Metabolic engineering of bacteria for utilization of mixed sugar substrates for improved production of chemicals and fuel ethanol

Jojima, Toru; Inui, Masayuki; Yukawa, Hideaki

doi:10.4155/bfs.11.9

Cited by 6 publications

(1 citation statement)

References 84 publications

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“…Deleting gene ptsG makes E. coli co-utilize arabinose with glucose, although xylose utilization remains repressed by arabinose. Further attempts to replace the native crp gene with a cAMP-independent mutant without CCR can facilitate the simultaneous utilization of glucose, arabinose, and xylose [ 39 ]. A cis-acting DNA element known as the catabolite responsive element ( cre ) located within the open reading frame of xylA contributes to the CCR of xylose; accordingly, the strain with an inactivated cre site in xylA could consume fructose and xylose simultaneously [ 40 ], but this strain still exhibited diauxic growth on glucose and xylose.…”

Section: Resultsmentioning

confidence: 99%

Omics analysis coupled with gene editing revealed potential transporters and regulators related to levoglucosan metabolism efficiency of the engineered Escherichia coli

Chang

Wang

Islam

et al. 2022

Biotechnol Biofuels

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Background Bioconversion of levoglucosan, a promising sugar derived from the pyrolysis of lignocellulose, into biofuels and chemicals can reduce our dependence on fossil-based raw materials. However, this bioconversion process in microbial strains is challenging due to the lack of catalytic enzyme relevant to levoglucosan metabolism, narrow production ranges of the native strains, poor cellular transport rate of levoglucosan, and inhibition of levoglucosan metabolism by other sugars co-existing in the lignocellulose pyrolysate. The heterologous expression of eukaryotic levoglucosan kinase gene in suitable microbial hosts like Escherichia coli could overcome the first two challenges to some extent; however, no research has been dedicated to resolving the last two issues till now. Results Aiming to resolve the two unsolved problems, we revealed that seven ABC transporters (XylF, MalE, UgpB, UgpC, YtfQ, YphF, and MglA), three MFS transporters (KgtP, GntT, and ActP), and seven regulatory proteins (GalS, MhpR, YkgD, Rsd, Ybl162, MalM, and IraP) in the previously engineered levoglucosan-utilizing and ethanol-producing E. coli LGE2 were induced upon exposure to levoglucosan using comparative proteomics technique, indicating these transporters and regulators were involved in the transport and metabolic regulation of levoglucosan. The proteomics results were further verified by transcriptional analysis of 16 randomly selected genes. Subsequent gene knockout and complementation tests revealed that ABC transporter XylF was likely to be a levoglucosan transporter. Molecular docking showed that levoglucosan can bind to the active pocket of XylF by seven H-bonds with relatively strong strength. Conclusion This study focusing on the omics discrepancies between the utilization of levoglucosan and non-levoglucosan sugar, could provide better understanding of levoglucosan transport and metabolism mechanisms by identifying the transporters and regulators related to the uptake and regulation of levoglucosan metabolism. The protein database generated from this study could be used for further screening and characterization of the transporter(s) and regulator(s) for downstream enzymatic/genetic engineering work, thereby facilitating more efficient microbial utilization of levoglucosan for biofuels and chemicals production in future.

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Section: Resultsmentioning

confidence: 99%