Inhibition of the induced synthesis of protocatechuate oxygenase by o-nitrobenzoic acid

1970 ◽  
Vol 16 (7) ◽  
pp. 609-614
Author(s):  
Karen F. Montgomery ◽  
Norman N. Durham
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Trichloroacetic Acid ◽  
Protocatechuic Acid ◽  
Viable Cell ◽  
Insoluble Fraction ◽  
Nitrobenzoic Acid ◽  
Cell Counts ◽  
Oxygenase Activity

The synthesis of protocatechuate oxygenase (EC. 1.13.1.3), an inducible enzyme, by Pseudomonas fluorescens was inhibited by o-nitrobenzoic acid. The inhibitor did not alter the oxygenase activity of induced cells. Viable cell counts indicated that o-nitrobenzoic acid, in the concentrations used in these experiments, did not kill the cells. The inhibitor decreased the incorporation of L-tryptophan-14C and DL-glutamic-14C acid into the hot trichloroacetic acid insoluble fraction of the cell, but had no effect on the uptake of either radioactive amino acids or the inducer, protocatechuic acid. The synthesis of β-galactosidase by Escherichia coli was also inhibited by o-nitrobenzoic acid. The results establish that one site of o-nitrobenzoic acid inhibition is associated with protein synthesis in the cell.

scholarly journals Association of nascent polypeptide with 30S ribosomal subunits

1973 ◽  
Vol 136 (4) ◽  
pp. 859-863 ◽  
Author(s):  
Michael Cannon ◽  
M. Amin A. Mirza ◽  
Margaret L. M. Anderson
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Trichloroacetic Acid ◽  
Sucrose Gradient ◽  
Gradient Centrifugation ◽  
Ribosomal Subunits ◽  
Nascent Polypeptide ◽  
Sucrose Gradient Centrifugation ◽  
Crude Extracts

1. Crude extracts of Escherichia coli were used to synthesize nascent peptides under the direction of endogenous mRNA and in the presence of radioactive amino acids. Analysis of such extracts by sucrose-gradient centrifugation in low Mg2+concentration has shown that after 2min of incubation approximately 14% of the total labelled protein recovered on the gradient, in association with whole ribosomes, sediments with 30S ribosomal subunits; this value rises to approximately 24% after 30min of incubation. The labelled protein associated with 30S ribosomal subunits is insoluble in hot trichloroacetic acid. 2. Similar results were also obtained in extracts that synthesized polypeptides under the direction of either of the synthetic polyribonucleotides poly(A) or poly(A,G,C,U). In contrast, however, analysis of crude extracts programmed in protein synthesis by poly(U) has indicated that under these conditions 30S ribosomal subunits have no associated polyphenylalanine; similarly there is little associated peptide after programming of extracts by poly(U,C).

scholarly journals The dynamic balance of import and export of zinc in Escherichia coli suggests a heterogeneous population response to stress

2015 ◽  
Vol 12 (106) ◽  
pp. 20150069 ◽  
Author(s):  
Hiroki Takahashi ◽  
Taku Oshima ◽  
Jon L. Hobman ◽  
Neil Doherty ◽  
Selina R. Clayton ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Zinc Concentration ◽  
Systems Approach ◽  
Model Simulation ◽  
Dynamic Balance ◽  
Model Fitting ◽  
Viable Cell ◽  
Population Heterogeneity ◽  
Cell Counts ◽  
Import And Export

Zinc is essential for life, but toxic in excess. Thus all cells must control their internal zinc concentration. We used a systems approach, alternating rounds of experiments and models, to further elucidate the zinc control systems in Escherichia coli . We measured the response to zinc of the main specific zinc import and export systems in the wild-type, and a series of deletion mutant strains. We interpreted these data with a detailed mathematical model and Bayesian model fitting routines. There are three key findings: first, that alternate, non-inducible importers and exporters are important. Second, that an internal zinc reservoir is essential for maintaining the internal zinc concentration. Third, our data fitting led us to propose that the cells mount a heterogeneous response to zinc: some respond effectively, while others die or stop growing. In a further round of experiments, we demonstrated lower viable cell counts in the mutant strain tested exposed to excess zinc, consistent with this hypothesis. A stochastic model simulation demonstrated considerable fluctuations in the cellular levels of the ZntA exporter protein, reinforcing this proposal. We hypothesize that maintaining population heterogeneity could be a bet-hedging response allowing a population of cells to survive in varied and fluctuating environments.

