BioChem - DOS

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

Biotechnology for biofuels

Hull, Claire M; Loveridge, E Joel; Rolley, Nicola J; Donnison, Iain S; Kelly, Steven L; Kelly, Diane E

<P><B>Background</B></P><P>Genetically customised <I>Saccharomyces cerevisiae</I> 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 <I>S. cerevisiae</I> (strain YUG37-<I>ERG1</I>) wherein <I>ERG1</I> (squalene epoxidase) transcription is under the control of a doxycycline-repressible <I>tet0</I><SUB><I>7</I></SUB><I>-CYC1</I> promoter. The production of ethanol and squalene by YUG37-<I>ERG1</I> grown using agriculturally sourced grass juice supplemented with doxycycline was assessed.</P><P><B>Results</B></P><P>Use of the <I>tet0</I><SUB><I>7</I></SUB><I>-CYC1</I> promoter permitted regulation of <I>ERG1</I> expression and squalene accumulation in YUG37-<I>ERG1,</I> allowing us to circumvent the lethal growth phenotype seen when <I>ERG1</I> is disrupted completely. In experiments using grass juice feedstock supplemented with 0 to 50&nbsp;&mu;g doxycycline mL<SUP>&#x2212;1</SUP>, YUG37-<I>ERG1</I> fermented ethanol (22.5 [±0.5] mg mL<SUP>&#x2212;1</SUP>) and accumulated the highest squalene content (7.89 ± 0.25&nbsp;mg&nbsp;g<SUP>&#x2212;1</SUP> dry biomass) and yield (18.0 ± 4.18&nbsp;mg squalene L<SUP>&#x2212;1</SUP>) with supplements of 5.0 and 0.025&nbsp;&mu;g doxycycline mL<SUP>&#x2212;1</SUP>, respectively. Grass juice was found to be rich in water-soluble carbohydrates (61.1 [±3.6] mg sugars mL<SUP>&#x2212;1</SUP>) and provided excellent feedstock for growth and fermentation studies using YUG37-<I>ERG1</I>.</P><P><B>Conclusion</B></P><P>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 <I>S. cerevisiae</I> 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.</P>

2014

BioMed Central

cc-by

1754-6834

7

pp.133

10.1186/preaccept-1839828871199897

http://click.ndsl.kr/servlet/OpenAPIDetailView?keyValue=05787966&target=NART&cn=NART71814918

https://biotechnologyforbiofuels.biomedcentral.com/track/pdf/10.1186/s13068-014-0133-7

Bio-based products; ERG1; Ethanol; Sterol; Squalene; Squalene epoxidase