TY - JOUR
T1 - Cellulase recycling in high-solids enzymatic hydrolysis of pretreated empty fruit bunches
AU - Kim, Jae Kyun
AU - Yang, Jungwoo
AU - Park, So Young
AU - Yu, Ju Hyun
AU - Kim, Kyoung Heon
N1 - Funding Information:
We want to acknowledge the grant supports from the Ministry of Trade, Industry & Energy of Korea (10049674) and the Basic Research Laboratory Pro‑ gram (NRF‑2018R1A4A1022589) through the National Research Foundation of Korea funded by the MSIT. The article‑processing charge was supported by BK21 PLUS Program for School of Life Sciences and Biotechnology, Korea University. This work was performed at the Korea University Food Safety Hall for the Institute of Biomedical Science and Food Safety.
Funding Information:
The Ministry of Trade, Industry & Energy of Korea (10049674) and the Basic Research Laboratory Program (NRF‑2018R1A4A1022589) through the National Research Foundation of Korea funded by the MSIT.
Publisher Copyright:
© 2019 The Author(s).
PY - 2019/6/6
Y1 - 2019/6/6
N2 - Background: The lignocellulosic biomass feedstocks such as empty fruit bunches (EFBs) prove to be potential renewable resources owing to their abundance, low prices, and high carbohydrate contents. Generally, the conversion of lignocellulosic biomass into chemicals, fuels, and materials mainly includes pretreatment, enzymatic hydrolysis, fermentation, and recovery of final products. To increase the economic viability of such processes, the cost of cellulase production and enzymatic hydrolysis should be reduced. For this, recycling cellulase can be considered for reducing the saccharification cost of lignocellulose. In this study, cellulase recycling for high-solids enzymatic hydrolysis (i.e., 20%) was evaluated in saccharification of hydrothermally-pretreated EFBs. Results: High-solids (20%) enzymatic hydrolysis of hydrothermally-pretreated empty fruit bunches with 40 FPU of Cellic CTec3/g glucan was carried out for cellulase recycling. In the second round of hydrolysis using a recycled enzyme, only 19.3% of glucose yield was obtained. The most important limiting factors for cellulase recycling of this study were identified as the enzyme inhibition by glucose, the loss of enzyme activities, and the non-productive binding of enzymes to insoluble biomass solids. To overcome these limitations, PEG was added prior to the first-round hydrolysis to reduce non-productive enzyme binding, glucose was removed from the enzyme fraction to be reused in the second-round hydrolysis, and EFB solids from the first-round hydrolysis were used in the second-round hydrolysis. These three additional measures with cellulase recycling resulted in a 3.5 times higher glucose yield (i.e., 68.0%) at the second round than that of the control, the second-round hydrolysis with cellulase recycling but without these measures. Conclusions: Because of the high obstacles found in this study in achieving high saccharification yields in the high-solids saccharification of high-lignin lignocellulose with cellulase recycling, effective measures for improving enzymatic saccharification yields need to be accompanied with cellulase recycling.
AB - Background: The lignocellulosic biomass feedstocks such as empty fruit bunches (EFBs) prove to be potential renewable resources owing to their abundance, low prices, and high carbohydrate contents. Generally, the conversion of lignocellulosic biomass into chemicals, fuels, and materials mainly includes pretreatment, enzymatic hydrolysis, fermentation, and recovery of final products. To increase the economic viability of such processes, the cost of cellulase production and enzymatic hydrolysis should be reduced. For this, recycling cellulase can be considered for reducing the saccharification cost of lignocellulose. In this study, cellulase recycling for high-solids enzymatic hydrolysis (i.e., 20%) was evaluated in saccharification of hydrothermally-pretreated EFBs. Results: High-solids (20%) enzymatic hydrolysis of hydrothermally-pretreated empty fruit bunches with 40 FPU of Cellic CTec3/g glucan was carried out for cellulase recycling. In the second round of hydrolysis using a recycled enzyme, only 19.3% of glucose yield was obtained. The most important limiting factors for cellulase recycling of this study were identified as the enzyme inhibition by glucose, the loss of enzyme activities, and the non-productive binding of enzymes to insoluble biomass solids. To overcome these limitations, PEG was added prior to the first-round hydrolysis to reduce non-productive enzyme binding, glucose was removed from the enzyme fraction to be reused in the second-round hydrolysis, and EFB solids from the first-round hydrolysis were used in the second-round hydrolysis. These three additional measures with cellulase recycling resulted in a 3.5 times higher glucose yield (i.e., 68.0%) at the second round than that of the control, the second-round hydrolysis with cellulase recycling but without these measures. Conclusions: Because of the high obstacles found in this study in achieving high saccharification yields in the high-solids saccharification of high-lignin lignocellulose with cellulase recycling, effective measures for improving enzymatic saccharification yields need to be accompanied with cellulase recycling.
KW - Cellulase recycling
KW - Empty fruit bunches
KW - Enzymatic hydrolysis
KW - High-solids loading
KW - Hydrothermal pretreatment
KW - Lignocellulose
UR - http://www.scopus.com/inward/record.url?scp=85067125662&partnerID=8YFLogxK
U2 - 10.1186/s13068-019-1476-x
DO - 10.1186/s13068-019-1476-x
M3 - Article
AN - SCOPUS:85067125662
VL - 12
JO - Biotechnology for Biofuels
JF - Biotechnology for Biofuels
SN - 1754-6834
IS - 1
M1 - 138
ER -
