THE EFFECT OF pH ON SURFACE STRUCTURE AND MORPHOLOGY OF THE EXTREME HALOPHILE, HALOBACTERIUM CUTIRUBRUM

1963 ◽  
Vol 9 (1) ◽  
pp. 53-63 ◽  
Author(s):  
D. J. Kushner ◽  
S. T. Bayley
Keyword(s):  
Surface Structure ◽  
Morphological Changes ◽  
Low Ph ◽  
Extreme Halophile ◽  
Intact Cells ◽  
Structure And Morphology ◽  
Ph Values ◽  
Pattern Characteristic ◽  
Low Ionic Strength ◽  
Sphere Formation

At low pH values much of the surface structure of Halobacterium cutirubrum is maintained, even in the absence of the high salt concentration normally needed to keep this organism from dissolving. If the pH is then raised in solutions of low ionic strength, the cells dissolve. Sphere formation takes place below pH 3 in the absence of salt, and at pH values of about 4 and about 11 in the presence of 4.5 M NaCl. In the latter, there is at first little leakage of intracellular constituents, and the surface of the spheres retains the woven pattern characteristic of the surface of the untreated cell. Below pH 3, this pattern disappears, and the cells become almost completely or completely permeable. In 1% acetic acid, NaCl and KCl have the same effect on cell morphology, in contrast to their differential effects on intact cells. The morphological changes observed appear primarily due to changes in the cell membrane, and are not caused by osmotic pressure.

scholarly journals The purification and properties of a single chicken pepsinogen fraction and the pepsin derived from it

1973 ◽  
Vol 133 (1) ◽  
pp. 105-115 ◽  
Author(s):  
Margaret L. Green ◽  
Joanna M. Llewellin
Keyword(s):  
Amino Acids ◽  
Thiol Group ◽  
Enzymic Activity ◽  
Low Ph ◽  
Carboxypeptidase A ◽  
Molecular Weights ◽  
Ph Values ◽  
Purification And Properties ◽  
Terminal Amino ◽  
Low Ionic Strength

1. Evidence is given for the presence of at least five pepsinogens in a crude extract of mixed chicken stomachs. One of these was purified and could be activated to yield a single pepsin. 2. The molecular weights of the pepsinogen and pepsin were 36000 and 34000 respectively. The pepsin associated at low pH values and low ionic strength. 3. The amino acid analyses of both proteins are given. The pepsin was devoid of phosphate but contained carbohydrate. 4. The N-terminal amino acids of pepsinogen and pepsin were serine and threonine respectively. Five amino acids were released by carboxypeptidase A and it was deduced that serine may be the C-terminal one. 5. Each protein contained one thiol group per molecule as determined by titration with p-chloromercuribenzoate. The rate of the reaction was very rapid with pepsin, but much slower with pepsinogen, although the same group appeared to react in both instances. The enzymic activity of pepsin was unaffected by the modification. 6. The isoionic point of the pepsin was close to pH4.0 and the enzyme was stable for long periods at pH values up to 7.0. 7. The enzyme hydrolysed bisphenyl sulphite almost as rapidly as did pig pepsin A.

scholarly journals Adaptation of Lactobacillus plantarum IMDO 130201, a Wheat Sourdough Isolate, to Growth in Wheat Sourdough Simulation Medium at Different pH Values through Differential Gene Expression

2011 ◽  
Vol 77 (10) ◽  
pp. 3406-3412 ◽  
Author(s):  
Gino Vrancken ◽  
Luc De Vuyst ◽  
Tom Rimaux ◽  
Joke Allemeersch ◽  
Stefan Weckx
Keyword(s):  
Gene Expression ◽  
Lactobacillus Plantarum ◽  
Differential Gene Expression ◽  
Lipoteichoic Acid ◽  
Low Ph ◽  
Exponential Growth Phase ◽  
Cellular Mechanisms ◽  
Content Type ◽  
Ph Values ◽  
Differential Gene

ABSTRACTSourdough is a very competitive and challenging environment for microorganisms. Usually, a stable microbiota composed of lactic acid bacteria (LAB) and yeasts dominates this ecosystem. Although sourdough is rich in carbohydrates, thus providing an ideal environment for microorganisms to grow, its low pH presents a particular challenge. The nature of the adaptation to this low pH was investigated forLactobacillus plantarumIMDO 130201, an isolate from a laboratory wheat sourdough fermentation. Batch fermentations were carried out in wheat sourdough simulation medium, and total RNA was isolated from mid-exponential-growth-phase cultures, followed by differential gene expression analysis using a LAB functional gene microarray. At low pH values, an increased expression of genes involved in peptide and amino acid metabolism was found as well as that of genes involved in plantaricin production and lipoteichoic acid biosynthesis. The results highlight cellular mechanisms that allowL. plantarumto function at a low environmental pH.

