The Csr System Regulates
            <i>Escherichia coli</i>
            Fitness by Controlling Glycogen Accumulation and Energy Levels

Morin, Manon; Ropers, Delphine; Cinquemani, Eugenio; Portais, Jean‐Charles; Enjalbert, Brice; Cocaign‐Bousquet, Muriel

doi:10.1128/mbio.01628-17

Cited by 25 publications

(20 citation statements)

References 49 publications

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“…Most of the studies have focused on how glycogen metabolism-related genes influence E. coli growth rates and glycogen accumulation, rather than the impacts of culture medium [17,18,22]. Varik et al noticed the importance of culture composition and studied how amino acid composition could change E. coli growth rate and glycogen accumulation [18].…”

Section: Results and Discsussionmentioning

confidence: 99%

Optimized M9 Minimal Salts Medium for Enhanced Growth Rate and Glycogen Accumulation of Escherichia coli DH5��

Wang¹,

Liu²,

Du³

et al. 2018

Microbiology and Biotechnology Letters

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Glycogen plays important roles in bacteria. Its structure and storage capability have received more attention recently because of the potential correlations with environmental durability and pathogenicity. However, the low level of intracellular glycogen makes extraction and structure characterization difficult, inhibiting functional studies. Bacteria grown in regular media such as lysogeny broth and tryptic soy broth do no accumulate large amounts of glycogen. Comparative analyses of bacterial media reported in literature for glycogen-related studies revealed that there was no consistency in the recipes reported. Escherichia coli DH5α is a convenient model organism for gene manipulation studies with respect to glycogen. Additionally, M9 minimal salts medium is widely used to improve glycogen accumulation, although its composition varies. In this study, we optimized the M9 medium by adjusting the concentrations of itrogen source, tryptone, carbon source, and glucose, in order to achieve a balance between the growth rate and glycogen accumulation. Our result showed that 1 × M9 minimal salts medium containing 0.4% tryptone and 0.8% glucose was a well-balanced nutrient source for enhancing the growth and glycogen storage in bacteria. This result will help future investigations related to bacterial physiology in terms of glycogen function.

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Section: Results and Discsussionmentioning

confidence: 99%

Optimized M9 Minimal Salts Medium for Enhanced Growth Rate and Glycogen Accumulation of Escherichia coli DH5��

Wang¹,

Liu²,

Du³

et al. 2018

Microbiology and Biotechnology Letters

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“…When the substrate is in excess, some of the glycolytic flux is diverted in the production of glycogen by G1P. The cells can then use this storage to grow under substrate limitation [91]. An attempt to quantify intracellular glycogen was performed, leading only to the conclusion that glycogen levels were increased during feast-famine, compared to steady-state.…”

Section: Total Metabolomementioning

confidence: 99%

Escherichia coli metabolism under short-term repetitive substrate dynamics: adaptation and trade-offs

2020

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Background: Microbial metabolism is highly dependent on the environmental conditions. Especially, the substrate concentration, as well as oxygen availability, determine the metabolic rates. In large-scale bioreactors, microorganisms encounter dynamic conditions in substrate and oxygen availability (mixing limitations), which influence their metabolism and subsequently their physiology. Earlier, single substrate pulse experiments were not able to explain the observed physiological changes generated under large-scale industrial fermentation conditions. Results: In this study we applied a repetitive feast-famine regime in an aerobic Escherichia coli culture in a timescale of seconds. The regime was applied for several generations, allowing cells to adapt to the (repetitive) dynamic environment. The observed response was highly reproducible over the cycles, indicating that cells were indeed fully adapted to the regime. We observed an increase of the specific substrate and oxygen consumption (average) rates during the feast-famine regime, compared to a steady-state (chemostat) reference environment. The increased rates at same (average) growth rate led to a reduced biomass yield (30% lower). Interestingly, this drop was not followed by increased by-product formation, pointing to the existence of energy-spilling reactions. During the feast-famine cycle, the cells rapidly increased their uptake rate. Within 10 s after the beginning of the feeding, the substrate uptake rate was higher (4.68 μmol/g CDW /s) than reported during batch growth (3.3 μmol/g CDW /s). The high uptake led to an accumulation of several intracellular metabolites, during the feast phase, accounting for up to 34% of the carbon supplied. Although the metabolite concentrations changed rapidly, the cellular energy charge remained unaffected, suggesting well-controlled balance between ATP producing and ATP consuming reactions. Conclusions: The adaptation of the physiology and metabolism of E. coli under substrate dynamics, representative for large-scale fermenters, revealed the existence of several cellular mechanisms coping with stress. Changes in the substrate uptake system, storage potential and energy-spilling processes resulted to be of great importance. These metabolic strategies consist a meaningful step to further tackle reduced microbial performance, observed under large-scale cultivations.

