Preparation of a Bacterial Consortium for Straw Degradation and Optimization of Conditions for Its Return to the Field

The yield of corn straw is huge, and returning straw to the field is an efficient utilization measure. The challenge in this approach is how to efficiently degrade the straw returned to the field. The study of efficient straw-degrading bacteria and their application conditions is an important approach. Therefore, after enrichment, separation, screening, and strain identification, three strains (X−2, X−4, and X−6) of highly efficient cellulose-degrading bacteria were obtained, namely Pseudomonas aeruginosa PA14, Brevibacillus parabrevis M3, and Bacillus cereus PgBE247. Based on antagonistic experiment results in which the strains were observed to not be antagonistic to each other, they were combined to prepare a bacterial consortium (M−1) for straw degradation. The CMCase, FPA, and β-Gase of the M−1 consortium were 28.46 U/mL, 30.93 U/mL, and 27.94 U/mL, respectively, higher than the values for single bacteria. On the 35th day, the degradation rate of corn straw by M−1 reached 79.81% in liquid medium, significantly increased by 72.06% (p < 0.01) compared to the sterile control (CK), and was significantly higher than single bacteria (p < 0.05). The straw degradation rate of M−1 was the highest at 69.69% in the simulated straw return, significantly increased by 59.84% compared to CK (p < 0.05), and increased by 18.32%, 11.59%, and 14.92% compared to the straw degradation rates of X−2, X−4, and X−6, respectively. The response surface condition optimization verification results showed that the straw degradation rate was 72.15 ± 1.21% when the amount of bacterial suspension was 25%, corn straw dosage was 9 g, initial pH was 7, and reaction temperature was 30 °C. Overall, this study revealed a new bacterial consortium for corn straw decomposition and optimized the conditions for its return to the field, providing a theoretical basis for subsequent studies.