Enhanced production of cellobiohydrolases in Trichoderma reesei and evaluation of the new preparations in biofinishing of cotton
In the search for suitable cellulase combinations for industrial biofinishing of cotton, five different types of Trichoderma reesei strains were constructed for elevated cellobiohydrolase production: CBHI overproducers with and without endoglucanase I (EGI), CBHII overproducers with and without endo...
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Veröffentlicht in: | Journal of biotechnology 2005-03, Vol.116 (3), p.305-317 |
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Zusammenfassung: | In the search for suitable cellulase combinations for industrial biofinishing of cotton, five different types of
Trichoderma reesei strains were constructed for elevated cellobiohydrolase production: CBHI overproducers with and without endoglucanase I (EGI), CBHII overproducers with and without endoglucanase II (EGII) and strains overproducing both CBHI and CBHII without the major endoglucanases I and II. One additional copy of
cbh1 gene increased production of CBHI protein 1.3-fold, and two copies 1.5-fold according to ELISA (enzyme-linked immunosorbent assay). The level of total secreted proteins was increased in CBHI transformants as compared to the host strain. One copy of the
cbh2 expression cassette in which the
cbh2 was expressed from the
cbh1 promoter increased production of CBHII protein three- to four-fold when compared to the host strain.
T. reesei strains producing elevated amounts of both CBHI and CBHII without EGI and EGII were constructed by replacing the
egl1 locus with the coding region of the
cbh1 gene and the
egl2 locus with the coding region of
cbh2. The
cbh1 was expressed from its own promoter and the
cbh2 gene using either the
cbh1 or
cbh2 promoter. Production of CBHI by the CBH-transformants was increased up to 1.6-fold and production of CBHII up to 3.4-fold as compared with the host strain. Approximately similar amounts of CBHII protein were produced by using
cbh1 or
cbh2 promoters. When the enzyme preparation with elevated CBHII content was used in biofinishing of cotton, better depilling and visual appearance were achieved than with the wild type preparation; however, the improvement was not as pronounced as with preparations with elevated levels of endoglucanases (EG). |
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ISSN: | 0168-1656 1873-4863 |
DOI: | 10.1016/j.jbiotec.2004.10.017 |