Effects of single and synthetic microbial community inoculants on the rhizosphere soil and root microbiomes of rice (Oryza sativa)

This study compared the effects of a single-strain microbial inoculant, Brevundimonas diminuta NH1, and a synthetic microbial community (FSQN) composed of Bacillus amyloliquefaciens FH1, Ochrobactrum tritici S112, Gluconacetobacter liquefaciens QZR14, and B. diminuta NH1 on the rhizosphere soil and root microbiomes of rice (Oryza sativa) to investigate how these inoculation strategies differ in microbiome regulation and growth promotion. High-throughput sequencing was used to assess microbial α- and β-diversity, community composition, predicted bacterial and fungal functions, and correlations between microbiome shifts and rice growth traits. We found that neither inoculant significantly affected microbial α-diversity, but both significantly altered β-diversity in rhizosphere soil and roots. Compared with the control, the single-strain treatment mainly enriched Mortierella, Glaciozyma, and Bovista in rhizosphere soil, and Clostridium sensu stricto, Cronobacter, Exiguobacterium, Kosakonia, and Pseudomonas in roots. The synthetic community mainly enriched Mortierella, Tausonia, Fusarium, and Glomerella in rhizosphere soil, and Exiguobacterium, Pseudomonas, and Rhodotorula in roots. Functional prediction indicated that the single-strain inoculant enhanced sulfur respiration, ureolysis, xylanolysis, and denitrification-related functions, whereas the synthetic community enhanced ectomycorrhizal, endomycorrhizal, and plant-saprotrophic functions. Shoot height and dry weight were may positively associated with enriched taxa and functions, particularly Mortierella, Exiguobacterium, and endophytic functions.