Solid state fermentation improves the utilization value of cotton stalk

The traditional methods of disposing of waste cotton straw, such as incineration or returning it to the field, often lead to resource wastage and significant environmental issues. Herein, a solid-state fermentation strategy is proposed aimed at enhancing the quality of cotton straw as an alternative feedstock . The fermentation process involves Bacillus F4 ( Paenibacillus sp. ) and T11 ( Bacillus amylolyticus ), with results indicating that the Bacillus F4 group exhibit the most significant increase in true protein (TP) content. To optimize the fermentation conditions, both single-factor and orthogonal tests are conducted, leading to the determination of optimal parameters: a fermentation temperature of 30℃, a duration of 8 days, a material-to-water ratio of 1:1.2, and the addition of 25 % seed liquid, 25 % corn flour, and 2 % urea. Key factors influencing the fermentation process include urea addition, fermentation time, material-to-water ratio, fermentation temperature, bacterial liquid addition, and corn flour addition. Under these optimized conditions, solid-state fermentation of CS using Bacillus F4 is performed. The results demonstrate significant increases in true protein and crude protein levels ( P < 0.05), alongside a significant reduction in gossypol content ( P < 0.01). These findings offer valuable insights into the application of solid-state fermentation for cotton straw, promoting the sustainable reuse of cotton processing waste in the field of feed materials.