scholarly journals INHIBITION OF ESCHERICHIA COLI BY p-AMINOBENZOIC ACID AND ITS REVERSAL BY p-HYDROXYBENZOIC ACID

1951 ◽  
Vol 94 (3) ◽  
pp. 243-254 ◽  
Author(s):  
Bernard D. Davis
Keyword(s):  
Shikimic Acid ◽  
Growth Inhibitor ◽  
Metabolic Effects ◽  
Hydroxybenzoic Acid ◽  
Aminobenzoic Acid ◽  
Chlorobenzoic Acid ◽  
E Coli ◽  
Nitrobenzoic Acid ◽  
Low Concentrations ◽  
High Concentrations

p-Aminobenzoic acid (PABA) exerts three metabolic effects on E. coli: it acts as a normal vitamin at low concentrations, as a source of another vitamin, p-hydroxybenzoic acid (POB), at moderate concentrations, and as a growth inhibitor at high concentrations (150 to 1600 µg./ml.). The inhibition is competitively reversed by POB in 1/100 the concentration of PABA. The inhibition is also reversed to a limited extent by shikimic acid and compound X, precursors of POB. p-Nitrobenzoic acid is an inhibitory competitor of both POB and PABA. The retardation of growth produced by PABA and other competitive analogues of POB (p-nitrobenzoic acid; 4,4'-dihydroxydiphenyl sulfone; phenosulfazole) is converted to complete bacteriostasis by the addition of L-aspartic acid in a remarkably low concentration (1 µg./ml.)) without change in the competitive ratio with POB. The mechanism underlying this synergism is not clear. In contrast to wild type, mutants that require POB not only are inhibited by much lower concentrations of the above analogues, but also show inhibition by weaker competitors of POB such as p-hydroxybenzenesulfonamide, p-chlorobenzoic acid, and p-fluorobenzoic acid.

Mechanisms of vanadium action: insulin-mimetic or insulin-enhancing agent?

2000 ◽  
Vol 78 (10) ◽  
pp. 829-847 ◽  
Author(s):  
Margaret C Cam ◽  
Roger W Brownsey ◽  
John H McNeill
Keyword(s):  
Lipid Metabolism ◽  
Metabolic Effects ◽  
Isolated Cells ◽  
Insulin Mimetic ◽  
Endogenous Insulin ◽  
Carbohydrate And Lipid Metabolism ◽  
Low Concentrations ◽  
Tissue Sensitivity ◽  
High Concentrations

The demonstration that the trace element vanadium has insulin-like properties in isolated cells and tissues and in vivo has generated considerable enthusiasm for its potential therapeutic value in human diabetes. However, the mechanisms by which vanadium induces its metabolic effects in vivo remain poorly understood, and whether vanadium directly mimics or rather enhances insulin effects is considered in this review. It is clear that vanadium treatment results in the correction of several diabetes-related abnormalities in carbohydrate and lipid metabolism, and in gene expression. However, many of these in vivo insulin-like effects can be ascribed to the reversal of defects that are secondary to hyperglycemia. The observations that the glucose-lowering effect of vanadium depends on the presence of endogenous insulin whereas metabolic homeostasis in control animals appears not to be affected, suggest that vanadium does not act completely independently in vivo, but augments tissue sensitivity to low levels of plasma insulin. Another crucial consideration is one of dose-dependency in that insulin-like effects of vanadium in isolated cells are often demonstrated at high concentrations that are not normally achieved by chronic treatment in vivo and may induce toxic side effects. In addition, vanadium appears to be selective for specific actions of insulin in some tissues while failing to influence others. As the intracellular active forms of vanadium are not precisely defined, the site(s) of action of vanadium in metabolic and signal transduction pathways is still unknown. In this review, we therefore examine the evidence for and against the concept that vanadium is truly an insulin-mimetic agent at low concentrations in vivo. In considering the effects of vanadium on carbohydrate and lipid metabolism, we conclude that vanadium acts not globally, but selectively and by enhancing, rather than by mimicking the effects of insulin in vivo.Key words: vanadium, insulin-mimetic, insulin-like, insulin-enhancing.

