Model for oxygen transfer in a shake flask

Suijdam, J. C. van; Kossen, N. W. F.; Joha, A. C.

doi:10.1002/bit.260201102

Cited by 84 publications

(51 citation statements)

References 13 publications

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“…) from previous reports on gas-liquid mass transfer in shake flask systems (26,44) and further confirmed by in-vessel measurements conducted by a conventional dynamic gassing-out technique as previously described (9).…”

supporting

confidence: 80%

Escherichia coli Strains Engineered for Homofermentative Production of d -Lactic Acid from Glycerol

Mazumdar

Clomburg

González

2010

Appl Environ Microbiol

145

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Given its availability and low price, glycerol has become an ideal feedstock for the production of fuels and chemicals. We recently reported the pathways mediating the metabolism of glycerol in Escherichia coli under anaerobic and microaerobic conditions. In this work, we engineer E. coli for the efficient conversion of glycerol to D-lactic acid (D-lactate), a negligible product of glycerol metabolism in wild-type strains. A homofermentative route for D-lactate production was engineered by overexpressing pathways involved in the conversion of glycerol to this product and blocking those leading to the synthesis of competing by-products. The former included the overexpression of the enzymes involved in the conversion of glycerol to glycolytic intermediates (GlpK-GlpD and GldA-DHAK pathways) and the synthesis of D-lactate from pyruvate (D-lactate dehydrogenase). On the other hand, the synthesis of succinate, acetate, and ethanol was minimized through two strategies: (i) inactivation of pyruvate-formate lyase (⌬pflB) and fumarate reductase (⌬frdA) (strain LA01) and (ii) inactivation of fumarate reductase (⌬frdA), phosphate acetyltransferase (⌬pta), and alcohol/acetaldehyde dehydrogenase (⌬adhE) (strain LA02). A mutation that blocked the aerobic D-lactate dehydrogenase (⌬dld) also was introduced in both LA01 and LA02 to prevent the utilization of D-lactate. The most efficient strain (LA02⌬dld, with GlpK-GlpD overexpressed) produced 32 g/liter of D-lactate from 40 g/liter of glycerol at a yield of 85% of the theoretical maximum and with a chiral purity higher than 99.9%. This strain exhibited maximum volumetric and specific productivities for D-lactate production of 1.5 g/liter/h and 1.25 g/g cell mass/h, respectively. The engineered homolactic route generates 1 to 2 mol of ATP per mol of D-lactate and is redox balanced, thus representing a viable metabolic pathway.

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supporting

confidence: 80%

Escherichia coli Strains Engineered for Homofermentative Production of d -Lactic Acid from Glycerol

Mazumdar

Clomburg

González

2010

Appl Environ Microbiol

145

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“…MOPS minimal medium (41) supplemented with 0.5% (wt/vol) palmitic acid and 0.2% (wt/vol) Brij 58 (Fluka Chemie AG, Buchs, Switzerland) was used. The oxygen transfer rate (k L a) was estimated from previous reports on gas-liquid mass transfer in shake flask systems (37,63) and further confirmed by in-vessel measurements conducted by the conventional dynamic gassing-out technique (14).…”

supporting

confidence: 53%

Engineered Respiro-Fermentative Metabolism for the Production of Biofuels and Biochemicals from Fatty Acid-Rich Feedstocks

Dellomonaco

Rivera²,

Campbell³

et al. 2010

Appl Environ Microbiol

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Although lignocellulosic sugars have been proposed as the primary feedstock for the biological production of renewable fuels and chemicals, the availability of fatty acid (FA)-rich feedstocks and recent progress in the development of oil-accumulating organisms make FAs an attractive alternative. In addition to their abundance, the metabolism of FAs is very efficient and could support product yields significantly higher than those obtained from lignocellulosic sugars. However, FAs are metabolized only under respiratory conditions, a metabolic mode that does not support the synthesis of fermentation products. In the work reported here we engineered several native and heterologous fermentative pathways to function in Escherichia coli under aerobic conditions, thus creating a respiro-fermentative metabolic mode that enables the efficient synthesis of fuels and chemicals from FAs. Representative biofuels (ethanol and butanol) and biochemicals (acetate, acetone, isopropanol, succinate, and propionate) were chosen as target products to illustrate the feasibility of the proposed platform. The yields of ethanol, acetate, and acetone in the engineered strains exceeded those reported in the literature for their production from sugars, and in the cases of ethanol and acetate they also surpassed the maximum theoretical values that can be achieved from lignocellulosic sugars. Butanol was produced at yields and titers that were between 2-and 3-fold higher than those reported for its production from sugars in previously engineered microorganisms. Moreover, our work demonstrates production of propionate, a compound previously thought to be synthesized only by propionibacteria, in E. coli. Finally, the synthesis of isopropanol and succinate was also demonstrated. The work reported here represents the first effort toward engineering microorganisms for the conversion of FAs to the aforementioned products.

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“…The possibility that, besides the growth phase, the variation of oxygen concentration during growth also affected gene expression should not be disregarded. Although there is always some oxygen present during growth (Van Suijdam et al, 1978), it is likely that growth at the later stages of growth (MS and LS) is limited by the oxygen supply. The transcription level variation of sdhA, cyoB and cydA genes during growth did not follow the trend described for progressive oxygen concentration decrease reported by Rolfe et al (2011).…”

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confidence: 99%