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.

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 Sequence and Analysis of a Plasmid-Encoded Mercury Resistance Operon from Mycobacterium marinum Identifies MerH, a New Mercuric Ion Transporter

2008 ◽  
Vol 191 (1) ◽  
pp. 439-444 ◽  
Author(s):  
Mathieu Schué ◽  
Lynn G. Dover ◽  
Gurdyal. S. Besra ◽  
Julian Parkhill ◽  
Nigel L. Brown
Keyword(s):  
Escherichia Coli ◽  
Dna Sequence ◽  
Mycobacterium Marinum ◽  
Mercury Resistance ◽  
Cysteine Residues ◽  
Ion Transporter ◽  
Mercuric Reductase ◽  
Mercuric Ion ◽  
Biological Analysis ◽  
Mercuric Ions

ABSTRACT In this study, we report the DNA sequence and biological analysis of a mycobacterial mercury resistance operon encoding a novel Hg2+ transporter. MerH was found to transport mercuric ions in Escherichia coli via a pair of essential cysteine residues but only when coexpressed with the mercuric reductase.

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