scholarly journals Glutathione-Dependent Conversion ofN-Ethylmaleimide to the Maleamic Acid by Escherichia coli: an Intracellular Detoxification Process

2000 ◽  
Vol 66 (4) ◽  
pp. 1393-1399 ◽  
Author(s):  
D. McLaggan ◽  
H. Rufino ◽  
M. Jaspars ◽  
I. R. Booth
Keyword(s):  
Escherichia Coli ◽  
Time Course ◽  
E Coli ◽  
Transient Activation ◽  
Low Concentrations ◽  
Maleamic Acid ◽  
High Concentrations ◽  
Hydrolysis Of ◽  
Strong Activator ◽  
Detoxification Process

ABSTRACT The electrophile N-ethylmaleimide (NEM) elicits rapid K+ efflux from Escherichia coli cells consequent upon reaction with cytoplasmic glutathione to form an adduct, N-ethylsuccinimido-S-glutathione (ESG) that is a strong activator of the KefB and KefC glutathione-gated K+ efflux systems. The fate of the ESG has not previously been investigated. In this report we demonstrate that NEM andN-phenylmaleimide (NPM) are rapidly detoxified by E. coli. The detoxification occurs through the formation of the glutathione adduct of NEM or NPM, followed by the hydrolysis of the imide bond after which N-substituted maleamic acids are released. N-Ethylmaleamic acid is not toxic to E. coli cells even at high concentrations. The glutathione adducts are not released from cells, and this allows glutathione to be recycled in the cytoplasm. The detoxification is independent of new protein synthesis and NAD+-dependent dehydrogenase activity and entirely dependent upon glutathione. The time course of the detoxification of low concentrations of NEM parallels the transient activation of the KefB and KefC glutathione-gated K+ efflux systems.

Cellular nicotinamide adenine dinucleotide (NADH) as an indicator of bacterial metabolic activity dynamics in activated sludge

2009 ◽  
Vol 60 (3) ◽  
pp. 783-791 ◽  
Author(s):  
M. L. Wos ◽  
P. C. Pollard
Keyword(s):  
Activated Sludge ◽  
Metabolic Activity ◽  
Nicotinamide Adenine Dinucleotide ◽  
Nicotinamide Adenine ◽  
Overflow Metabolism ◽  
Extracellular Medium ◽  
Terminal Electron Acceptor ◽  
E Coli ◽  
Low Concentrations ◽  
High Concentrations

In this study, native fluorescent nicotinamide adenine dinucleotide (NADH) was used as a direct indicator of bacterial metabolic activity in activated sludge. Specific NADH concentration was dynamic and varied between 106–108 molecules per bacterial cell. Low concentrations (106–107 NADH molecules cell−1) indicate efficient bacterial metabolic activity while high concentrations (107–108 NADH molecules cell−1) indicate inefficient bacterial metabolic activity. Specific [NADH] did not correlate to changes in dissolved organic carbon, but increases correlated to decreases in oxygen uptake rates. Perhaps a lack of oxygen as the terminal electron acceptor prevented efficient reoxidization of NADH to NAD+, which resulted in an accumulation of NADH within the cells. Also, significant amounts of NADH were released and accumulated into the extracellular medium of metabolically active E. coli cells in log phase. Such overflow metabolism may be the product of favourable conditions. Thus, the flux of both specific intracellular and extracellular [NADH] indicates the dynamics of bacterial metabolic activity in activated sludge.