scholarly journals Mechanism of Coagulation of Humic Acid in Presence of Metal Ion Coagulants at Low pH Values

1970 ◽  
Vol 73 (5) ◽  
pp. 874-878 ◽  
Author(s):  
Takao YOTSUYANAGI ◽  
Katsumi GOTO ◽  
Masaichi NAGAYAMA
Keyword(s):  
Humic Acid ◽  
Metal Ion ◽  
Low Ph ◽  
Ph Values

EFFECT OF ALKYL BENZENE SULPHONATE ON YEAST METABOLISM

1963 ◽  
Vol 9 (1) ◽  
pp. 117-127
Author(s):  
E. R. Blakley
Keyword(s):  
Cell Wall ◽  
Candida Utilis ◽  
Complete Inhibition ◽  
Enzymatic Reactions ◽  
Alkyl Benzene ◽  
Intact Cells ◽  
Yeast Metabolism ◽  
Ph Values ◽  
Upper Limit ◽  
Yeast Protoplasts

The rate of fermentation of glucose by suspensions of Candida utilis at acid pH values is reduced by alkyl benzene sulphonate in the range 75 to 250 γ/ml. Concentrations of alkyl benzene sulphonate below 75 γ/ml decrease the rate of fermentation of glucose above pH 7 and respiration at all pH values. An upper limit of 70 to 90% inhibition of fermentation or respiration is obtained at concentrations of alkyl benzene sulphonate above 250 γ/ml, except at pH 4.2 where complete inhibition is obtained. The effect of alkyl benzene sulphonate on the fermentation of glucose by yeast protoplasts is similar to the effect observed for intact yeasts. Some enzymatic reactions of cell-free extracts are inhibited by concentrations of alkyl benzene sulphonate lower than that required to affect fermentation by intact cells. The enzyme components of the cell-free preparation appear to vary in their sensitivity to the surfactant. The results support the view that the surfactant in the micellar form disrupts the cell wall of the yeast, and unassociated molecules inactivate some enzymes vital for the metabolism of the cell.

Interaction of Gram-Negative Bacteria with the Lysosomal Fraction of Polymorphonuclear Leukocytes II. Changes in the Cell Envelope of Escherichia coli

1970 ◽  
Vol 1 (3) ◽  
pp. 311-318
Author(s):  
D. Friedberg ◽  
I. Friedberg ◽  
M. Shilo
Keyword(s):  
Escherichia Coli ◽  
Polymorphonuclear Leukocytes ◽  
Cytoplasmic Membrane ◽  
Morphological Changes ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Intact Cells ◽  
Lysosomal Fraction ◽  
E Coli ◽  
Absorbing Material

Interaction of lysosomal fraction with Escherichia coli caused damage to the cell envelope of these intact cells and to the cytoplasmic membrane of E. coli spheroplasts. The damage to the cytoplasmic membrane was manifested in the release of 260-nm absorbing material and β-galactosidase from the spheroplasts, and by increased permeability of cryptic cells to O -nitrophenyl-β- d -galactopyranoside; damage to the cell wall was measured by release of alkaline phosphatase. Microscope observation showed morphological changes in the cell envelope.

scholarly journals Histidine-Rich Glycoprotein Inhibits HIV-1 Infection in a pH-Dependent Manner

2018 ◽  
Vol 93 (4) ◽  
Author(s):  
Ezequiel Dantas ◽  
Fernando Erra Díaz ◽  
Pehuén Pereyra Gerber ◽  
Augusto Varese ◽  
Diana Alicia Jerusalinsky ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Respiratory Syncytial Virus ◽  
Herpes Simplex ◽  
Low Ph ◽  
Vaginal Mucosa ◽  
Ph Values ◽  
Syncytial Virus ◽  
Simplex Virus ◽  
Herpes Simplex Virus 2 ◽  
Hiv 1

