Selection for cell yield does not reduce overflow metabolism in E. coli

Overflow metabolism is ubiquitous in nature, and it is often considered inefficient because it leads to a relatively low biomass yield per consumed carbon. This metabolic strategy has been described as advantageous because it supports high growth rates during nutrient competition. Here we experimentally evolved bacteria without nutrient competition by repeatedly growing and mixing millions of parallel batch cultures of E. coli. Each culture originated from a water-in-oil emulsion droplet seeded with a single cell. Unexpectedly we found that overflow metabolism (acetate production) did not change. Instead the numerical cell yield during the consumption of the accumulated acetate increased as a consequence of a reduction in cell size. Our experiments and a mathematical model show that fast growth and overflow metabolism followed by the consumption of the overflow metabolite, leads to a higher numerical cell yield and therefore a higher fitness compared to full respiration of the substrate. This provides an evolutionary scenario where overflow metabolism can be favourable even in the absence of nutrient competition.

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High Kanamycin Concentration as Another Stress Factor Additional to Temperature to Increase pDNA Production in E. coli DH5α Batch and Fed-Batch Cultures

Microorganisms ◽

10.3390/microorganisms7120711 ◽

2019 ◽

Vol 7 (12) ◽

pp. 711

Author(s):

Fernando Grijalva-Hernández ◽

Jesús Vega-Estrada ◽

Montserrat Escobar-Rosales ◽

Jaime Ortega-López ◽

Ricardo Aguilar-López ◽

...

Keyword(s):

Morphological Changes ◽

Growth Conditions ◽

Medium Composition ◽

High Cell Density Culture ◽

Overflow Metabolism ◽

Fed Batch ◽

Batch Cultures ◽

E Coli ◽

Metabolic Burden ◽

Kanamycin Concentration

Plasmid DNA (pDNA) vaccines require high supercoiled-pDNA doses (milligrams) to achieve an adequate immune response. Therefore, processes development to obtain high pDNA yields and productivity is crucial. pDNA production is affected by several factors including culture type, medium composition, and growth conditions. We evaluated the effect of kanamycin concentration and temperature on pDNA production, overflow metabolism (organic acids) and metabolic burden (neomycin phosphotransferase II) in batch and fed-batch cultures of Escherichia coli DH5α-pVAX1-NH36. Results indicated that high kanamycin concentration increases the volumetric productivity, volumetric and specific yields of pDNA when batch cultures were carried out at 42 °C, and overflow metabolism reduced but metabolic burden increased. Micrographs taken with a scanning electron microscope (SEM) were analyzed, showing important morphological changes. The high kanamycin concentration (300 mg/L) was evaluated in high cell density culture (50 gDCW/L), which was reached using a fed-batch culture with temperature increase by controlling heating and growth rates. The pDNA volumetric yield and productivity were 759 mg/L and 31.19 mg/L/h, respectively, two-fold greater than the control with a kanamycin concentration of 50 mg/L. A stress-based process simultaneously caused by temperature and high kanamycin concentration can be successfully applied to increase pDNA production.

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Generic Model Control Applied to E. coli BL21(DE3) Fed-Batch Cultures

Processes ◽

10.3390/pr8070772 ◽

2020 ◽

Vol 8 (7) ◽

pp. 772 ◽

Cited By ~ 1

Author(s):

Merouane Abadli ◽

Laurent Dewasme ◽

Sihem Tebbani ◽

Didier Dumur ◽

Alain Vande Wouwer

Keyword(s):

Mechanistic Model ◽

Biomass Concentration ◽

Generic Model ◽

Control Law ◽

Overflow Metabolism ◽

Fed Batch ◽

Batch Cultures ◽

E Coli ◽

Model Control ◽

Generic Model Control

This work proposes a Generic Model Control (GMC) strategy to regulate biomass growth in fed-batch cultures of Escherichia coli BL21(DE3). The control law is established using a previously validated mechanistic model based on the overflow metabolism paradigm. A model reduction is carried out to prevent the controller from relying on kinetics, which may be uncertain. In order to limit the controller to the use of a single measurement, i.e., biomass concentration which is readily available, a Kalman filter is designed to reconstruct the nonmeasurable information from the outlet gas and the remaining stoichiometry. Several numerical simulations are presented to assess the controller robustness with respect to model uncertainty. Experimental validation of the proposed GMC strategy is achieved with a lab-scale bioreactor.

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Deemulsification of Water-in-Oil Emulsion with Sludges

Water Quality Research Journal ◽

10.2166/wqrj.1987.034 ◽

1987 ◽

Vol 22 (3) ◽

pp. 437-443 ◽

Cited By ~ 5

Author(s):

N. Kosaric ◽

Z. Duvnjak

Keyword(s):

Activated Sludge ◽

Room Temperature ◽

Petroleum Refinery ◽

Treatment Plant ◽

Granular Sludge ◽

Activated Sludge Process ◽

Sludge Treatment ◽

Oil Emulsion ◽

Water In Oil Emulsion ◽

Aerobic Sludge

Abstract Aerobic sludge from a municipal activated sludge treatment plant, sludge from a conventional municipal anaerobic digester, aerobic sludge from an activated sludge process of a petroleum refinery, and granular sludge from an upflow sludge blanket reactor (USBR) were tested in the deemulsification of a water-in-oil emulsion. All sludges except the last one, showed a good deemulsification capability and could he used for a partial deemulsification of such emulsions. The rate and degree of the deemulsifications increased with an increase in sludge concentrations. The deemulsifications were faster at 85°C and required smaller amounts of sludge than in the case of the deemulsifications at room temperature. An extended stirring (up to a certain limit) in the course of the dispersion of sludge emulsion helped the deemulsification. Too vigorous agitation had an adverse effect. The deemulsification effect of sludge became less visible with an increase in the dilution of emulsion which caused an increase in its spontaneous deemulsification.