Biofilm Growth of Escherichia coli Is Subject to cAMP-Dependent and cAMP-Independent Inhibition

2015 ◽  
Vol 25 (2-3) ◽  
pp. 209-225 ◽  
Author(s):  
Sarah L. Sutrina ◽  
Kia Daniel ◽  
Michael Lewis ◽  
Naomi T. Charles ◽  
Cherysa K.E. Anselm ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Catabolite Repression ◽  
Ph Effects ◽  
Wild Type ◽  
Inhibitory Effects ◽  
Phosphotransferase System ◽  
Biofilm Growth ◽  
E Coli ◽  
Low Concentrations ◽  
High Concentrations

We established that <i>Escherichia coli </i>strain 15 (ATCC 9723) produces both curli and cellulose, and forms robust biofilms. Since this strain is wild type with respect to the phosphoenolpyruvate:sugar phosphotransferase system (PTS), it is an ideal strain in which to investigate the effects of the PTS on the biofilm growth of <i>E. coli</i>. We began by looking into the effects of PTS and non-PTS sugars on the biofilm growth of this strain. All the sugars tested tended to activate biofilm growth at low concentrations but to inhibit biofilm growth at high concentrations. Acidification of the medium was an inhibitory factor in the absence of buffer, but buffering to prevent a pH drop did not prevent the inhibitory effects of the sugars. The concentration at which inhibition set in varied from sugar to sugar. For most sugars, cyclic (c)AMP counteracted the inhibition at the lowest inhibitory concentrations but became ineffective at higher concentrations. Our results suggest that cAMP-dependent catabolite repression, which is mediated by the PTS in <i>E. coli</i>, plays a role in the regulation of biofilm growth in response to sugars. cAMP-independent processes, possibly including Cra, also appear to be involved, in addition to pH effects.

scholarly journals Surface Plasmon Resonance Assay for Real-Time Monitoring of Somatic Coliphages in Wastewaters

2008 ◽  
Vol 74 (13) ◽  
pp. 4054-4058 ◽  
Author(s):  
Cristina García-Aljaro ◽  
Xavier Muñoz-Berbel ◽  
A. Toby A. Jenkins ◽  
Anicet R. Blanch ◽  
Francesc Xavier Muñoz
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Limit Of Detection ◽  
Mass Density ◽  
Binding Constants ◽  
Somatic Coliphages ◽  
E Coli ◽  
Low Concentrations ◽  
High Concentrations

ABSTRACT The surface plasmon resonance (SPR) technique is a well-established method for the measurement of molecules binding to surfaces and the quantification of binding constants between surface-immobilized proteins and proteins in solution. In this paper we describe an extension of the methodology to study bacteriophage-bacterium interactions. A two-channel microfluidic SPR sensor device was used to detect the presence of somatic coliphages, a group of bacteriophages that have been proposed as fecal pollution indicators in water, using their host, Escherichia coli WG5, as a target for their selective detection. The bacterium, E. coli WG5, was immobilized on gold sensor chips using avidin-biotin and bacteriophages extracted from wastewater added. The initial binding of the bacteriophage was observed at high concentrations, and a separate, time-delayed cell lysis event also was observed, which was sensitive to bacteriophage at low concentrations. As few as 1 PFU/ml of bacteriophage injected into the chamber could be detected after a phage incubation period of 120 min, which equates to an approximate limit of detection of around 102 PFU/ml. The bacteriophage-bacterium interaction appeared to cause a structural change in the surface-bound bacteria, possibly due to collapse of the cell, which was observed as an increase in mass density on the sensor chip. These results suggest that this methodology could be employed for future biosensor technologies and for quantification of the bacteriophage concentration.

scholarly journals Cloning and Expression of the Inositol Monophosphatase Gene from Methanococcus jannaschii and Characterization of the Enzyme

1998 ◽  
Vol 64 (7) ◽  
pp. 2609-2615 ◽  
Author(s):  
Liangjing Chen ◽  
Mary F. Roberts
Keyword(s):  
Gene Product ◽  
Heat Stability ◽  
Cloning And Expression ◽  
Hyperthermophilic Archaea ◽  
Methanococcus Jannaschii ◽  
Inositol Monophosphatase ◽  
E Coli ◽  
Low Concentrations ◽  
High Concentrations