ABSTRACTHistidine-rich glycoprotein (HRG) is an abundant plasma protein with a multidomain structure, allowing its interaction with many ligands, including phospholipids, plasminogen, fibrinogen, IgG antibodies, and heparan sulfate. HRG has been shown to regulate different biological responses, such as angiogenesis, coagulation, and fibrinolysis. Here, we found that HRG almost completely abrogated the infection of Ghost cells, Jurkat cells, CD4+T cells, and macrophages by HIV-1 at a low pH (range, 6.5 to 5.5) but not at a neutral pH. HRG was shown to interact with the heparan sulfate expressed by target cells, inhibiting an early postbinding step associated with HIV-1 infection. More importantly, by acting on the viral particle itself, HRG induced a deleterious effect, which reduces viral infectivity. Because cervicovaginal secretions in healthy women show low pH values, even after semen deposition, our observations suggest that HRG might represent a constitutive defense mechanism in the vaginal mucosa. Of note, low pH also enabled HRG to inhibit the infection of HEp-2 cells and Vero cells by respiratory syncytial virus (RSV) and herpes simplex virus 2 (HSV-2), respectively, suggesting that HRG might display broad antiviral activity under acidic conditions.IMPORTANCEVaginal intercourse represents a high-risk route for HIV-1 transmission. The efficiency of male-to-female HIV-1 transmission has been estimated to be 1 in every 1,000 episodes of sexual intercourse, reflecting the high degree of protection conferred by the genital mucosa. However, the contribution of different host factors to the protection against HIV-1 at mucosal surfaces remains poorly defined. Here, we report for the first time that acidic values of pH enable the plasma protein histidine-rich glycoprotein (HRG) to strongly inhibit HIV-1 infection. Because cervicovaginal secretions usually show low pH values, our observations suggest that HRG might represent a constitutive antiviral mechanism in the vaginal mucosa. Interestingly, infection by other viruses, such as respiratory syncytial virus and herpes simplex virus 2, was also markedly inhibited by HRG at low pH values, suggesting that extracellular acidosis enables HRG to display broad antiviral activity.

scholarly journals Effect of water temperature and pH on the concentration and time of ozone saturation

2018 ◽  
Vol 21 (0) ◽  
Author(s):  
Melicia Cintia Galdeano ◽  
Allan Eduardo Wilhelm ◽  
Isabella Borges Goulart ◽  
Renata Valeriano Tonon ◽  
Otniel Freitas-Silva ◽  
...  
Keyword(s):  
Water Temperature ◽  
Molecular Oxygen ◽  
Half Life ◽  
Low Ph ◽  
Ozone Content ◽  
Effect Of Temperature ◽  
Saturation Time ◽  
Gas Concentration ◽  
Ph Values ◽  
Effect Of Water

Abstract Ozone has been used for many years to disinfect water due to its oxidizing potential. Since it decomposes quickly into molecular oxygen, leaving no residue, it has important advantages for use. The decomposition of ozone is affected by the temperature and pH of the medium, low pH values and temperatures increasing its half-life, which can result in more efficient disinfection. With the objective of increasing the effectiveness of ozonation, this study investigated the effect of temperature (8 ºC and 25 °C) and pH (3.0 and 6.0) of the water on the saturation time and gas concentration, employing two initial gas concentrations (13.3 and 22.3 mg L-1). The concentration of ozone saturation increased as the temperature and pH of the medium decreased, as also with the higher initial gas concentration ( C0). The highest saturation concentrations were obtained at pH 3.0 and 8 °C (4.50 and 8.03 mg L-1 with C0 of 13.3 and 22.3 mg L-1, respectively). This higher ozone content could result in greater decontamination efficiency of the food products washed with this water.

Efficacy of Bisulfite Ions as an Oxygen Scavenger in Monoethylene Glycol (At Least 20 wt%)/Water Mixtures

SPE Journal ◽  
2017 ◽  
Vol 22 (05) ◽  
pp. 1467-1477 ◽  
Author(s):  
Mobin Salasi ◽  
Thunyaluk Pojtanabuntoeng ◽  
Sindee Wong ◽  
Marc Lehmann
Keyword(s):  
Transition Metal ◽  
Oxygen Removal ◽  
Low Ph ◽  
Experimental Results ◽  
Oxygen Scavenger ◽  
Ph Values ◽  
Oxygen Scavenging ◽  
Monoethylene Glycol

Summary This study investigates the oxygen-scavenging behavior of bisulfite ions in monoethylene glycol (MEG)/water mixtures at concentrations commonly found in gas-transportation pipelines. Temperatures and pH values were varied. The influence of transition-metal (TM) ions to catalyze the bisulfite oxygen scavenging was studied. Experimental results indicate that MEG significantly inhibits bisulfite oxygen removal, which is hindered at low pH values and, to some extent, temperature. TMs can accelerate the oxygen-scavenging reaction in pH-unadjusted solutions, although the rate was still lower than that of the pH-adjusted solutions. The possible mechanism for such behavior and industrial implications are discussed.

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