Influence of functionalized graphene on the bacterial and fungal diversity of Vicia faba rhizosphere soil

The effect of functionalized graphene on the growth and development of Vicia faba L. was investigated by analyzing its impact on the composition and diversity of the microbial community in rhizosphere peat soil. Seedlings of V. faba planted in this peat soil were treated with either distilled water (CK) or 25 mg·L⁻¹ (G25) of functionalized graphene solution. Results showed that the height and root length of V. faba seedlings in the G25 group were significantly larger than those in CK group. The microbial community was analyzed by amplifying and sequencing the 16S rRNA gene V3–V4 region of bacteria and internal transcribed spacer region of fungi in rhizosphere soil using Illumina MiSeq technology. Alpha and beta diversity analysis indicated that functionalized graphene increased the richness and diversity of bacteria and fungi in the V. faba rhizosphere peat soil. The abundances of three nitrogen cycling-related bacteria, Hydrogenophaga, Sphingomonas and Nitrosomonadaceae, were also altered after treatment with the functionalized graphene. The relative abundance of Basilicum, related to soil phosphorus solubilization, decreased in the fungal community, while the relative abundance of Clonostachys and Dimorphospora, which exhibited strong biological control over numerous fungal plant pathogens, nematodes and insects, increased in the soil after functionalized graphene treatment. Redundancy analysis revealed that the potential of hydrogen (pH), organic matter, and total phosphorus contributed the most to the changes in bacterial and fungal community composition in the rhizosphere soil. Overall, our findings suggested that the addition of functionalized graphene altered the relative abundances of nitrogen and phosphorus cycling-related microorganisms in peat soil, promoting changes in the physicochemical properties of the soil and ultimately leading to the improved growth of V. faba plants.