers analyzed bacterial communities in the rhizosphere of four plant species—wheat, maize, rape, and barrel clover—grown in the same soil under 13C-labeled conditions. DNA from rhizosphere soil was fractionated by isopycnic centrifugation, and bacterial communities assimilating root exudates or soil organic matter (SOM) were identified through denaturing gradient gel electrophoresis (DGGE) analysis of 13C- and 12C-labeled DNA. The results showed that plant species significantly shaped the bacterial community structure in the rhizosphere. Bacteria related to Sphingobacteriales and Myxococcus assimilated root exudates in all four plants, while Sphingomonadales used both carbon sources and were found in all compartments. Sphingomonadales were specific to monocotyledons, whereas bacteria related to Enterobacter and Rhizobiales colonized all compartments and used both fresh and ancient carbon. Root exudates also indirectly influenced SOM assimilation by stimulating diverse bacterial communities. The study highlights the role of root exudates in selecting specific bacterial species and their impact on soil microbial communities. It also demonstrates the importance of plant species in shaping the rhizosphere bacterial community structure and the functional diversity of soil microbial communities. The findings emphasize the indirect impact of root exudates on SOM turnover and the role of plants in promoting microbial activities that benefit plant growth. The study provides insights into the complex interactions between plants and soil microorganisms, and the importance of understanding these interactions for sustainable agriculture and ecosystem management.