Performance of Some Heat-Sensitive Differential Agars Prepared and Melted by Microwave Energy1

1988 ◽  
Vol 51 (7) ◽  
pp. 577-578 ◽  
Author(s):  
C. LIANG ◽  
D. Y. C. FUNG
Keyword(s):  
Escherichia Coli ◽  
Cell Count ◽  
Viable Cell ◽  
Microwave Energy ◽  
Microwave Oven ◽  
Viable Cell Count ◽  
Streptococcus Faecalis ◽  
Cell Counts ◽  
Significant Difference ◽  
Conventional Boiling

The viable cell count performance of some heat-sensitive differential agars prepared and remelted by microwave energy was evaluated for Salmonella choleraesui, Streptococcus faecalis and Escherichia coli. The conventional boiling method was used for comparison. No significant difference was found between the microwave oven processed agar and the conventional-boiling processed agar in viable cell counts of the target bacteria. Heating and reheating of violet red bile agar, bismuth sulfite agar, and KF Streptococcus agar by both methods did not change agar performance. However, remelting of desoxycholate citrate agar by both methods resulted in a substantial lowering of viable cell counts.

The resistance of Escherichia coli to oxytetracycline

1969 ◽  
Vol 15 (9) ◽  
pp. 1077-1083 ◽  
Author(s):  
Jerold A. Last ◽  
Kazuo Izaki ◽  
J. F. Snell
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Irreversible Binding ◽  
Resistant Strains ◽  
Growth Of Bacteria

The effects of oxytetracycline on sensitive and resistant strains of Escherichia coli were studied in relation to: (1) growth of bacteria in shaken cultures, (2) incorporation of amino acids into polypeptides by cell-free extracts, (3) binding of aminoacyl-tRNA to ribosomes. Our results support the hypothesis that resistance to the antibiotic is due to impermeability of bacteria to the drug.Evidence is also presented that there is no irreversible binding of oxytetracycline at ribosomal sites involved in protein synthesis.

scholarly journals Intracellular Accumulation of Mannopine, an Opine Produced by Crown Gall Tumors, Transiently Inhibits Growth of Agrobacterium tumefaciens

2001 ◽  
Vol 14 (6) ◽  
pp. 793-803 ◽  
Author(s):  
Kun-Soo Kim ◽  
Chang-Ho Baek ◽  
Jeong Kug Lee ◽  
Jai Myung Yang ◽  
Stephen K. Farrand
Keyword(s):  
Amino Acids ◽  
Agrobacterium Tumefaciens ◽  
Sole Carbon Source ◽  
Viable Cell ◽  
Insertion Mutation ◽  
Intracellular Accumulation ◽  
Cell Counts ◽  
Hexose Sugars ◽  
Crown Gall Tumors ◽  
Resistant Mutants

pYDH208, a cosmid clone from the octopine-mannityl opine-type tumor-inducing (Ti) plasmid pTi15955 confers utilization of mannopine (MOP) and agropine (AGR) on Agrobacterium tumefaciens strain NT1. NT1 harboring pYDH208 with an insertion mutation in mocC, which codes for MOP oxidoreductase, not only fails to utilize MOP as a sole carbon source, but also was inhibited in its growth by MOP and AGR. In contrast, the growth of mutants with insertions in other tested moc genes was not inhibited by either opine. Growth of strains NT1 or UIA5, a derivative of C58 that lacks pAtC58, was not inhibited by MOP, but growth of NT1 or UIA5 harboring pRE10, which codes for the MOP transport system, was inhibited by the opine. When a clone expressing mocC was introduced, the growth of strain NT1(pRE10) was not inhibited by MOP, although UIA5(pRE10) was still weakly inhibited. In strain NT1(pRE10, mocC), santhopine (SOP), produced by the oxidation of MOP by MocC, was further degraded by functions encoded by pAtC58. These results suggest that MOP and, to a lesser extent, SOP are inhibitory when accumulated intracellularly. The growth of NT1(pRE10), as measured by turbidity and viable cell counts, ceased upon the addition of MOP but restarted in a few hours. Regrowth was partly the result of the outgrowth of spontaneous MOP-resistant mutants and partly the adaptation of cells to MOP in the medium. Chrysopine, isochrysopine, and analogs of MOP in which the glutamine residue is substituted with other amino acids were barely taken up by NT1(pRE10) and were not inhibitory to growth of the strain. Sugar analogs of MOP were inhibitory, and those containing sugars in the D form were more inhibitory than those containing sugars in the L form. MOP analogs containing hexose sugars were more inhibitory than those containing sugars with three, four, or five carbon atoms. Mutants of NT1(pRE10) that are resistant to MOP arose in the zone of growth inhibition. Genetic and physiological analyses indicate that the mutations are located on pRE10 and abolish uptake of the opine.

