Synergistic Co-Inoculation of Bacillus velezensis and Pseudomonas helmanticensis Enhances Corn Straw Degradation via Microbial Community Restructuring and Saprotroph Dominance.

This study evaluated the potential of individual and co-inoculation with Bacillus velezensis (Bv) and Pseudomonas helmanticensis (Ph) as microbial decomposers for corn straw. The co-inoculation (BP) treatment demonstrated the highest total mass loss for cellulose, hemicellulose, and total straw, significantly outperforming the single-strain treatments (Bv and Ph) and the non-inoculated control (CK). All inoculated treatments consistently enhanced degradation over time and lowered pH compared to CK. High-throughput sequencing revealed that inoculation dramatically reshaped the soil microbial community. All treatments reduced microbial ASVs and bacterial alpha diversity (ACE, Chao1, Shannon), with the most pronounced effect observed for Bv. Beta diversity analysis showed distinct, treatment-specific clustering. Critically, FUNGuild analysis indicated a significant functional shift, with all inoculants increasing saprotroph abundance and decreasing pathotrophs. The BP consortium exhibited a synergistic effect, driving saprotroph dominance to >96%. These results demonstrate that the synergistic co-inoculation enhances straw decomposition by restructuring the microbial community towards functional dominance of saprotrophs.