Successful Formulation and Application of Low-Temperature Bacterial Agents for Corn Stover Degradation

Abstract

Solid bacterial agents are required to accelerate stover degradation in low-temperature areas. However, the laboratory-to-practice translation of bioprocessing techniques is hindered by high cost, poor practicality, and short shelf life. Using corn stover powder, starch, and bran as additives, we screened Pseudomonas putida and Acinetobacter lwoffii, which effectively degrades corn stover at low temperatures, to develop a sustainable and low-cost bacterial agent formula that ensures bacterial viability in low-temperature soil and storage. The optimal formulation included precipitates and additives at a 1:4 ratio, including corn stover powder, starch, and bran at a 4:3:9 ratio. The viable bacterial count with this formulation reached 7.5 × 1010 colony-forming units/g, with high lignocellulase activities. The degradation effect of the optimal formulation on stover and its components, in both lab soil culture simulation and the field environment, was significantly higher than that without bacterial agent application. This formulation had an outstanding effect on lignin. The optimal storage conditions included vacuum packing under 10% water content at 4 °C; the survival rate of viable bacteria reached 85.33% after 180 d. Given the global value of stover-return agriculture, our results offer a valuable strategy for application in low-temperature soils where stover degradation rates are otherwise low.