Expression of Galactose Permease and Pyruvate Carboxylase in Escherichia coli ptsG Mutant Increases the Growth Rate and Succinate Yield under Anaerobic Conditions

2006 ◽  
Vol 28 (2) ◽  
pp. 89-93 ◽  
Author(s):  
Qingzhao Wang ◽  
Chanyuan Wu ◽  
Tao Chen ◽  
Xun Chen ◽  
Xueming Zhao
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Pyruvate Carboxylase ◽  
Anaerobic Conditions

scholarly journals Effects of Growth Mode and Pyruvate Carboxylase on Succinic Acid Production by Metabolically Engineered Strains of Escherichia coli

2002 ◽  
Vol 68 (4) ◽  
pp. 1715-1727 ◽  
Author(s):  
G. N. Vemuri ◽  
M. A. Eiteman ◽  
E. Altman
Keyword(s):  
Escherichia Coli ◽  
Succinic Acid ◽  
Pyruvate Carboxylase ◽  
Isocitrate Lyase ◽  
Tricarboxylic Acid Cycle ◽  
Metabolic Flexibility ◽  
Dual Phase ◽  
Anaerobic Conditions ◽  
Carboxylase Activity ◽  
Lyase Activity

ABSTRACT Escherichia coli NZN111, which lacks activities for pyruvate-formate lyase and lactate dehydrogenase, and AFP111, a derivative which contains an additional mutation in ptsG (a gene encoding an enzyme of the glucose phophotransferase system), accumulate significant levels of succinic acid (succinate) under anaerobic conditions. Plasmid pTrc99A-pyc, which expresses the Rhizobium etli pyruvate carboxylase enzyme, was introduced into both strains. We compared growth, substrate consumption, product formation, and activities of seven key enzymes (acetate kinase, fumarate reductase, glucokinase, isocitrate dehydrogenase, isocitrate lyase, phosphoenolpyruvate carboxylase, and pyruvate carboxylase) from glucose for NZN111, NZN111/pTrc99A-pyc, AFP111, and AFP111/pTrc99A-pyc under both exclusively anaerobic and dual-phase conditions (an aerobic growth phase followed by an anaerobic production phase). The highest succinate mass yield was attained with AFP111/pTrc99A-pyc under dual-phase conditions with low pyruvate carboxylase activity. Dual-phase conditions led to significant isocitrate lyase activity in both NZN111 and AFP111, while under exclusively anaerobic conditions, an absence of isocitrate lyase activity resulted in significant pyruvate accumulation. Enzyme assays indicated that under dual-phase conditions, carbon flows not only through the reductive arm of the tricarboxylic acid cycle for succinate generation but also through the glyoxylate shunt and thus provides the cells with metabolic flexibility in the formation of succinate. Significant glucokinase activity in AFP111 compared to NZN111 similarly permits increased metabolic flexibility of AFP111. The differences between the strains and the benefit of pyruvate carboxylase under both exclusively anaerobic and dual-phase conditions are discussed in light of the cellular constraint for a redox balance.

scholarly journals Postantibiotic Effect and Delay of Regrowth in Strains Carrying Mutations That Save Proteins or RNA

2002 ◽  
Vol 46 (12) ◽  
pp. 4022-4025 ◽  
Author(s):  
Marzia Dolcino ◽  
Alberto Zoratti ◽  
Eugenio A. Debbia ◽  
Gian Carlo Schito ◽  
Anna Marchese
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Nalidixic Acid ◽  
Postantibiotic Effect ◽  
Anaerobic Conditions ◽  
E Coli

ABSTRACT The postantibiotic effect (PAE) values found for proteinase-defective (Lon−) Escherichia coli and RNase-defective E. coli exposed to antibiotics were reduced (31 to 60% and 35 to 50%, respectively) in comparison with the control (AB1157), and in the recA13 mutant these values were about 0.4 h with all drugs. Nalidixic acid, under anaerobic conditions, induced no PAE (0 to 0.1 h) in AB1157. A delay in regrowth (0.2 to 0.26 h) was noted with dnaA46(Ts), gyrA43(Ts), and gyrB41(Ts) mutants cultured for 2 h at 43°C. These findings suggest that when proteins and RNA are saved, the cell rapidly resumes the original growth rate.