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“…3a) and not only at the cell periphery as reported previously for E. coli [41][42][43] . This indicates that small amounts of glycogen remain within these cells upon exiting lag phase 44,45 , possibly due to structural changes that are known to increase short chains within this polymer 19,21,39 and which would be expected to delay turnover 39 .…”

Section: Discussionmentioning

confidence: 99%

Disruption of glycogen metabolism alters cell size inEscherichia coli

Walt¹,

Bürgy²,

Engelbrecht³

et al. 2020

Preprint

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The availability of nutrients impacts cell size and growth rate in many organisms. Research in E. coli has traditionally focused on the influence of exogenous nutrient sources on cell size through their effect on growth and cell cycle progression. Utilising a set of mutants where three genes involved in glycogen degradation -glycogen phosphorylase (glgP), glycogen debranching enzyme (glgX) and maltodextrin phosphorylase (malP) -were disrupted, we examined if endogenous polyglucan degradation affects cell size. It was found that mutations to malP increased cell lengths and resulted in substantial heterogeneity of cell size. This was most apparent during exponential growth and the phenotype was unaccompanied by alterations in Z-ring occurrence, cellular FtsZ levels and generation times. ∆malP mutant cells did, however, accumulate increased DnaA amounts at late growth stages indicating a potential effect on DNA replication. Replication run-out experiments demonstrated that this was indeed the case, and that DNA replication was also affected in the other mutants. Bacteria with a disruption in glgX accumulated glycogen and protein inclusion bodies that coincided with each other at inter-nucleoid and polar regions.Robust adaptive survival strategies are employed by bacteria to promote fitness. Most notably, when nutrients are abundant, bacterial cells demonstrate increases in length, width and growth rate 1 which permit parental cells to promote vigour of future generations by giving rise to larger daughter cells 2 . Enhanced rates of macromolecular biosynthesis accompany nutrientdependent size increases to ensure that larger cells are born with more DNA, RNA and protein 3-6 . This positive scaling relationship between cell size and external nutrient-imposed growth rate has historically been termed Schaechter's nutrient growth law 1 . Escherichia coli is known to passively correct deviant changes to cell size by adding a constant volume of cellular material (cell unit) between division events, regardless of size at birth 7,8 which has led to the proposal of what is known as the adder model 9 .Under steady-state conditions, the cell unit postulated in the adder model is dictated by two mechanisms 10 . The first is an initiation adder that ensures DNA origin firing is triggered only when the cell has grown and accumulated protein factors, such as DnaA, to a threshold required to initiate DNA replication. Synchronous origin firing under conditions of slow growth results in the birth of two daughters, each containing one parental chromosome; however, in environments that promote rapid growth, cell division can occur at a rate faster than the time it takes to duplicate the genome. Bacteria overcome this problem by initiating overlapping replication cycles, so daughter cells are born with two, four or even eight replication origins that ensure genomic integrity is maintained when the cell is faced with rapid division rates 11 . Several studies have reported that the volume of the cell unit proposed in the adder model is prop...

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The Csr System Regulates Escherichia coli Fitness by Controlling Glycogen Accumulation and Energy Levels

Cited by 25 publications

References 49 publications

Optimized M9 Minimal Salts Medium for Enhanced Growth Rate and Glycogen Accumulation of Escherichia coli DH5��

Optimized M9 Minimal Salts Medium for Enhanced Growth Rate and Glycogen Accumulation of Escherichia coli DH5��

Escherichia coli metabolism under short-term repetitive substrate dynamics: adaptation and trade-offs

Disruption of glycogen metabolism alters cell size inEscherichia coli

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