ABSTRACT Inositol monophosphatase (EC 3.1.3.25 ) plays a pivotal role in the biosynthesis of di-myo-inositol-1,1′-phosphate, an osmolyte found in hyperthermophilic archaea. Given the sequence homology between the MJ109 gene product of Methanococcus jannaschii and human inositol monophosphatase, the MJ109 gene was cloned and expressed in Escherichia coli and examined for inositol monophosphatase activity. The purified MJ109 gene product showed inositol monophosphatase activity with kinetic parameters (Km = 0.091 ± 0.016 mM;V max = 9.3 ± 0.45 μmol of Pi min−1 mg of protein−1) comparable to those of mammalian and E. coli enzymes. Its substrate specificity, Mg2+ requirement, Li+inhibition, subunit association (dimerization), and heat stability were studied and compared to those of other inositol monophosphatases. The lack of inhibition by low concentrations of Li+ and high concentrations of Mg2+ and the high rates of hydrolysis of glucose-1-phosphate and p-nitrophenylphosphate are the most pronounced differences between the archaeal inositol monophosphatase and those from other sources. The possible causes of these kinetic differences are discussed, based on the active site sequence alignment between M. jannaschii and human inositol monophosphatase and the crystal structure of the mammalian enzyme.

Reperfusion-induced arrhythmias: mechanisms of protection by glucose and mannitol

1988 ◽  
Vol 254 (5) ◽  
pp. H862-H870 ◽  
Author(s):  
M. Bernier ◽  
D. J. Hearse
Keyword(s):  
Radical Scavenging ◽  
Experimental Period ◽  
Free Radical Scavenging ◽  
Metabolic Effects ◽  
Low Concentrations ◽  
Rat Hearts ◽  
High Concentrations ◽  
Radical Scavenging Properties ◽  
Isolated Rat ◽  
Antiarrhythmic Effects

Isolated rat hearts (n = 15/group) were subjected to regional ischemia (10 min) and reperfusion (3 min). Mannitol (5, 11, 25, 50, 55, 61, or 75 mM included in the perfusate throughout) reduced reperfusion-induced sustained ventricular fibrillation (VF) from its control incidence of 93% (14/15) to 80, 80, 40, 27, 47, 80, and 80%, respectively. Addition of glucose (11 mM) potentiated this effect, VF now fell to 87, 47, 33, 7, 7, 7, 13, and 13%, respectively. However, 11 mM glucose alone exerted no antiarrhythmic effects. When hearts (n = 15/group) were perfused with identical osmotic loads of mannitol plus glucose (11 + 50, 50 + 11, 61 + 0, or 0 + 61 mM, respectively), very different antiarrhythmic effects were observed. When given throughout the experimental period, glucose alone (0, 11, 25, 50 or 61 mM) had no effect on the incidence of VF (93, 87, 47, 53, and 20%, respectively), but when glucose was added 2 min before reperfusion, improved protection was observed (VF: 93, 87, 40, 27, and 13%, respectively). Our results suggest that the osmotic and free-radical scavenging properties of hexoses are relatively unimportant in relation to their antiarrhythmic effects. The metabolic effects are complex, suggesting that low concentrations of glucose may be beneficial, whereas high concentrations may be detrimental.

scholarly journals Synthetic, Spectroscopic and Biological Studies on Some μ-Oxy-bis[triphenylantimony(V)]carboxylates and Cyclic Organoantimonates

2021 ◽  
Vol 33 (2) ◽  
pp. 387-392
Author(s):  
Surjeet S ingh ◽  
Neha Bahuguna ◽  
Kiran Singhal ◽  
Prem Raj
Keyword(s):  
Molecular Weight ◽  
Molar Ratio ◽  
Aminobenzoic Acid ◽  
Conductivity Data ◽  
Melting Points ◽  
Chlorobenzoic Acid ◽  
Nitrobenzoic Acid ◽  
Silver Salts ◽  
Biological Studies ◽  
Ft Ir

