Metabolic engineering of Thermoanaerobacterium AK17 for increased ethanol production in seaweed hydrolysate

Biotechnology for Biofuels and Bioproducts

Research

Eva Nordberg Karlsson¹  Leila Allahgholi¹  Bryndís Bjornsdottir²  Ólafur H. Friðjónsson³  Guðmundur Óli Hreggviðsson³  Antoine Moenaert³  Einar Baldvin Haraldsson³  Jóhann Örlygsson⁴  Sigríður Sigurðardóttir⁴  Isabella Zangl⁵  Anna Zieri⁵ 

[1] Biotechnology, Department of Chemistry, Lund University, Lund, Sweden;Department of Biotechnology, Matís Ohf, Reykjavík, Iceland;Department of Biotechnology, Matís Ohf, Reykjavík, Iceland;Faculty of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland;Faculty of Natural Resource Sciences, University of Akureyri, Akureyri, Iceland;IMC University of Applied Sciences Krems, Krems, Austria;

关键词: Macroalgae;    Seaweed;    Biorefinery;    Fermentation;    Biofuel;    Ethanol;    Metabolic engineering;    Thermophile;   

DOI  :  10.1186/s13068-023-02388-y

 received in 2023-07-10, accepted in 2023-09-01,  发布年份 2023

来源: Springer

【 摘 要 】

Sustainably produced renewable biomass has the potential to replace fossil-based feedstocks, for generation of biobased fuels and chemicals of industrial interest, in biorefineries. In this context, seaweeds contain a large fraction of carbohydrates that are a promising source for enzymatic and/or microbial biorefinery conversions. The thermoanaerobe Thermoanaerobacterium AK17 is a versatile fermentative bacterium producing ethanol, acetate and lactate from various sugars. In this study, strain AK17 was engineered for more efficient production of ethanol by knocking out the lactate and acetate side-product pathways. This was successfully achieved, but the strain reverted to acetate production by recruiting enzymes from the butyrate pathway. Subsequently this pathway was knocked out and the resultant strain AK17_M6 could produce ethanol close to the maximum theoretical yield (90%), leading to a 1.5-fold increase in production compared to the wild-type strain. Strain AK17 was also shown to successfully ferment brown seaweed hydrolysate from Laminaria digitata to ethanol in a comparatively high yield of 0.45 g/g substrate, with the primary carbon sources for the fermentations being mannitol, laminarin-derived glucose and short laminari-oligosaccharides. As strain AK17 was successfully engineered and has a wide carbohydrate utilization range that includes mannitol from brown seaweed, as well as hexoses and pentoses found in both seaweeds and lignocellulose, the new strain AK17_M6 obtained in this study is an interesting candidate for production of ethanol from both second and third generations biomass.

【 授权许可】

CC BY   
© BioMed Central Ltd., part of Springer Nature 2023

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