scholarly journals Involvement of a low-molecular-weight substance in in vitro activation of the molybdoenzyme respiratory nitrate reductase from a chlB mutant of Escherichia coli.

1987 ◽  
Vol 169 (10) ◽  
pp. 4678-4685 ◽  
Author(s):  
D H Boxer ◽  
D C Low ◽  
J Pommier ◽  
G Giordano
Keyword(s):  
Escherichia Coli ◽  
Molecular Weight ◽  
Nitrate Reductase ◽  
Low Molecular Weight ◽  
In Vitro Activation ◽  
Weight Substance ◽  
Respiratory Nitrate Reductase

scholarly journals Molybdoenzyme biosynthesis in Escherichia coli: in vitro activation of purified nitrate reductase from a chlB mutant.

1992 ◽  
Vol 174 (24) ◽  
pp. 7934-7940 ◽  
Author(s):  
C L Santini ◽  
C Iobbi-Nivol ◽  
C Romane ◽  
D H Boxer ◽  
G Giordano
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
In Vitro Activation

Bactericidal Effect of Sodium Chlorate on Escherichia coli O157:H7 and Salmonella Typhimurium DT104 in Rumen Contents In Vitro

2000 ◽  
Vol 63 (8) ◽  
pp. 1038-1042 ◽  
Author(s):  
ROBIN C. ANDERSON ◽  
SANDRA A. BUCKLEY ◽  
LEON F. KUBENA ◽  
LARRY H. STANKER ◽  
ROGER B. HARVEY ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Salmonella Typhimurium ◽  
Bactericidal Effect ◽  
Most Probable Number ◽  
Escherichia Coli O157 ◽  
Probable Number ◽  
E Coli ◽  
Respiratory Nitrate Reductase

Escherichia coli O157:H7 and Salmonella Typhimurium DT104 are important foodborne pathogens affecting the beef and dairy industries and strategies are sought to rid these organisms from cattle at slaughter. Both pathogens possess respiratory nitrate reductase that also reduces chlorate to the lethal chlorite ion. Because most anaerobes lack respiratory nitrate reductase, we hypothesized that chlorate may selectively kill E. coli O157:H7 and Salmonella Typhimurium DT104 but not potentially beneficial anaerobes. In support of this hypothesis, we found that concentrations of E. coli O157:H7 and Salmonella Typhimurium DT104 were reduced from approximately 1,000,000 colony forming units (CFU) to below our level of detection (≤10 CFU) following in vitro incubation (24 h) in buffered ruminal contents (pH 6.8) containing 5 mM added chlorate. In contrast, chlorate had little effect on the most probable number (mean ± SD) of total culturable anaerobes (ranging from 9.9 ± 0.72 to 10.7 ± 0.01 log10 cells/ml). Thus, chlorate was bactericidal to E. coli O157:H7 and Salmonella Typhimurium DT104 but not to potentially beneficial bacteria. The bactericidal effect of chlorate was concentration dependent (less at 1.25 mM) and markedly affected by pH (more bactericidal at pH 6.8 than pH 5.6).

scholarly journals Purification and Characterization of PBP4a, a New Low-Molecular-Weight Penicillin-Binding Protein fromBacillus subtilis

2001 ◽  
Vol 183 (5) ◽  
pp. 1595-1599 ◽  
Author(s):  
Colette Duez ◽  
Marc Vanhove ◽  
Xavier Gallet ◽  
Fabrice Bouillenne ◽  
Jean-Denis Docquier ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Weight ◽  
Binding Protein ◽  
Order Rate Constant ◽  
Low Molecular Weight ◽  
Penicillin Binding Protein ◽  
Purification And Characterization ◽  
The Third

ABSTRACT Penicillin-binding protein 4a (PBP4a) from Bacillus subtilis was overproduced and purified to homogeneity. It clearly exhibits dd-carboxypeptidase and thiolesterase activities in vitro. Although highly isologous to the Actinomadura sp. strain R39 DD-peptidase (B. Granier, C. Duez, S. Lepage, S. Englebert, J. Dusart, O. Dideberg, J. van Beeumen, J. M. Frère, and J. M. Ghuysen, Biochem. J. 282:781–788, 1992), which is rapidly inactivated by many β-lactams, PBP4a is only moderately sensitive to these compounds. The second-order rate constant (k 2/K) for the acylation of the essential serine by benzylpenicillin is 300,000 M−1s−1 for the Actinomadura sp. strain R39 peptidase, 1,400 M−1 s−1 for B. subtilis PBP4a, and 7,000 M−1 s−1 forEscherichia coli PBP4, the third member of this class of PBPs. Cephaloridine, however, efficiently inactivates PBP4a (k 2/K = 46,000 M−1 s−1). PBP4a is also much more thermostable than the R39 enzyme.

Permeability and Adsorption Capacity of Dialysis Membranes to Lipid A

1997 ◽  
Vol 20 (3) ◽  
pp. 144-152 ◽  
Author(s):  
C. Weber ◽  
I. Linsberger ◽  
M. Rafiee-Tehrani ◽  
D. Falkenhagen
Keyword(s):  
Escherichia Coli ◽  
Molecular Weight ◽  
Pseudomonas Aeruginosa ◽  
Lipid A ◽  
Low Molecular Weight ◽  
Dialysis Fluid ◽  
Adsorption Capacities ◽  
Model Substance ◽  
Dialysis Membranes

Hemodialysis membranes were tested in vitro for possible penetration by low molecular weight endotoxins containing lipid A. Using lipid A from Escherichia coli as a model substance for this kind of pyrogen, different dialyzers (F4, E3, Acepal 1300, Altraflux, F 40, Polyflux 110, Filtral 12, F 60) were challenged by tangential filtration in aqueous medium. All membranes exhibited impermability to lipid A (as well as to LPS from Pseudomonas aeruginosa), which was proved by additional experiments using culture filtrates of Pseudomonas aeruginosa in bicarbonate dialysis fluid, as well as by employing miniaturized dialyzers with synthetic lipid A as a contaminant. Furthermore, the highest adsorption capacities were found for polysulfone and polyamide membranes.

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