The role of two Trichoderma reesei xylanases in the bleaching of pine kraft pulp

Johanna Buchert (Corresponding Author), Marjatta Ranua, Anne Kantelinen, Liisa Viikari

Research output: Contribution to journalArticleScientificpeer-review

62 Citations (Scopus)


The two major xylanases of Trichoderma reesei with different pI values and pH optima were compared for increasing the bleachability of pine kraft pulp. The efficiencies of the two enzymes acting on pulp substrate were very similar in hydrolysis yield, extraction kappa number or final brightness value. Only slight synergism between the two enzymes was observed in both hydrolysis and bleaching tests. The pH optimum of the pI 5.5 xylanase was similar in pulp treatment and in the hydrolysis of isolated substrates, and the bleaching result also correlated well with the hydrolysis of pulp xylan. By contrast, the pI 9.0 xylanase acted differently on pulp than on isolated xylans at different pH values and the pH optimum on pulp was increased. The bleachability of pulp by the pI 9.0 xylanase was improved more than expected at pH 7.0, although the hydrolysis of pulp xylan was substantially decreased. A similar phenomenon was also observed when the hydrolysis was performed in water instead of buffer. It thus appears that the degree of hydrolysis needed to obtain improved bleachability with pI 9.0 xylanase can be minimized by proper adjustment of the hydrolysis conditions.
Original languageEnglish
Pages (from-to)825-829
JournalApplied Microbiology and Biotechnology
Issue number6
Publication statusPublished - 1992
MoE publication typeA1 Journal article-refereed


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