Efficient production of isobutanol from glycerol in Klebsiella pneumoniae: Regulation of acetohydroxyacid synthase, a rate-limiting enzyme in isobutanol biosynthesis

Glycerol is an abundant and inexpensive resource that can be used to produce valuable industrial products. Isobutanol is an important industrial chemical that has been studied for biosynthesis from various carbon sources and microorganisms. So far, isobutanol production by Klebsiella pneumoniae has...

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Bibliographic Details
Published in:Renewable energy 2024-03, Vol.223, p.120010, Article 120010
Main Authors: Jo, Min-Ho, Heo, Sun-Yeon, Ju, Jung-Hyun, Jeong, Ki Jun, Oh, Baek-Rock
Format: Article
Language:English
Subjects:
Acetohydroxyacid synthase
acetolactate synthase
agitation
biosynthesis
carbon
enzyme activity
feedstocks
gene expression
glucose
Glycerol
Isobutanol
isozymes
Klebsiella pneumoniae
mutants
plasmids
Regulation at gene expression level
renewable energy sources
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Summary:Glycerol is an abundant and inexpensive resource that can be used to produce valuable industrial products. Isobutanol is an important industrial chemical that has been studied for biosynthesis from various carbon sources and microorganisms. So far, isobutanol production by Klebsiella pneumoniae has mainly been studied using glucose. In this study, we produced isobutanol from glycerol based on the K. pneumoniae ΔldhAΔbudA mutant harboring pBR-iBO, which was used in a previous study with K. pneumoniae. We investigated the effect of different acetohydroxyacid synthase (AHAS) isoenzymes (rate-limiting enzymes in isobutanol biosynthesis), plasmid copy number, and different promoters as a method to increase isobutanol production through regulation at gene expression level. The K. pneumoniae Cu ΔldhAΔbudA, pUC-tac-BN-ISO strain produced 2.56-fold more isobutanol than reported previously for glycerol-derived isobutanol production. Additionally, the in vitro enzyme activity of AHAS I (ilvBN) was greater than that of the other two isoenzymes (ilvIH and ilvGM). The evaluation of process factors indicated that an agitation speed of 200 rpm with the culture maintained at pH 6.0 was a favorable condition for isobutanol production (1.02 g/L). Our results demonstrated enhanced production of isobutanol from glycerol and provide insights for future research on isobutanol production from renewable feedstock. [Display omitted]
ISSN:0960-1481
1879-0682
DOI:10.1016/j.renene.2024.120010