scholarly journals Metabolic regulation of <i>Escherichia coli</i> cultivated under anaerobic and aerobic conditions in response to the specific pathway gene knockouts

2013 ◽  
Vol 04 (03) ◽  
pp. 455-468 ◽  
Author(s):  
Yu Matsuoka ◽  
Kazuyuki Shimizu
Keyword(s):  
Escherichia Coli ◽  
Metabolic Regulation ◽  
Aerobic Conditions ◽  
Pathway Gene ◽  
Gene Knockouts ◽  
Specific Pathway

scholarly journals Microbiology of brewing production - bacteria of the order Enterobacterales and culture methods for their detection

2020 ◽  
Vol 66 (5) ◽  
pp. 345-350
Author(s):  
Petra Kubizniaková ◽  
Martina Brožová ◽  
Kateřina Štulíková ◽  
Eva Vontrobová ◽  
Katarína Hanzalíková ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Serratia Marcescens ◽  
Klebsiella Oxytoca ◽  
Enterobacter Cloacae ◽  
Citrobacter Freundii ◽  
Culture Methods ◽  
Aerobic Conditions ◽  
Rahnella Aquatilis ◽  
Raoultella Terrigena ◽  
Incubation Temperatures

The growth of 7 strains belonging to the order of Enterobacterales, represented by the species of Citrobacter Freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Obesumbacterium proteus, Rahnella aquatilis, Raoultella terrigena, Serratia marcescens and Shimwellia pseudoproteus, was monitored on selected cultivation media. Three types of agars - Endo, MacConkey and Chromocult Coliform agar together with two incubation temperatures of 28 and 37 °C were tested under aerobic conditions. The aim of the study was to detect such essential enterobacteria harmful to beer that cannot be proven at 37 °C, which is the temperature usually used in operational laboratories in breweries. Our results showed that most of the tested strains of enterobacteria were able to grow at 28 °C on all selected types of agar. The exception was just the representatives detection of which is problematic at 37 °C. Nevertheless, a little or no growth was always observed on just one of the tested media.

DYNAMIC ASPECTS OF CASCADE-TYPE METABOLIC REGULATION

1995 ◽  
Vol 03 (01) ◽  
pp. 187-196 ◽  
Author(s):  
DOUWE MOLENAAR ◽  
BORIS N. KHOLODENKO ◽  
WALLY C. VAN HEESWIJK ◽  
HANS V. WESTERHOFF
Keyword(s):  
Escherichia Coli ◽  
Glutamine Synthetase ◽  
Metabolic Regulation ◽  
Growth Conditions ◽  
Covalent Modification ◽  
Physiological Signals ◽  
Slow Dynamics ◽  
Evolutionary Advantage ◽  
Ammonia Fixation ◽  
Cascade Type

Cascade-type regulation, where certain enzymes in response to physiological signals modify the activity of other enzymes by covalent modification, is found in many organisms. We study the covalent regulation of glutamine synthetase which is involved in ammonia fixation in the bacterium Escherichia coli. In this paper we pose the question whether this type of regulation of glutamine synthetase has, under certain growth conditions an advantage over other types of regulation, e.g., allosteric regulation. We propose that the relatively slow dynamics of cascade-type regulation has an evolutionary advantage under conditions of fluctuating ammonia concentrations.

scholarly journals In vivo cycling of the Escherichia coli transcription factor FNR between active and inactive states

Microbiology ◽  
2005 ◽  
Vol 151 (12) ◽  
pp. 4063-4070 ◽  
Author(s):  
David P. Dibden ◽  
Jeffrey Green
Keyword(s):  
Escherichia Coli ◽  
De Novo ◽  
Oxygen Availability ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Fnr Protein ◽  
Transcription Regulators ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

