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

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.