Molecular understanding of autotrophic CO₂-fixing bacterial communities in composting based on RuBisCO genes analysis

The CO₂ fixation by autotrophic microbes has an important significance for improving carbon sequestration in composting. In this work, the succession of autotrophic CO₂-fixing bacterial communities was investigated using quantitative PCR and high-throughput sequencing of the ribulose-1,5-bisphosphate carboxylase/oxygenase genes (cbbL and cbbM). The results presented that the number of autotrophic CO₂-fixing bacteria was comparable to that in the soil, and most species have not been classified into known bacterial groups, only part of them was assigned into Proteobacteria and Actinobacteria. Phylogenetic analysis displayed that the dominant known cbbL-containing bacteria were Allochromatium vinosum, Rhodobacter sphaeroides, Nitrobacter winogradskyi, Paracoccus yeei and Porphyrobacter sp. CACIAM 03H1, while the dominant known cbbM-containing bacteria were Sulfuritalea hydrogenivorans, Pseudomonas resinovorans, Achromobacter xylosoxidans, Sphingopyxis macrogoltabida and Thermomonospora curvata. In addition, canonical correspondence analysis showed that the evolution of autotrophic CO₂-fixing bacterial communities was greatly affected by physico-chemical parameters such as temperature, C/N and pH.