Microbial production of building block chemicals and polymers

Lee, Jeong Wook; Kim, Hyun Uk; Choi, Sangdun; Yi, Jaeyoun; Lee, Sang Yup

doi:10.1016/j.copbio.2011.02.011

Cited by 205 publications

(100 citation statements)

References 53 publications

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“…Products such as antibiotics, amino acids, and vitamins are mostly produced through aerobic fermentations, while products such as alcohols (ethanol, butanol, butanediol) are mainly produced through anaerobic fermentation (1-3). Organic acids such as lactic acid and succinic acid are also produced through anaerobic fermentation because higher yields could be obtained (4,5).During anaerobic fermentation, the reducing power is directed mostly to producing synthesis rather than to oxidization, resulting in a higher yield of target products. In addition, the low energy level due to the absence of oxidative phosphorylation often leads to a higher glycolysis rate, resulting in higher productivity (6).…”

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Reexamination of the Physiological Role of PykA in Escherichia coli Revealed that It Negatively Regulates the Intracellular ATP Levels under Anaerobic Conditions

Zhao

Dong

et al. 2017

Appl Environ Microbiol

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Pyruvate kinase is one of the three rate-limiting glycolytic enzymes that catalyze the last step of glycolysis, conversion of phosphoenolpyruvate (PEP) into pyruvate, which is associated with ATP generation. Two isozymes of pyruvate kinase, PykF and PykA, are identified in Escherichia coli. PykF is considered important, whereas PykA has a less-defined role. Prior studies inactivated the pykA gene to increase the level of its substrate, PEP, and thereby increased the yield of end products derived from PEP. We were surprised when we found a pykA::Tn5 mutant in a screen for increased yield of an end product derived from pyruvate (n-butanol), suggesting that the role of PykA needs to be reexamined. We show that the pykA mutant exhibited elevated intracellular ATP levels, biomass concentrations, glucose consumption, and n-butanol production. We also discovered that the pykA mutant expresses higher levels of a presumed pyruvate transporter, YhjX, permitting the mutant to recapture and metabolize excreted pyruvate. Furthermore, we demonstrated that the nucleotide diphosphate kinase activity of PykA leads to negative regulation of the intracellular ATP levels. Taking the data together, we propose that inactivation of pykA can be considered a general strategy to enhance the production of pyruvate-derived metabolites under anaerobic conditions. IMPORTANCE This study showed that knocking out pykA significantly increased the intracellular ATP level and thus significantly increased the levels of glucose consumption, biomass formation, and pyruvate-derived product formation under anaerobic conditions. pykA was considered to be encoding a dispensable pyruvate kinase; here we show that pykA negatively regulates the anaerobic glycolysis rate through regulating the energy distribution. Thus, knocking out pykA can be used as a general strategy to increase the level of pyruvate-derived fermentative products.KEYWORDS ATP, anaerobic condition, Escherichia coli, physiological role, PykA I ndustrial fermentation aims to produce valuable products from cheap feedstocks by utilizing the diverse functions of microbes. Products such as antibiotics, amino acids, and vitamins are mostly produced through aerobic fermentations, while products such as alcohols (ethanol, butanol, butanediol) are mainly produced through anaerobic fermentation (1-3). Organic acids such as lactic acid and succinic acid are also produced through anaerobic fermentation because higher yields could be obtained (4,5).During anaerobic fermentation, the reducing power is directed mostly to producing synthesis rather than to oxidization, resulting in a higher yield of target products. In addition, the low energy level due to the absence of oxidative phosphorylation often leads to a higher glycolysis rate, resulting in higher productivity (6). However, as the available ATP in anaerobic fermentation can be generated only from substrate-level phosphorylation, the biomass concentration in anaerobic fermentation is usually much

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Reexamination of the Physiological Role of PykA in Escherichia coli Revealed that It Negatively Regulates the Intracellular ATP Levels under Anaerobic Conditions

