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Optimization of cellulolytic enzyme components through engineering Trichoderma reesei and on-site fermentation using the soluble inducer for cellulosic ethanol production from corn stover.
Biotechnol Biofuels. 2018; 11:49.BB

Abstract

Background

Cellulolytic enzymes produced by Trichoderma reesei are widely studied for biomass bioconversion, and enzymatic components vary depending on different inducers. In our previous studies, a mixture of glucose and disaccharide (MGD) was developed and used to induce cellulase production. However, the enzymatic profile induced by MGD is still not defined, and further optimization of the enzyme cocktail is also required for efficient ethanol production from lignocellulosic biomass.

Results

In this study, cellulolytic enzymes produced by T. reesei Rut C30 using MGD and alkali-pretreated corn stover (APCS) as inducer were compared. Cellular secretome in response to each inducer was analyzed, which revealed a similar enzyme profile. However, significant difference in the content of cellulases and xylanase was detected. Although MGD induction enhanced β-glucosidase production, its activity was still not sufficient for biomass hydrolysis. To overcome such a disadvantage, aabgl1 encoding β-glucosidase in Aspergillus aculeatus was heterologously expressed in T. reesei Rut C30 under the control of the pdc1 promoter. The recombinant T. reesei PB-3 strain showed an improved β-glucosidase activity of 310 CBU/mL in the fed-batch fermentation, 71-folds higher than that produced by the parent strain. Meanwhile, cellulase activity of 50 FPU/mL was detected. Subsequently, the crude enzyme was applied for hydrolyzing corn stover with a solid loading of 20% through separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation, respectively, for ethanol production. Better performance was observed in the SHF process, through which a total of 119.9 g/L glucose was released within 12 h for concomitant ethanol production of 54.2 g/L.

Conclusions

The similar profile of cellulolytic enzymes was detected under the induction of MGD and APCS, but higher amount of cellulases was present in the crude enzyme induced by MGD. However, β-glucosidase activity induced by MGD was not sufficient for hydrolyzing lignocellulosic biomass. High titers of cellulases and β-glucosidase were achieved simultaneously by heterologous expression of aabgl1 in T. reesei and fed-batch fermentation through feeding MGD. We demonstrated that on-site cellulase production by T. reesei PB-3 has a potential for efficient biomass saccharification and ethanol production from lignocellulosic biomass.

Authors+Show Affiliations

1State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240 China. 4Present Address: School of Chemistry and Chemical Engineering, Chongqing University of Science and Technology, Chongqing, 401331 China.2School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116023 China.1State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240 China.1State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240 China.1State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240 China.3Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, 657-8501 Japan.1State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240 China.1State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240 China.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

29483942

Citation

Li, Yong-Hao, et al. "Optimization of Cellulolytic Enzyme Components Through Engineering Trichoderma Reesei and On-site Fermentation Using the Soluble Inducer for Cellulosic Ethanol Production From Corn Stover." Biotechnology for Biofuels, vol. 11, 2018, p. 49.
Li YH, Zhang XY, Zhang F, et al. Optimization of cellulolytic enzyme components through engineering Trichoderma reesei and on-site fermentation using the soluble inducer for cellulosic ethanol production from corn stover. Biotechnol Biofuels. 2018;11:49.
Li, Y. H., Zhang, X. Y., Zhang, F., Peng, L. C., Zhang, D. B., Kondo, A., Bai, F. W., & Zhao, X. Q. (2018). Optimization of cellulolytic enzyme components through engineering Trichoderma reesei and on-site fermentation using the soluble inducer for cellulosic ethanol production from corn stover. Biotechnology for Biofuels, 11, 49. https://doi.org/10.1186/s13068-018-1048-5
Li YH, et al. Optimization of Cellulolytic Enzyme Components Through Engineering Trichoderma Reesei and On-site Fermentation Using the Soluble Inducer for Cellulosic Ethanol Production From Corn Stover. Biotechnol Biofuels. 2018;11:49. PubMed PMID: 29483942.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Optimization of cellulolytic enzyme components through engineering Trichoderma reesei and on-site fermentation using the soluble inducer for cellulosic ethanol production from corn stover. AU - Li,Yong-Hao, AU - Zhang,Xiao-Yue, AU - Zhang,Fei, AU - Peng,Liang-Cai, AU - Zhang,Da-Bing, AU - Kondo,Akihiko, AU - Bai,Feng-Wu, AU - Zhao,Xin-Qing, Y1 - 2018/02/23/ PY - 2017/11/07/received PY - 2018/02/12/accepted PY - 2018/2/28/entrez PY - 2018/2/28/pubmed PY - 2018/2/28/medline KW - Lignocellulosic ethanol KW - On-site cellulase production KW - Soluble inducer KW - Trichoderma reesei KW - β-Glucosidase SP - 49 EP - 49 JF - Biotechnology for biofuels JO - Biotechnol Biofuels VL - 11 N2 - Background: Cellulolytic enzymes produced by Trichoderma reesei are widely studied for biomass bioconversion, and enzymatic components vary depending on different inducers. In our previous studies, a mixture of glucose and disaccharide (MGD) was developed and used to induce cellulase production. However, the enzymatic profile induced by MGD is still not defined, and further optimization of the enzyme cocktail is also required for efficient ethanol production from lignocellulosic biomass. Results: In this study, cellulolytic enzymes produced by T. reesei Rut C30 using MGD and alkali-pretreated corn stover (APCS) as inducer were compared. Cellular secretome in response to each inducer was analyzed, which revealed a similar enzyme profile. However, significant difference in the content of cellulases and xylanase was detected. Although MGD induction enhanced β-glucosidase production, its activity was still not sufficient for biomass hydrolysis. To overcome such a disadvantage, aabgl1 encoding β-glucosidase in Aspergillus aculeatus was heterologously expressed in T. reesei Rut C30 under the control of the pdc1 promoter. The recombinant T. reesei PB-3 strain showed an improved β-glucosidase activity of 310 CBU/mL in the fed-batch fermentation, 71-folds higher than that produced by the parent strain. Meanwhile, cellulase activity of 50 FPU/mL was detected. Subsequently, the crude enzyme was applied for hydrolyzing corn stover with a solid loading of 20% through separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation, respectively, for ethanol production. Better performance was observed in the SHF process, through which a total of 119.9 g/L glucose was released within 12 h for concomitant ethanol production of 54.2 g/L. Conclusions: The similar profile of cellulolytic enzymes was detected under the induction of MGD and APCS, but higher amount of cellulases was present in the crude enzyme induced by MGD. However, β-glucosidase activity induced by MGD was not sufficient for hydrolyzing lignocellulosic biomass. High titers of cellulases and β-glucosidase were achieved simultaneously by heterologous expression of aabgl1 in T. reesei and fed-batch fermentation through feeding MGD. We demonstrated that on-site cellulase production by T. reesei PB-3 has a potential for efficient biomass saccharification and ethanol production from lignocellulosic biomass. SN - 1754-6834 UR - https://www.unboundmedicine.com/medline/citation/29483942/Optimization_of_cellulolytic_enzyme_components_through_engineering_Trichoderma_reesei_and_on_site_fermentation_using_the_soluble_inducer_for_cellulosic_ethanol_production_from_corn_stover_ L2 - https://biotechnologyforbiofuels.biomedcentral.com/articles/10.1186/s13068-018-1048-5 DB - PRIME DP - Unbound Medicine ER -
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