FNR proteins are transcription regulators that sense changes in oxygen availability via assembly–disassembly of [4Fe–4S] clusters. The Escherichia coli FNR protein is present in bacteria grown under aerobic and anaerobic conditions. Under aerobic conditions, FNR is isolated as an inactive monomeric apoprotein, whereas under anaerobic conditions, FNR is present as an active dimeric holoprotein containing one [4Fe–4S] cluster per subunit. It has been suggested that the active and inactive forms of FNR are interconverted in vivo, or that iron–sulphur clusters are mostly incorporated into newly synthesized FNR. Here, experiments using a thermo-inducible fnr expression plasmid showed that a model FNR-dependent promoter is activated under anaerobic conditions by FNR that was synthesized under aerobic conditions. Immunoblots suggested that FNR was more prone to degradation under aerobic compared with anaerobic conditions, and that the ClpXP protease contributes to this degradation. Nevertheless, FNR was sufficiently long lived (half-life under aerobic conditions, ∼45 min) to allow cycling between active and inactive forms. Measuring the abundance of the FNR-activated dms transcript when chloramphenicol-treated cultures were switched between aerobic and anaerobic conditions showed that it increased when cultures were switched to anaerobic conditions, and decreased when aerobic conditions were restored. In contrast, measurement of the abundance of the FNR-repressed ndh transcript under the same conditions showed that it decreased upon switching to anaerobic conditions, and then increased when aerobic conditions were restored. The abundance of the FNR- and oxygen-independent tatE transcript was unaffected by changes in oxygen availability. Thus, the simplest explanation for the observations reported here is that the FNR protein can be switched between inactive and active forms in vivo in the absence of de novo protein synthesis.

scholarly journals Metabolic regulation of Irp gene expression in Escherichia coli K-12

Microbiology ◽  
1997 ◽  
Vol 143 (6) ◽  
pp. 2079-2084 ◽  
Author(s):  
C. F. Chen ◽  
J. Lan ◽  
M. Korovine ◽  
Z. Q. Shao ◽  
L. Tao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Metabolic Regulation ◽  
Expression In Escherichia Coli ◽  
K 12

scholarly journals Effect of Exposure to Chlorhexidine Residues at “During Use” Concentrations on Antimicrobial Susceptibility Profile, Efflux, Conjugative Plasmid Transfer, and Metabolism of Escherichia coli

2020 ◽  
Vol 64 (12) ◽  
Author(s):  
R. Wesgate ◽  
S. Fanning ◽  
Y. Hu ◽  
J.-Y. Maillard
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Resistance ◽  
Antimicrobial Susceptibility ◽  
Metabolic Regulation ◽  
Conjugative Plasmid ◽  
Metabolic Phenotype ◽  
Cross Resistance ◽  
Content Type ◽  
Phenotypic Microarray ◽  
The Impact

ABSTRACT There is no standardized protocol to predict the concentration levels of microbicides that are left on surfaces as a result of the use of these products, and there is no standardized method to predict the potential risk that such levels pose to emerging antibacterial resistance. The ability to distinguish between selection and adaption processes for antimicrobial resistance in bacteria and the impact of different concentrations of microbicide exposure have not been fully investigated to date. This study considers the effect of exposure to a low concentration of chlorhexidine digluconate (CHX) on selected phenotypes of Escherichia coli and relates the findings to the risk of emerging antimicrobial resistance. A concentration of 0.006 mg/ml CHX is a realistic “during use” exposure concentration measured on surfaces. At this concentration, it was possible for CHX-susceptible bacteria to survive, adapt through metabolic alterations, exhibit a transient decrease in antimicrobial susceptibility, and express stable clinical cross-resistance to front-line antibiotics. Efflux activity was present naturally in tested isolates, and it increased in the presence of 0.00005 mg/ml CHX but ceased with 0.002 mg/ml CHX. Phenotypic microarray assays highlighted a difference in metabolic regulation at 0.00005 mg/ml and 0.002 mg/ml CHX; more changes occurred after growth with the latter concentration. Metabolic phenotype changes were observed for substrates involved with the metabolism of some amino acids, cofactors, and secondary metabolites. It was possible for one isolate to continue transferring ampicillin resistance in the presence of 0.00005 mg/ml CHX, whilst 0.002 mg/ml CHX prevented conjugative transfer. In conclusion, E. coli phenotype responses to CHX exposure are concentration dependent, with realistic residual CHX concentrations resulting in stable clinical cross-resistance to antibiotics.

Sign in / Sign up

Export Citation Format

Share Document