Hymenolepis diminuta: The Microbial Fauna, Nutritional Gradients, and Physicochemical Characteristics of the Small Intestine of Uninfected and Parasitized Rats

1971 ◽  
Vol 49 (11) ◽  
pp. 972-984 ◽  
Author(s):  
D. F. Mettrick
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Small Intestine ◽  
Trichloroacetic Acid ◽  
Inverse Correlation ◽  
Physicochemical Characteristics ◽  
Hymenolepis Diminuta ◽  
Soluble Carbohydrate ◽  
Molar Ratios ◽  
Number Of Microorganisms

In uninfected rats the amount of trichloroacetic acid (TCA) soluble and insoluble carbohydrate in the small intestine declined steadily from duodenum to ileum. In rats infected with 10 16-day-old Hymenolepis diminuta these gradients were reversed and there was a 54% increase in the amount of TCA-soluble carbohydrate, and a 110% increase in the amount of glucose present in the luminal contents.In uninfected rats the amounts of TCA-soluble and -insoluble nitrogen and of total lipid in the small intestine were considerably more than in the intestine of infected rats. The differences may represent utilization by the worms of these nutrients.In parasitized rats the concentrations and molar ratios of the amino acids of the intestinal amino acid pool were significantly different (P < 0.001) in every region of the gut from those in uninfected animals.The intestinal pH of parasitized rats was lower than that in uninfected rats, and the pH gradient showed an inverse correlation with worm biomass and lactic acid distribution.The number of microorganisms present in the small intestine and colon of parasitized rats was less than half that in uninfected animals. Escherichia coli and the coliforms showed the greatest decrease in numbers. Other common aerobes were also markedly reduced in number. Anaerobic enterococci and yeasts were absent in the parasitized animals; anaerobic streptococci and micrococci were restricted to the ileum.

Isolation and Purification of Colicin ECL 12, a Bacteriocin That Inhibits Strains of Escherichia coli O157:H7†

1997 ◽  
Vol 60 (12) ◽  
pp. 1520-1528 ◽  
Author(s):  
WANDA J. LYON ◽  
DENNIS G. OLSON
Keyword(s):  
Escherichia Coli ◽  
Proteolytic Enzymes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Viable Cell ◽  
Exchange Chromatography ◽  
Isolation And Purification ◽  
E Coli ◽  
Log Reduction ◽  
Cell Counts

A swine fecal isolate, identified as Escherichia coli ECL12, was found to produce an antimicrobial substance designated as colicin ECL12. Colicin ECL12 was inhibitory against 20 strains of E. coli O157:H7 previously isolated from both human and bovine feces. Identification of the producer strain was determined phenotypically by biochemical and morphological tests. Colicin ECL12 was sensitive to several proteolytic enzymes. Adsorption of colicin ECL12 to sensitive cells of E. coli O157:H7 was bactericidal, resulting in a 2 log reduction in viable cell counts. Colicin ECL12 was purified from strain ECL12 by cell extraction and ion-exchange chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of colicin ECL12 resolved a single protein with a molecular weight of approximately 65,000.

scholarly journals Bactericidal Activity of ACH-702 against Nondividing and Biofilm Staphylococci

