Effects of Bacterial-Enzyme Synergy on Cell Wall Components and Microbial Diversity During Tobacco Stem Fermentation

Low-value agricultural by-products can be enhanced in terms of their utility by fermentation with functional microbes or enzymatic hydrolysis to reduce cell wall material content. However, the use of a single bacteria or enzyme often results in low efficiency and instability in reducing cell wall materials, which limits the application of microorganisms in production. This study utilized Bacillus megaterium with cell wall degrading abilities, extracellular enzymes, and bacterial-enzyme complexes to treat tobacco stems, analyzing the cell wall material content, enzyme activity, and diversity of attached microorganisms under different treatments. The results demonstrated that all three treatments increased the activity of cell wall degrading enzymes and reduced cell wall material content during tobacco stem fermentation. Compared to the control group, the bacterial-enzyme synergy treatment group showed reductions of 51.33% in cellulose, 57.89% in lignin, and 34.88% in pectin. There is a significant negative correlation between cellulose content and abundance of Bacillus subtilis. All three treatment groups significantly increased the community abundance of Bacillus megaterium, a cell wall degrading bacterium, and enriched cell wall degradation functional genes, with the bacterial-enzyme synergy group showing the most notable effects. In conclusion, under the bacterial-enzyme synergy treatment conditions, there was a significant increase in the abundance of functional microorganisms related to the degradation of tobacco stem cell wall materials, along with a significant reduction in cell wall material content.