Co-production of ethanol and squalene using a Saccharomyces cerevisiae ERG1 (squalene epoxidase) mutant and agro-industrial feedstock

Hull, Claire M, Loveridge, Edric Joel, Rolley, Nicola J, Donnison, Iain S, Kelly, Steven L and Kelly, Diane E 2014. Co-production of ethanol and squalene using a Saccharomyces cerevisiae ERG1 (squalene epoxidase) mutant and agro-industrial feedstock. Biotechnology for Biofuels 7 (1) , 133. 10.1186/s13068-014-0133-7

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Abstract

Background: Genetically customised Saccharomyces cerevisiae that can produce ethanol and additional bio-based chemicals from sustainable agro-industrial feedstocks (for example, residual plant biomass) are of major interest to the biofuel industry. We investigated the microbial biorefinery concept of ethanol and squalene co-production using S. cerevisiae (strain YUG37- ERG1 ) wherein ERG1 (squalene epoxidase) transcription is under the control of a doxycycline-repressible tet0 7 -CYC1 promoter. The production of ethanol and squalene by YUG37- ERG1 grown using agriculturally sourced grass juice supplemented with doxycycline was assessed. Results: Use of the tet0 7 -CYC1 promoter permitted regulation of ERG1 expression and squalene accumulation in YUG37- ERG1, allowing us to circumvent the lethal growth phenotype seen when ERG1 is disrupted completely. In experiments using grass juice feedstock supplemented with 0 to 50 μ g doxycycline mL − 1 , YUG37- ERG1 fermented ethanol (22.5 [±0.5] mg mL − 1 ) and accumulated the highest squalene content (7.89 ± 0.25 mg g − 1 dry biomass) and yield (18.0 ± 4.18 mg squalene L − 1 ) with supplements of 5.0 and 0.025 μ g doxycycline mL − 1 , respectively. Grass juice was found to be rich in water-soluble carbohydrates (61.1 [±3.6] mg sugars mL − 1 ) and provided excellent feedstock for growth and fermentation studies using YUG37- ERG1 . Conclusion: Residual plant biomass components from crop production and rotation systems represent possible substrates for microbial fermentation of biofuels and bio-based compounds. This study is the first to utilise S. cerevisiae for the co-production of ethanol and squalene from grass juice. Our findings underscore the value of the biorefinery approach and demonstrate the potential to integrate microbial bioprocess engineering with existing agriculture.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Chemistry
Subjects:	Q Science > QD Chemistry
Additional Information:	This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://​creativecommons.​org/​publicdomain/​zero/​1.​0/​) applies to the data made available in this article, unless otherwise stated.
Publisher:	BioMed Central
ISSN:	1754-6834
Date of First Compliant Deposit:	30 March 2016
Last Modified:	23 May 2023 14:34
URI:	https://orca.cardiff.ac.uk/id/eprint/87772

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