2012 ◽  
Vol 56 (7) ◽  
pp. 3812-3818 ◽  
Author(s):  
Steven D. Podos ◽  
Jane A. Thanassi ◽  
Melissa Leggio ◽  
Michael J. Pucci
Keyword(s):  
Protein Synthesis ◽  
Stationary Phase ◽  
Bactericidal Activity ◽  
Bacterial Infections ◽  
De Novo ◽  
Viable Cell ◽  
Bacterial Cells ◽  
Protein Synthesis Inhibitors ◽  
Content Type ◽  
Cell Counts

ABSTRACTMany bacterial infections involve slow or nondividing bacterial growth states and localized high cell densities. Antibiotics with demonstrated bactericidal activity rarely remain bactericidal at therapeutic concentrations under these conditions. The isothiazoloquinolone (ITQ) ACH-702 is a potent, bactericidal compound with activity against many antibiotic-resistant pathogens, including methicillin-resistantStaphylococcus aureus(MRSA). We evaluated its bactericidal activity under conditions where bacterial cells were not dividing and/or had slowed their growth. AgainstS. aureuscultures in stationary phase, ACH-702 showed concentration-dependent bactericidal activity and achieved a 3-log-unit reduction in viable cell counts within 6 h of treatment at ≥16× MIC values; in comparison, the bactericidal quinolone moxifloxacin and the additional comparator compounds vancomycin, linezolid, and rifampin at 16× to 32× MICs showed little or no bactericidal activity against stationary-phase cells. ACH-702 at 32× MIC retained bactericidal activity against stationary-phaseS. aureusacross a range of inoculum densities. ACH-702 did not kill cold-arrested cells yet remained bactericidal against cells arrested by protein synthesis inhibitors, suggesting that its bactericidal activity against nondividing cells requires active metabolism but notde novoprotein synthesis. ACH-702 also showed a degree of bactericidal activity at 16× MIC againstS. epidermidisbiofilm cells that was superior to that of moxifloxacin, rifampin, and vancomycin. The bactericidal activity of ACH-702 against stationary-phase staphylococci and biofilms suggests potential clinical utility in infections containing cells in these physiological states.

scholarly journals Validation of a Noninvasive, Real-Time Imaging Technology Using Bioluminescent Escherichia coli in the Neutropenic Mouse Thigh Model of Infection

2001 ◽  
Vol 45 (1) ◽  
pp. 129-137 ◽  
Author(s):  
H. L. Rocchetta ◽  
C. J. Boylan ◽  
J. W. Foley ◽  
P. W. Iversen ◽  
D. L. LeTourneau ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Real Time ◽  
Antimicrobial Agents ◽  
Viable Cell ◽  
Multicopy Plasmid ◽  
In Vivo Evaluation ◽  
Therapeutic Success ◽  
Cell Counts

ABSTRACT A noninvasive, real-time detection technology was validated for qualitative and quantitative antimicrobial treatment applications. Thelux gene cluster of Photorhabdus luminescenswas introduced into an Escherichia coli clinical isolate, EC14, on a multicopy plasmid. This bioluminescent reporter bacterium was used to study antimicrobial effects in vitro and in vivo, using the neutropenic-mouse thigh model of infection. Bioluminescence was monitored and measured in vitro and in vivo with an intensified charge-coupled device (ICCD) camera system, and these results were compared to viable-cell determinations made using conventional plate counting methods. Statistical analysis demonstrated that in the presence or absence of antimicrobial agents (ceftazidime, tetracycline, or ciprofloxacin), a strong correlation existed between bioluminescence levels and viable cell counts in vitro and in vivo. Evaluation of antimicrobial agents in vivo could be reliably performed with either method, as each was a sound indicator of therapeutic success. Dose-dependent responses could also be detected in the neutropenic-mouse thigh model by using either bioluminescence or viable-cell counts as a marker. In addition, the ICCD technology was examined for the benefits of repeatedly monitoring the same animal during treatment studies. The ability to repeatedly measure the same animals reduced variability within the treatment experiments and allowed equal or greater confidence in determining treatment efficacy. This technology could reduce the number of animals used during such studies and has applications for the evaluation of test compounds during drug discovery.

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