Cellulose fiber size defines efficiency of enzymatic hydrolysis and impacts degree of synergy between endo- and exoglucanases
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An interplay between cellulases is fundamental in biomass saccharification. Here, the synergistic action of Trichoderma harzianum Cel7A and Cel7B on two cellulosic substrates: bacterial cellulose (BC) and a much more heterogeneous filter paper (FP) was investigated by determining their saccharification yields and by analyzing both the released soluble products and the insoluble reducing ends formed in the process. Furthermore, morphological changes of the substrates were evaluated using scanning electron microscopy. Glycoside hydrolase family 7 (GH7) enzymes introduce uniform changes in BC, whereas in FP they preferentially consume thin microfibrils rather than thicker paper fibers. Thus, the size effect, which leads to a smaller surface area per unit of substrate mass for thicker fibers, seems to play a crucial role in higher enzymatic hydrolysis efficiency of BC as compared to FP. These results demonstrate that the morphology-dependent effects could be essential for the industrial breakdown of cellulose-rich plant biomass.
KeywordsTrichoderma harzianum Cel7A Cel7B Synergism Scanning electron microscopy
We would like to acknowledge support of the Brazilian funding agencies FAPESP via grants 2010/18773-8, 2012/22802-9, 2015/13684-0 and 2016/13602-7 and CNPq via grants 472523/2013-9 and 405191/2015-4. The electron microscopy work has been performed using the Quanta 650 microscope at LME/LNNano/CNPEM, Campinas.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
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