Inhibition of colicin production by fermentable sugars

1974 ◽  
Vol 20 (2) ◽  
pp. 269-272 ◽  
Author(s):  
M. Lavoie ◽  
L. G. Mathieu ◽  
L. Charron-Allie
Keyword(s):  
Escherichia Coli ◽  
Catabolite Repression ◽  
Indicator Strain ◽  
Shigella Sonnei ◽  
Nutrient Broth ◽  
Sensitive Indicator ◽  
Fermentable Sugars ◽  
Experimental Conditions ◽  
R Factor ◽  
Mixed Cultivation

Several fermentable sugars (glucose, lactose, arabinose, and to a lesser extent sucrose) were found to reduce colicin production in a strain of Shigella sonnei P9 (colicins E2 and I) and in a strain of Escherichia coli CA31 (colicin A). Inositol and adonitol, which are apparently not fermented by these colicinogenic strains, did not seem to affect colicin production under our experimental conditions. The results indicated that the production of colicins E2 and A, like the formation of certain R-factor-coded enzymes, may be subject to catabolite repression. A system of mixed cultivation in nutrient broth, of colicinogenic and sensitive strains, was also used; under these conditions, the number of viable units of the sensitive indicator strain decreased more rapidly in the absence than in the presence of added glucose.

scholarly journals Relaxation of catabolite repression in streptomycin-dependent Escherichia coli

1969 ◽  
Vol 111 (3) ◽  
pp. 279-286 ◽  
Author(s):  
M. B. Coukell ◽  
W. J. Polglase
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Catabolite Repression ◽  
Citrate Synthase ◽  
Wild Type ◽  
Experimental Conditions ◽  
E Coli ◽  
Equivalent Quantity ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Escherichia Coli B

Acetohydroxy acid synthetase, which is sensitive to catabolite repression in wild-type Escherichia coli B, was relatively resistant to this control in a streptomycin-dependent mutant. The streptomycin-dependent mutant was found to be inducible for β-galactosidase in the presence of glucose, although repression of β-galactosidase by glucose occurred under experimental conditions where growth of the streptomycin-dependent mutant was limited. Additional glucose-sensitive enzymes of wild-type E. coli B (citrate synthase, fumarase, aconitase and isocitrate dehydrogenase) were found to be insensitive to the carbon source in streptomycin-dependent mutants: these enzymes were formed by streptomycin-dependent E. coli B in equivalent quantities when either glucose or glycerol was the carbon source. Two enzymes, glucokinase and glucose 6-phosphate dehydrogenase, that are glucose-insensitive in wild-type E. coli B were formed in equivalent quantity on glucose or glycerol in both streptomycin-sensitive and streptomycin-dependent E. coli B. The results indicate a general decrease or relaxation of catabolite repression in the streptomycin-dependent mutant. The yield of streptomycin-dependent cells from glucose was one-third less than that of the streptomycin-sensitive strain. We conclude that the decreased efficiency of glucose utilization in streptomycin-dependent E. coli B is responsible for the relaxation of catabolite repression in this mutant.

Enzymatic reduction of mercurous and mercuric ions in Bacillus cereus

1981 ◽  
Vol 27 (2) ◽  
pp. 192-197 ◽  
Author(s):  
K. Izaki
Keyword(s):  
Escherichia Coli ◽  
Bacillus Cereus ◽  
Heavy Metal Ions ◽  
Heat Stability ◽  
Nutrient Broth ◽  
R Factor ◽  
Mercuric Ion ◽  
Enzymatic Reduction ◽  
Mercuric Ions ◽  
Sulfhydryl Compounds

A strain of Bacillus cereus, which can grow in nutrient broth containing 50 μM HgCl2, was isolated from soil. Mercurous or mercuric ion dependent oxidation of reduced NADPH was demonstrated in crude extracts of cells grown in nutrient broth containing 10 μM HgCl2. The properties of this mercuric reductase were similar to those of the enzymes from R factor bearing Escherichia coli in substrate specificity, heat stability, requirement of sulfhydryl compounds, sensitivity to some heavy metal ions, and molelcular weight.

scholarly journals Sulfaquinoxaline Oxidation and Toxicity Reduction by Photo-Fenton Process

2021 ◽  
Vol 18 (3) ◽  
pp. 1005
Author(s):  
Vanessa Ribeiro Urbano ◽  
Milena Guedes Maniero ◽  
José Roberto Guimarães ◽  
Luis J. del Valle ◽  
Montserrat Pérez-Moya
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Pilot Plant ◽  
Environmental Water ◽  
Fenton Process ◽  
Experimental Conditions ◽  
Laboratory Bench ◽  
Degradation Rates ◽  
Bacterial Growth Inhibition ◽  
And Staphylococcus Aureus

Sulfaquinoxaline (SQX) has been detected in environmental water samples, where its side effects are still unknown. To the best of our knowledge, its oxidation by Fenton and photo-Fenton processes has not been previously reported. In this study, SQX oxidation, mineralization, and toxicity (Escherichia coli and Staphylococcus aureus bacteria) were evaluated at two different setups: laboratory bench (2 L) and pilot plant (15 L). The experimental design was used to assess the influence of the presence or absence of radiation source, as well as different H2O2 concentrations (94.1 to 261.9 mg L−1). The experimental conditions of both setups were: SQX = 25 mg L−1, Fe(II) = 10 mg L−1, pH 2.8 ± 0.1. Fenton and photo-Fenton were suitable for SQX oxidation and experiments resulted in higher SQX mineralization than reported in the literature. For both setups, the best process was the photo-Fenton (178.0 mg L−1 H2O2), for which over 90% of SQX was removed, over 50% mineralization, and bacterial growth inhibition less than 13%. In both set-ups, the presence or absence of radiation was equally important for sulfaquinoxaline oxidation; however, the degradation rates at the pilot plant were between two to four times higher than the obtained at the laboratory bench.

scholarly journals Catabolite Repression of Tryptophanase in Escherichia coli

1971 ◽  
Vol 105 (1) ◽  
pp. 303-312 ◽  
Author(s):  
James L. Botsford ◽  
R. D. DeMoss
Keyword(s):  
Escherichia Coli ◽  
Catabolite Repression
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