Zhao

Dong

et al. 2017

Appl Environ Microbiol

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“…B iological synthesis has emerged as a highly promising alternative to traditional organic synthesis for a variety of chemical compounds 1,2 . One such compound, 3-hydroxyg-butyrolactone (3HBL), is widely used in the pharmaceutical industry as a chiral building block for the statin class of cholesterol-reducing drugs such as Crestor and Lipitor, as well as the antibiotic Zyvox, and the antihyperlipidemic medication Zetia 3 .…”

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A platform pathway for production of 3-hydroxyacids provides a biosynthetic route to 3-hydroxy-γ-butyrolactone

et al. 2013

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The replacement of petroleum feedstocks with biomass to produce platform chemicals requires the development of appropriate conversion technologies. 3-Hydroxy-g-butyrolactone has been identified as one such chemical; however, there are no naturally occurring biosynthetic pathways for this molecule or its hydrolyzed form, 3,4-dihydroxybutyric acid. Here we design a novel pathway to produce various chiral 3-hydroxyacids, including 3,4-dihydroxybutyric acid, consisting of enzymes that condense two acyl-CoAs, stereospecifically reduce the resulting b-ketone and hydrolyze the CoA thioester to release the free acid. Acetyl-CoA serves as one substrate for the condensation reaction, whereas the second is produced intracellularly by a pathway enzyme that converts exogenously supplied organic acids. Feeding of butyrate, isobutyrate and glycolate results in the production of 3-hydroxyhexanoate, 3-hydroxy-4-methylvalerate and 3,4-dihydroxybutyric acid þ 3-hydroxy-gbutyrolactone, respectively, molecules with potential uses in applications from materials to medicines. We also unexpectedly observe the condensation reaction resulting in the production of the 2,3-dihydroxybutyric acid isomer, a potential value-added monomer.

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“…In addition, our result was far from the yield of succinic acid produced by various microorganisms. 56) For example, succinic acid yields in the metabolically engineered E. coli, C. glutamicum, A. succinogenes, and M. succiniciproducens were achieved at more than 50% (C-mol per C-mol glucose consumed). Therefore, further improvement of succinic acid production by S. cerevisiae is required.…”

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Metabolic engineering of Saccharomyces cerevisiae to improve succinic acid production based on metabolic profiling

Ito

Hirasawa

Shimizu

2014

Bioscience, Biotechnology, and Biochemistry

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We performed metabolic engineering on the budding yeast Saccharomyces cerevisiae for enhanced production of succinic acid. Aerobic succinic acid production in S. cerevisiae was achieved by disrupting the SDH1 and SDH2 genes, which encode the catalytic subunits of succinic acid dehydrogenase. Increased succinic acid production was achieved by eliminating the ethanol biosynthesis pathways. Metabolic profiling analysis revealed that succinic acid accumulated intracellularly following disruption of the SDH1 and SDH2 genes, which suggests that enhancing the export of intracellular succinic acid outside of cells increases succinic acid production in S. cerevisiae. The mae1 gene encoding the Schizosaccharomyces pombe malic acid transporter was introduced into S. cerevisiae, and as a result, succinic acid production was successfully improved. Metabolic profiling analysis is useful in producing chemicals for metabolic engineering of microorganisms.

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Microbial production of building block chemicals and polymers

Cited by 205 publications

References 53 publications

Reexamination of the Physiological Role of PykA in Escherichia coli Revealed that It Negatively Regulates the Intracellular ATP Levels under Anaerobic Conditions

Reexamination of the Physiological Role of PykA in Escherichia coli Revealed that It Negatively Regulates the Intracellular ATP Levels under Anaerobic Conditions

A platform pathway for production of 3-hydroxyacids provides a biosynthetic route to 3-hydroxy-γ-butyrolactone

Metabolic engineering of Saccharomyces cerevisiae to improve succinic acid production based on metabolic profiling

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