Construction of a low-temperature degrading synthetic bacterial community of corn straw

The stability of the cellulose structure in straw creates a challenge for short-term degradation in the natural environment, especially in the cold regions of north China. Therefore, to secure strains that can degrade straw at low temperatures, we selected soil samples from straw-returning land and used cellulose as the only carbon source. After conducting preliminary screening and further re-screening, we ultimately selected three strains that exhibited efficient degradation of corn straw at a temperature of 4 ℃. Subsequently, the synthetic bacterial community C was constructed using these strains: Stenotrophomonas maltophilia , Flavobacterium johnsoniae and Pantoea rodasii .

We conducted a 45-day solid-state and liquid-state fermentation experiment at low-temperature (12 ℃). The activity of lignocellulase was determined, and the enzyme production conditions were optimized. The results show that the liquid fermentation degradation rate of straw increased by 40 % compared with the control group in the natural state (without adding C). Similarly, the solid-state fermentation degradation rate of straw increased by 30 %, which was significantly faster than that of the control group. Finally, the enzyme production conditions of strain C were optimized as follows: culture time 96 h, inoculation amount 4 %, temperature 12 ℃, pH 6.0, and Alkaline Carboxymethyl Cellulase (CMCase) activity 24.34 U/mL. The microbial system C efficiently degrades straw at low temperature, which is valuable for improving the comprehensive utilization rate of straw and has a broad application prospect in improving soil fertility.