Potentiation by L-cysteine of the bactericidal effect of hydrogen peroxide in Escherichia coli

1982 ◽  
Vol 152 (1) ◽  
pp. 81-88
Author(s):  
E H Berglin ◽  
M B Edlund ◽  
G K Nyberg ◽  
J Carlsson
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Metal Ion ◽  
Chelating Agent ◽  
Fold Increase ◽  
Bactericidal Effect ◽  
Anaerobic Conditions ◽  
Dna Breakage ◽  
E Coli ◽  
K 12

Under anaerobic conditions an exponentially growing culture of Escherichia coli K-12 was exposed to hydrogen peroxide in the presence of various compounds. Hydrogen peroxide (0.1 mM) together with 0.1 mM L-cysteine or L-cystine killed the organisms more rapidly than 10 mM hydrogen peroxide alone. The exposure of E. coli to hydrogen peroxide in the presence of L-cysteine inhibited some of the catalase. This inhibition, however, could not fully explain the 100-fold increase in hydrogen peroxide sensitivity of the organism in the presence of L-cysteine. Of other compounds tested only some thiols potentiated the bactericidal effect of hydrogen peroxide. These thiols were effective, however, only at concentrations significantly higher than 0.1 mM. The effect of L-cysteine and L-cystine could be annihilated by the metal ion chelating agent 2,2'-bipyridyl. DNA breakage in E. coli K-12 was demonstrated under conditions where the organisms were killed by hydrogen peroxide.

scholarly journals Role of growth rate on the orientational alignment of Escherichia coli in a slit

2017 ◽  
Vol 4 (6) ◽  
pp. 170463 ◽  
Author(s):  
Julian Sheats ◽  
Bianca Sclavi ◽  
Marco Cosentino Lagomarsino ◽  
Pietro Cicuta ◽  
Kevin D. Dorfman
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Aspect Ratio ◽  
Density Fluctuations ◽  
Global Alignment ◽  
Similar Amount ◽  
Cell Area ◽  
Nematic Ordering ◽  
Side Walls

We present experimental data on the nematic alignment of Escherichia coli bacteria confined in a slit, with an emphasis on the effect of growth rate and corresponding changes in cell aspect ratio. Global alignment with the channel walls arises from the combination of local nematic ordering of nearby cells, induced by cell division and the elongated shape of the cells, and the preferential orientation of cells proximate to the side walls of the slit. Decreasing the growth rate leads to a decrease in alignment with the walls, which is attributed primarily to effects of changing cell aspect ratio rather than changes in the variance in cell area. Decreasing confinement also reduces the degree of alignment by a similar amount as a decrease in the growth rate, but the distribution of the degree of alignment differs. The onset of alignment with the channel walls is coincident with the slits reaching their steady-state occupancy and connected to the re-orientation of locally aligned regions with respect to the walls during density fluctuations.

Growth-rate dependent regulation of mRNA stability in Escherichia coli

Nature ◽  
1984 ◽  
Vol 312 (5989) ◽  
pp. 75-77 ◽  
Author(s):  
G. Nilsson ◽  
J. G. Belasco ◽  
S. N. Cohen ◽  
A. von Gabain
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Mrna Stability ◽  
Rate Dependent

scholarly journals Escherichia colipopulations adapt to complex, unpredictable fluctuations without any trade-offs across environments

2016 ◽  
Author(s):  
Shraddha Karve ◽  
Devika Bhave ◽  
Dhanashri Nevgi ◽  
Sutirth Dey
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Growth Rates ◽  
Complex Environments ◽  
Multiple Stresses ◽  
Trade Off ◽  
Trade Offs ◽  
Fluctuating Environments ◽  
Laboratory Populations ◽  
Lower Variation

AbstractIn nature, organisms are simultaneously exposed to multiple stresses (i.e. complex environments) that often fluctuate unpredictably. While both these factors have been studied in isolation, the interaction of the two remains poorly explored. To address this issue, we selected laboratory populations ofEscherichia coliunder complex (i.e. stressful combinations of pH, H2O2and NaCl) unpredictably fluctuating environments for ~900 generations. We compared the growth rates and the corresponding trade-off patterns of these populations to those that were selected under constant values of the component stresses (i.e. pH, H2O2and NaCl) for the same duration. The fluctuation-selected populations had greater mean growth rate and lower variation for growth rate over all the selection environments experienced. However, while the populations selected under constant stresses experienced severe tradeoffs in many of the environments other than those in which they were selected, the fluctuation-selected populations could by-pass the across-environment trade-offs completely. Interestingly, trade-offs were found between growth rates and carrying capacities. The results suggest that complexity and fluctuations can strongly affect the underlying trade-off structure in evolving populations.

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