Abstract
The objective of this project was to ferment lactose and whey to ethanol in one-step process. Models of cell
factory of non-engineered S.cerevisiae have been proposed to ferment lactose. The cell factory of non-engineered
S. cerevisiae/SG-lactase was prepared by the addition, of a starch gel solution containing lactase on non-engineered
S. cerevisiae, and freeze drying of it. The 2-layer non engineered S.cerevisiae-TC/SG-lactase factory was prepared
by immobilizing S. cerevisiae on the internal layer of tubular cellulose (TC), and the lactase enzyme was contained
in the upper layer of starch gel (SG) covering cells of S. cerevisiae. Using such cell factory for the
fermentation of lactose, alcohol yield of 23-32 mL/L at lactose conversion of 71-100%. The improvement in
alcohol yield by cell factory versus co-immobilization of lactase enzyme and S. cerevisiae on alginates, was found
in the range of 28-78%. Likewise, the cell factories are more effective than engineered S. cerevisiae. The
fermentation of whey instead of lactose resulted in a significant reduction of the fermentation time. Freeze-dried
cell factories led to improved results as compared with non-freeze dried. When lactase was substituted with
L. casei, ethanol and lactic acid were produced simultaneously at high concentrations, but in a much longer
fermentation time. The cell factories can be considered as models for white biotechnology using lactose containing
raw materials. This suggested cell factory model can be applied for other bioconversions using the
appropriate enzymes and cells, in the frame of White Biotechnology without genetic modification.
factory of non-engineered S.cerevisiae have been proposed to ferment lactose. The cell factory of non-engineered
S. cerevisiae/SG-lactase was prepared by the addition, of a starch gel solution containing lactase on non-engineered
S. cerevisiae, and freeze drying of it. The 2-layer non engineered S.cerevisiae-TC/SG-lactase factory was prepared
by immobilizing S. cerevisiae on the internal layer of tubular cellulose (TC), and the lactase enzyme was contained
in the upper layer of starch gel (SG) covering cells of S. cerevisiae. Using such cell factory for the
fermentation of lactose, alcohol yield of 23-32 mL/L at lactose conversion of 71-100%. The improvement in
alcohol yield by cell factory versus co-immobilization of lactase enzyme and S. cerevisiae on alginates, was found
in the range of 28-78%. Likewise, the cell factories are more effective than engineered S. cerevisiae. The
fermentation of whey instead of lactose resulted in a significant reduction of the fermentation time. Freeze-dried
cell factories led to improved results as compared with non-freeze dried. When lactase was substituted with
L. casei, ethanol and lactic acid were produced simultaneously at high concentrations, but in a much longer
fermentation time. The cell factories can be considered as models for white biotechnology using lactose containing
raw materials. This suggested cell factory model can be applied for other bioconversions using the
appropriate enzymes and cells, in the frame of White Biotechnology without genetic modification.
| Original language | English |
|---|---|
| Article number | 109750 |
| Number of pages | 6 |
| Journal | Enzyme and Microbial Technology |
| Volume | 145 |
| Early online date | 6 Feb 2021 |
| DOIs | |
| Publication status | Published (in print/issue) - 30 Apr 2021 |
Bibliographical note
Funding Information:We acknowledge support of this work by the project “Research Infrastructure on Food Bioprocessing Development and Innovation Exploitation – Food Innovation RI” (MIS 5027222), which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" ( NSRF 2014-2020 ) and co-financed by Greece and the European Union (European Regional Development Fund) .
Publisher Copyright:
© 2021 Elsevier Inc.
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
Keywords
- Cell-factory
- S. cerevisiae
- lactose
- fermentation
- whey
