Kapoor M, Kapoor R K, Kuhad R C
Lignocellulose Biotechnology Laboratory, Department of Microbiology, University of Delhi South Campus, New Delhi, India.
J Appl Microbiol. 2007 Aug;103(2):305-17. doi: 10.1111/j.1365-2672.2006.03251.x.
Investigation of waste pulps and soda pulp bleaching with xylanase (X) and laccase mediator system (LMS) alone and in conjunction (one after the other) (XLMS).
Soda and different grades of waste pulp fibres [used for making three-layered duplex sheets - top layer (TL), protective layer (PL) and bottom layer (BL)] when pretreated with either xylanase (40.0 IU g(-1)) or LMS (up to 200.0 U g(-1)) alone and in combination (one after the other) (XLMS) exhibited an increase in release of reducing sugars [up to 881.0% soda pulp; up to 736.6% (TL), up to 215.7% (PL) and up to 198.0% (BL) waste pulp], reduction in kappa number [up to 17.6% soda pulp; up to 14.0% (TL), up to 25.3% (PL) and up to 10.9% (BL), waste pulp], improvement in brightness [up to 20.4% soda pulp; up to 23.6% (TL), up to 8.6% (PL) and up to 5.0% (BL), waste pulp] when compared with the respective controls. The usage of XLMS along with 15% reduced level of hypochlorite at CEHHXLMS/EHHXLMS bleaching stage reduced kappa number [5.5% soda pulp; 11.4% (TL), 7.9% (PL), waste pulp] and improved brightness [1.0% soda pulp; 0.9% (TL), 1.4% (PL) waste pulp] when compared with the controls. Scanning electron microscopic studies revealed development of cracks, flakes, pores and peeling off the fibres in the enzyme-treated pulp samples. These modifications of the fibre surface during enzymatic bleaching in turn indicated the removal of lignin and derived compounds from the fibre cell wall.
The work describes synergistic action of xylanase with LMS for bleaching of waste and nonwood pulps for eco-friendly production of paper and thus reveals a new unexploited arena for enzyme-based pulp bleaching.
The drastic improvement in pulp properties obtained after xylanase and LMS treatment would improve the competitiveness of enzyme-based, environmentally benign processes over chemicals both economically and environmentally.
研究木聚糖酶（X）和漆酶介导体系（LMS）单独及联合使用（先后依次使用）（XLMS）对废纸浆和苏打浆的漂白效果。
苏打浆和不同等级的废纸浆纤维[用于制作三层双面纸——顶层（TL）、保护层（PL）和底层（BL）]，单独用木聚糖酶（40.0 IU g⁻¹）或LMS（最高200.0 U g⁻¹）预处理，以及联合使用（先后依次使用）（XLMS）后，还原糖释放量增加[苏打浆最高可达881.0%；（TL）最高可达736.6%，（PL）最高可达215.7%，（BL）最高可达198.0%废纸浆]，卡伯值降低[苏打浆最高可达17.6%；（TL）最高可达14.0%，（PL）最高可达25.3%，（BL）最高可达10.9%废纸浆]，白度提高[苏打浆最高可达20.4%；（TL）最高可达23.6%，（PL）最高可达8.6%，（BL）最高可达5.0%废纸浆]，与各自的对照相比。在CEHHXLMS/EHHXLMS漂白阶段，XLMS与次氯酸盐用量降低15%联合使用时，与对照相比，卡伯值降低[苏打浆降低5.5%；（TL）降低11.4%，（PL）降低7.9%废纸浆]，白度提高[苏打浆提高1.0%；（TL）提高0.9%，（PL）提高1.4%废纸浆]。扫描电子显微镜研究显示，酶处理后的纸浆样品中纤维出现裂缝、片状剥落、孔隙和纤维剥离现象。酶法漂白过程中纤维表面的这些变化反过来表明从纤维细胞壁中去除了木质素及其衍生化合物。
该研究描述了木聚糖酶与LMS在废纸浆和非木浆漂白中的协同作用，以实现环保型纸张生产，从而揭示了基于酶的纸浆漂白这一未被开发的新领域。
木聚糖酶和LMS处理后纸浆性能的显著改善将在经济和环境方面提高基于酶的环境友好型工艺相对于化学工艺的竞争力。
