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Improved pulp bleaching potential of Bacillus subtilis WB800 through overexpression of three lignolytic enzymes from various bacteria
Author(s) -
Ozer Aysegul,
Uzuner Ugur,
Guler Halil Ibrahim,
Ay Sal Fulya,
Belduz Ali Osman,
Deniz Ilhan,
Canakci Sabriye
Publication year - 2018
Publication title -
biotechnology and applied biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.468
H-Index - 70
eISSN - 1470-8744
pISSN - 0885-4513
DOI - 10.1002/bab.1637
Subject(s) - bacillus subtilis , pulp (tooth) , laccase , chemistry , pulp and paper industry , kraft process , bacteria , environmentally friendly , kraft paper , food science , lignin , kappa number , enzyme , microbiology and biotechnology , biochemistry , organic chemistry , biology , medicine , ecology , genetics , pathology , engineering
A chemical bleaching process of paper pulps gives off excessive amount of chlorinated organic wastes mostly released to environment without exposing complete bioremediaton. Recent alternative and eco‐friendly approaches toward pulp bleaching appear more responsive to environmental awareness. Here we report, direct use of a recombinant Bacillus subtilis bacterium for pulp bleaching, endowed with three ligninolytic enzymes from various bacteria. In addition, efficient bleaching performance from glutathione‐S‐transferase (GST) biocatalyst tested for the first time in pulp bleaching applications was also achieved. Simultaneous and extracellular overproduction of highly active GST, laccase, and lignin peroxidase catalysts were also performed by Bacillus cells. Both enhanced bleaching success and improved delignification rates were identified when enzyme combinations tested on both pine kraft and waste paper pulps, ranging from 69.75% to 79.18% and 60.89% to 74.65%, respectively. Furthermore, when triple enzyme combination applied onto the papers from pine kraft and waste pulps, the best ISO brightness values were identified as 66.45% and 64.67%, respectively. The delignification rates of pulp fibers exposed to various enzymatic bleaching sequences were comparatively examined under SEM. In conclusion, the current study points out that in near future, a more fined‐tuned engineering of pulp‐colonizing bacteria may become a cost‐effective and environmentally friendly alternative to chemical bleaching.