Impacts of cellulase deactivation at the moving air–liquid interface on cellulose conversions at low enzyme loadings
Abstract Background We recently confirmed that the deactivation of T. reesei cellulases at the air–liquid interface reduces microcrystalline cellulose conversion at low enzyme loadings in shaken flasks. It is one of the main causes for lowering of cellulose conversions at low enzyme loadings. Howeve...
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Online Access: | http://link.springer.com/article/10.1186/s13068-019-1439-2 |
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doaj-f8c6f45155f344b0a53bdd5df6b4c8372020-11-25T03:02:43ZengBMCBiotechnology for Biofuels1754-68342019-04-0112111510.1186/s13068-019-1439-2Impacts of cellulase deactivation at the moving air–liquid interface on cellulose conversions at low enzyme loadingsSamarthya Bhagia0Charles E. Wyman1Rajeev Kumar2Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California RiversideDepartment of Chemical and Environmental Engineering, Bourns College of Engineering, University of California RiversideCenter for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California RiversideAbstract Background We recently confirmed that the deactivation of T. reesei cellulases at the air–liquid interface reduces microcrystalline cellulose conversion at low enzyme loadings in shaken flasks. It is one of the main causes for lowering of cellulose conversions at low enzyme loadings. However, supplementing cellulases with small quantities of surface-active additives in shaken flasks can increase cellulose conversions at low enzyme loadings. It was also shown that cellulose conversions at low enzyme loadings can be increased in unshaken flasks if the reactions are carried for a longer time. This study further explores these recent findings to better understand the impact of air–liquid interfacial phenomena on enzymatic hydrolysis of cellulose contained in Avicel, Sigmacell, α-cellulose, cotton linters, and filter paper. The impacts of solids and enzyme loadings, supplementation with nonionic surfactant Tween 20 and xylanases, and application of different types of mixing and reactor designs on cellulose hydrolysis were also evaluated. Results Avicel cellulose conversions at high solid loading were more than doubled by minimizing loss of cellulases to the air–liquid interface. Maximum cellulose conversions were high for surface-active supplemented shaken flasks or unshaken flasks because of low cellulase deactivation at the air–liquid interface. The nonionic surfactant Tween 20 was unable to completely prevent cellulase deactivation in shaken flasks and only reduced cellulose conversions at unreasonably high concentrations. Conclusions High dynamic interfacial areas created through baffles in reactor vessels, low volumes in high-capacity vessels, or high shaking speeds severely limited cellulose conversions at low enzyme loadings. Precipitation of cellulases due to aggregation at the air–liquid interface caused their continuous deactivation in shaken flasks and severely limited solubilization of cellulose.http://link.springer.com/article/10.1186/s13068-019-1439-2CelluloseCellulaseDeactivationHydrolysisAir–liquid interfaceGas–liquid interface |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Samarthya Bhagia Charles E. Wyman Rajeev Kumar |
spellingShingle |
Samarthya Bhagia Charles E. Wyman Rajeev Kumar Impacts of cellulase deactivation at the moving air–liquid interface on cellulose conversions at low enzyme loadings Biotechnology for Biofuels Cellulose Cellulase Deactivation Hydrolysis Air–liquid interface Gas–liquid interface |
author_facet |
Samarthya Bhagia Charles E. Wyman Rajeev Kumar |
author_sort |
Samarthya Bhagia |
title |
Impacts of cellulase deactivation at the moving air–liquid interface on cellulose conversions at low enzyme loadings |
title_short |
Impacts of cellulase deactivation at the moving air–liquid interface on cellulose conversions at low enzyme loadings |
title_full |
Impacts of cellulase deactivation at the moving air–liquid interface on cellulose conversions at low enzyme loadings |
title_fullStr |
Impacts of cellulase deactivation at the moving air–liquid interface on cellulose conversions at low enzyme loadings |
title_full_unstemmed |
Impacts of cellulase deactivation at the moving air–liquid interface on cellulose conversions at low enzyme loadings |
title_sort |
impacts of cellulase deactivation at the moving air–liquid interface on cellulose conversions at low enzyme loadings |
publisher |
BMC |
series |
Biotechnology for Biofuels |
issn |
1754-6834 |
publishDate |
2019-04-01 |
description |
Abstract Background We recently confirmed that the deactivation of T. reesei cellulases at the air–liquid interface reduces microcrystalline cellulose conversion at low enzyme loadings in shaken flasks. It is one of the main causes for lowering of cellulose conversions at low enzyme loadings. However, supplementing cellulases with small quantities of surface-active additives in shaken flasks can increase cellulose conversions at low enzyme loadings. It was also shown that cellulose conversions at low enzyme loadings can be increased in unshaken flasks if the reactions are carried for a longer time. This study further explores these recent findings to better understand the impact of air–liquid interfacial phenomena on enzymatic hydrolysis of cellulose contained in Avicel, Sigmacell, α-cellulose, cotton linters, and filter paper. The impacts of solids and enzyme loadings, supplementation with nonionic surfactant Tween 20 and xylanases, and application of different types of mixing and reactor designs on cellulose hydrolysis were also evaluated. Results Avicel cellulose conversions at high solid loading were more than doubled by minimizing loss of cellulases to the air–liquid interface. Maximum cellulose conversions were high for surface-active supplemented shaken flasks or unshaken flasks because of low cellulase deactivation at the air–liquid interface. The nonionic surfactant Tween 20 was unable to completely prevent cellulase deactivation in shaken flasks and only reduced cellulose conversions at unreasonably high concentrations. Conclusions High dynamic interfacial areas created through baffles in reactor vessels, low volumes in high-capacity vessels, or high shaking speeds severely limited cellulose conversions at low enzyme loadings. Precipitation of cellulases due to aggregation at the air–liquid interface caused their continuous deactivation in shaken flasks and severely limited solubilization of cellulose. |
topic |
Cellulose Cellulase Deactivation Hydrolysis Air–liquid interface Gas–liquid interface |
url |
http://link.springer.com/article/10.1186/s13068-019-1439-2 |
work_keys_str_mv |
AT samarthyabhagia impactsofcellulasedeactivationatthemovingairliquidinterfaceoncelluloseconversionsatlowenzymeloadings AT charlesewyman impactsofcellulasedeactivationatthemovingairliquidinterfaceoncelluloseconversionsatlowenzymeloadings AT rajeevkumar impactsofcellulasedeactivationatthemovingairliquidinterfaceoncelluloseconversionsatlowenzymeloadings |
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