废次烟叶提取液源木质素降解菌Bacillus subtilis SM降解特性

Lignin degrading characteristics of Bacillus subtilis SM isolated from tobacco waste extract

摘要:

【目的】目前造纸法再造烟叶工艺已经成为我国重要的废烟叶处理和利用方式，该工艺中烟梗中高木质素的降解是个挑战性的需解决问题。从废次烟叶提取液(Tobacco waste extract，TWE)中筛选木质素的降解微生物用来直接处理烟梗或烟末提取液，可实现对木质素含量的调控。【方法】将废次烟叶提取液(TWE)浓缩液中分离出的Bacillus subtilis SM接种到以Kraft木质素为唯一碳源的无机盐培养基中，在pH 7.0、30 °C培养基中培养4 d来检测菌株对木质素的降解效果。通过HPLC、TOC、GPC和色度来表征SM对木质素的降解，并采用烟梗无机盐培养基在pH 7.0、30 °C培养4 d检测SM对烟梗木质素的降解。【结果】HPLC结果显示SM在以木质素磺酸钠为唯一碳源的无机盐培养基中可全部降解分子质量为534.5的木质素磺酸钠，而对Kraft木质素降解不明显，仅观察到组分的变化。脱色结果显示脱色率达到40.7%，但在对Kraft木质素矿化方面矿化率只能达到5.4%。SM在烟梗无机盐培养基中可使烟梗失重率分别达到50%以上(对照组为18.9%)，烟梗中木质素含量减少了70%左右。【结论】来源于废次烟叶提取液(TWE)的Bacillus subtilis SM能够以Kraft木质素为唯一碳源生长，也能够有效降解烟梗中的木质素，可应用于烟草废弃物原料中木质素的降解。

Abstract:

[Objective] Reconstituted tobacco technology has been one important method to treat and reuse the tobacco waste, in which ligini degradation in tobacco stem is a challenge key problem to resolve. To realize the flexible control of lignin, tobacco waste extract (TWE) was selected to screen high activity lignin-degrading strains for potential utilizaiton in recontituted tobacco process. [Methods] A lignin-degrading Bacillus subtilis SM isolated from tobacco waste extract (TWE), was inoculated into MSM (mineral salt medium) with kraft lignin (KL) as the sole carbon source and cultured at 30 °C, pH 7.0 for 4 days to detect the efficiency of lignin degradation. The results were analyzed by HPLC, TOC, GPC and chromaticity. The degradation of tobacco stem lignin by SM in MSM was also detected after 4 days culture at pH 7.0 and 30 °C. [Results] Degradation could be achieved for sodium lignosulfonate with Mw=534.5, while no significant degradation and a little compoition change were detected for kraft lignin. The decolorization rate reached 40.7%, while mineralization rate of lignin was only 5.4%. However, the weight loss rate of tobacco stem reached above 50% (while control group is 18.9%), and lignin content in tobacco stem reduced by about 70%. [Conclusion] Bacillus subtilis SM isoalted from tobacco waste extract (TWE) can grow on MSM with kraft lignin as the sole carbon source and degrade the lignin in tobacco stem effectively. It is potential for for liginin degradation of tobacco waste materials.