A series of hitherto unreported μ-oxy-bis[triphenylantimony(V)]dicarboxylates and μ-oxy-bis[triphenylantimony(V)] chlorocarboxylates of general formula Ph3Sb(L)-O-Sb(L)Ph3 and Ph3Sb(Cl)-O-Sb(L)Ph3, respectively have been synthesized by the metathetical reaction of μ-oxybis-[triphenylantimony(V)]dichloride and silver salts of corresponding carboxylic acids in 1:2 and 1:1 molar ratio [where L = thiosalicyclic acid, p-nitrobenzoic acid, p-aminobenzoic acid, p-fluorobenzoic acid, o-chlorobenzoic acid]. The newly isolated antimony carboxylates have been identified on the basis of melting points, elemental analysis, FT-IR, 1H NMR,13C NMR, 19F NMR. The molecular weight and conductivity data indicate the monomeric and non-electrolytic behaviour in solution. Compounds have been evaluated for their antifungal and antibacterial activity.

scholarly journals Influence of Zinc Sulphate on the Probiotic Properties of Lactobacillus plantarum CCM 7102

2019 ◽  
Vol 63 (2) ◽  
pp. 45-54 ◽  
Author(s):  
D. Mudroňová ◽  
S. Gancarčíková ◽  
R. Nemcová
Keyword(s):  
Growth Rate ◽  
Zinc Sulphate ◽  
Low Ph ◽  
Growth Media ◽  
Probiotic Properties ◽  
E Coli ◽  
Low Concentrations ◽  
High Concentrations ◽  
Strain Dependent

Abstract The effects of zinc sulphate on selected properties of L. plantarum CCM 7102 were tested in vitro. The resistance of lactobacilli to higher concentrations of ZnSO4 (up to 5000 mg Zn2+.l−1) in growth media was strain-dependent. Further studies were carried out on the most resistant strain of L. plantarum CCM 7102. While the addition of low concentrations of zinc sulphate into the growth media (< 100 mg Zn2+.l−1) did not influence the properties of L. plantarum CCM 7102, the concentrations of 100—500 mg Zn2+.l−1 stimulated: the growth rate, production of lactic acid, adhesion to porcine enterocytes and the inhibition of pathogens E. coli O8:K88+ent+, S. enterica and S. Typhimurium. Conversely, however, high concentrations > 500 mg Zn2+.l−1 inhibited these properties. The addition of zinc (250 mg Zn2+.l−1) did not affect the resistance to antimicrobials, low pH, and the resistance to bile salt was affected only weakly. Zinc-resistant probiotic Lactobacillus strains are suitable for use in feedstuffs with a higher content of zinc designed for the prevention of post weaning diarrhoea in pigs.

Immunogold labeling of CMP-KDO synthetase produced by recombinant E. Coli cells

1987 ◽  
Vol 45 ◽  
pp. 924-925
Author(s):  
F. A. Durum ◽  
R. G. Goldman ◽  
T. J. Bolling ◽  
M. F. Miller
Keyword(s):  
Inclusion Bodies ◽  
Large Scale ◽  
Recombinant Dna ◽  
Test System ◽  
Cell Protein ◽  
Gram Negative Bacteria ◽  
Cytoplasmic Inclusions ◽  
Isolation And Purification ◽  
E Coli ◽  
Low Concentrations

CMP-KDO synthetase (CKS) is an enzyme which plays a key role in the synthesis of LPS, an outer membrane component unique to gram negative bacteria. CKS activates KDO to CMP-KDO for incorporation into LPS. The enzyme is normally present in low concentrations (0.02% of total cell protein) which makes it difficult to perform large scale isolation and purification. Recently, the gene for CKS from E. coli was cloned and various recombinant DNA constructs overproducing CKS several thousandfold (unpublished data) were derived. Interestingly, no cytoplasmic inclusions of overproduced CKS were observed by EM (Fig. 1) which is in contrast to other reports of large proteinaceous inclusion bodies in various overproducing recombinant strains. The present immunocytochemical study was undertaken to localize CKS in these cells.Immune labeling conditions were first optimized using a previously described cell-free test system. Briefly, this involves soaking small blocks of polymerized bovine serum albumin in purified CKS antigen and subjecting them to various fixation, embedding and immunochemical conditions.

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