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Destruction of water-in-oil emulsions in electromagnetic fields in a dynamic mode

Proceedings of the Mavlyutov Institute of Mechanics ◽

10.21662/uim2012.1.021 ◽

2012 ◽

Vol 9 (1) ◽

pp. 110-115

Author(s):

L.A. Kovaleva ◽

R.R. Zinnatullin ◽

V.N. Blagochinnov ◽

A.A. Musin ◽

Yu.I. Fatkhullina ◽

...

Keyword(s):

Dielectric Properties ◽

Radio Frequency ◽

Electromagnetic Fields ◽

Dynamic Mode ◽

Droplet Dynamics ◽

Oil Emulsion ◽

Numerical Studies ◽

Em Field ◽

Oil Emulsions ◽

Water In Oil Emulsion

Some results of experimental and numerical studies of the influence of radio-frequency (RF) and microwave (MW) electromagnetic (EM) fields on water-in-oil emulsions are presented. A detailed investigation of the dependence of the dielectric properties of emulsions on the frequency of the field makes it possible to establish the most effective frequency range of the EM influence. The results of water-in-oil emulsion stability in the RF EM field depending on their dielectric properties are presented. The effect of the MW EM field on the emulsion in a dynamic mode has been studied experimentally. In an attempt to understand the mechanism of emulsion destruction the mathematical model for a single emulsion droplet dynamics in radio-frequency (RF) and microwave (MW) electromagnetic fields is formulated.

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Selective and ultrafast agglomeration of chalcopyrite by a water in oil emulsion binder

Minerals Engineering ◽

10.1016/j.mineng.2021.106900 ◽

2021 ◽

Vol 167 ◽

pp. 106900

Author(s):

G. Sahasrabudhe ◽

G. DeIuliis ◽

J. Davy ◽

K.P. Galvin

Keyword(s):

Oil Emulsion ◽

Water In Oil Emulsion

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Combination of electric field and medium coalescence for enhanced demulsification of water-in-oil emulsion

Chemical Engineering Science ◽

10.1016/j.ces.2021.116680 ◽

2021 ◽

pp. 116680

Author(s):

Hao Lu ◽

Shihan Wu ◽

Zhiqiang Miao ◽

Xiao Xu ◽

Yiqian Liu ◽

...

Keyword(s):

Electric Field ◽

Oil Emulsion ◽

Water In Oil Emulsion

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Mechanisms on the stability and instability of water-in-oil emulsion stabilized by interfacially active asphaltenes: Role of hydrogen bonding reconstructing

Fuel ◽

10.1016/j.fuel.2021.120763 ◽

2021 ◽

Vol 297 ◽

pp. 120763

Author(s):

Jun Ma ◽

Yongli Yang ◽

Xingang Li ◽

Hong Sui ◽

Lin He

Keyword(s):

Hydrogen Bonding ◽

Oil Emulsion ◽

Stability And Instability ◽

The Stability ◽

Water In Oil Emulsion

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Influence of Genetic Selection for Growth and Broodstock Diet n-3 LC-PUFA Levels on Reproductive Performance of Gilthead Seabream, Sparus aurata

Animals ◽

10.3390/ani11020519 ◽

2021 ◽

Vol 11 (2) ◽

pp. 519

Author(s):

Shajahan Ferosekhan ◽

Serhat Turkmen ◽

Cathaysa Pérez-García ◽

Hanlin Xu ◽

Ana Gómez ◽

...

Keyword(s):

Reproductive Performance ◽

Egg Quality ◽

Sparus Aurata ◽

Genetic Selection ◽

Growth Trait ◽

High Growth ◽

Gilthead Seabream ◽

Commercial Diet ◽

Selection For ◽

Broodstock Diet

Genetic selection in gilthead seabream (GSB), Sparus aurata, has been undertaken to improve the growth, feed efficiency, fillet quality, skeletal deformities and disease resistance, but no study is available to delineate the effect of genetic selection for growth trait on GSB reproductive performance under mass spawning condition. In this study, high growth (HG) or low growth (LG) GSB broodstock were selected to evaluate the sex steroid hormones, sperm, egg quality and reproductive performance under different feeding regime of commercial diet or experimental broodstock diet containing either fish oil (FO) or vegetable oil (VO) based diet. Under commercial diet feeding phase, broodstock selected for either high growth or low growth did not show any significant changes in the egg production per kg female whereas egg viability percentage was positively (p = 0.014) improved by the high growth trait broodstock group. The experimental diet feeding results revealed that both growth trait and dietary fatty acid composition influenced the reproductive performance of GSB broodstock. In the experimental diet feeding phase, we observed high growth trait GSB males produced a higher number of sperm cells (p < 0.001) and also showed a higher sperm motility (p = 0.048) percentage. The viable egg and larval production per spawn per kg female were significantly improved by the broodstock selected for high growth trait and fed with fish oil-based diet. This present study results signifies that gilthead seabream broodstock selected on growth trait could have positive role in improvement of sperm and egg quality to produce viable progeny.

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