Effect of Sucrose Esters in Combination with Selected Mold Inhibitors on Growth and Aflatoxin Production by Aspergillus parasiticus1

1986 ◽  
Vol 49 (5) ◽  
pp. 378-382 ◽  
Author(s):  
DOUGLAS L. MARSHALL ◽  
LLOYD B. BULLERMAN
Keyword(s):  
Fold Increase ◽  
Aflatoxin Production ◽  
Sucrose Ester ◽  
Potassium Sorbate ◽  
Sucrose Esters ◽  
Inhibitory Effects ◽  
Ph Values ◽  
Inhibition Of Growth ◽  
Calcium Propionate ◽  
Low Levels

The effects of sucrose esterified with a mixture of palmitic and stearic acids (commonly referred to as sucrose ester) in combination with cinnamon, potassium sorbate, or calcium propionate on growth of and aflatoxin production by Aspergillus parasiticus was studied in broths at two pH values. Cinnamon in combination with sucrose ester did not result in additive or synergistic inhibitory effects on growth or aflatoxin production. At pH 4.0, subinhibitory amounts of cinnamon were stimulatory toward growth and antagonistic to inhibition of growth by sucrose ester. Complete inhibition of growth and aflatoxin production was observed with a cinnamon level of 1.0%, alone and in combination with sucrose ester. Low levels (0.1%) of calcium propionate or potassium sorbate combined with sucrose ester did not enhance inhibition of growth or aflatoxin production. A synergistic effect on inhibition of growth was observed with high levels of propionate or sorbate in combination with sucrose ester, while aflatoxin production remained relatively unaffected. However, subinhibitory levels of propionate resulted in a 10-fold increase of aflatoxin production and a shift in the ratio of aflatoxin B1 and G1, from 1:1 to 1:8. Subinhibitory levels of sorbate also caused a stimulation of aflatoxin production during the latter stages of incubation, though to a lesser degree than propionate.

Inhibition of Aflatoxin-Producing Fungi by Welsh Onion Extracts

1999 ◽  
Vol 62 (4) ◽  
pp. 414-417 ◽  
Author(s):  
J. J. FAN ◽  
J. H. CHEN
Keyword(s):  
Aspergillus Flavus ◽  
Mycelial Growth ◽  
Ethanol Extract ◽  
Aflatoxin Production ◽  
Inhibitory Effects ◽  
Welsh Onion ◽  
Extract Concentration ◽  
Ph Values ◽  
Ethanol Extracts ◽  
Yeast Extract Sucrose

Welsh onion ethanol extracts were tested for their inhibitory activity against the growth and aflatoxin production of Aspergillus flavus and A. parasiticus. The survival of spores of A. flavus and A. parasiticus depended on both the extract concentration and the exposure time of the spores to the Welsh onion extracts. The mycelial growth of two tested fungi cultured on yeast extract–sucrose broth was completely inhibited in the presence of the Welsh onion ethanol extract at a concentration of 10 mg/ml during 30 days of incubation at 25°C. The extracts added to the cultures also inhibited aflatoxin production at a concentration of 10 mg/ml or permitted only a small amount of aflatoxin production with extract concentration of 5 mg/ml after 2 weeks of incubation. Welsh onion ethanol extracts showed more pronounced inhibitory effects against the two tested aflatoxin-producing fungi than did the same added levels of the preservatives sorbate and propionate at pH values near 6.5.

Inhibitory Effects of Various Salts and/or Ionic Strengths on Growth from Clostridium botulinum 52A Spores or Vegetative Cells

1985 ◽  
Vol 48 (5) ◽  
pp. 421-428 ◽  
Author(s):  
M. K. WAGNER ◽  
F. F. BUSTA
Keyword(s):  
Ionic Strength ◽  
Clostridium Botulinum ◽  
Potassium Sorbate ◽  
Chloride Salt ◽  
Inhibitory Effects ◽  
Vegetative Cells ◽  
Inhibition Of Growth ◽  
The Mean ◽  
Ph Level ◽  
Peptone Yeast Extract Glucose

Growth response from spores and vegetative cells of Clostridium botulinum strain 52A in peptone-yeast extract-glucose (PYEG) broth at two pH levels (5.55 or 5.85) containing sodium acid pyrophosphate (SAPP) (0, 0.2, 0.4%), NaCl (0, 1.25, 2.50%) and/or potassium sorbate (KS) (0, 0.13, 0.26%) was measured as the mean A630 nm of 20 tubes at 37°C. Additional treatments contained KC1 and MgCl2 (0, 1.25, 2.50%) without SAPP or KS. Growth ratios (GR = treatment/control) based on time to reach A630 = 0.35 were calculated to compare effects of additives on strain 52A. Growth from spores was affected significantly (p≤0.01) by pH level. KS and KS/pH interactions were also significant factors in growth from both spores and vegetative cells; SAPP/pH interactions were significant for cell growth, only. Combinations of SAPP (0.2, 0.4%) NaCl (0%) and KS (0.26%) were the most favorable treatments for delaying growth from spores or vegetative cells. NaCl (1.25, 2.50%) decreased antibotulinal effects produced by combinations of SAPP and KS. Elimination of NaCl enhanced antibotulinal effects. Formulations containing KC1 or MgCl2 (without SAPP and KS) at the same molarity as the NaCl in earlier treatments (0.21, 0.43) resulted in inhibition of growth from vegetative cells greater than growth from spores in the presence of MgCl2 at M = 0.43 (ionic strength = 1.29). This inhibition was more evident at pH 5.55 than pH 5.85. This study in a model system suggests ionic strength and/or chloride salt may be important considerations when manipulating formulations of additives designed to control C. botulinum growth.

Effects of chromium and manganese on Thiobacillus ferrooxidans

1982 ◽  
Vol 28 (5) ◽  
pp. 536-544 ◽  
Author(s):  
Chen Wong ◽  
Marvin Silver ◽  
Donn J. Kushner
Keyword(s):  
Thiobacillus Ferrooxidans ◽  
Environmental Concern ◽  
Iron Oxidation ◽  
Ionic Concentration ◽  
Inhibitory Effects ◽  
Ph Values ◽  
Inhibition Of Growth ◽  
Ferrous Iron Oxidation ◽  
Chromite Concentrate ◽  
Osmotic Effects

Growth of Thiobacillus ferrooxidans at pH 2.5 is inhibited by concentrations of Cr2(SO4)3 greater than 1.5 × 10−2 M or by concentrations of MnSO4 greater than 0.6 M. Ferrous iron oxidation is less sensitive than growth to the inhibitory effects of Cr2(SO4)3 and MnSO4, and these inhibitions are greater at higher pH values. The inhibition of growth and iron oxidation by MnSO4 appears to be due only to general osmotic effects rather than to the specific ionic concentration. Growth of Escherichia coli is inhibited by 10−4 M K2Cr2O7 or by 2.4 × 10−2 M MnSO4. Although T. ferrooxidans causes the solubilization of chromium from a chromite concentrate to a maximum of 140 mg/L, this action may not be sufficient for commercial exploitation but may be sufficient for environmental concern.

Potassium Sorbate Inhibition of Microorganisms Isolated from Seafood1

1982 ◽  
Vol 45 (14) ◽  
pp. 1310-1313 ◽  
Author(s):  
YUH-MEI CHUNG ◽  
J. S. LEE
Keyword(s):  
Inhibitory Concentration ◽  
Basal Medium ◽  
Inhibitory Effect ◽  
Potassium Sorbate ◽  
Inhibitory Effects ◽  
Freeze Thaw ◽  
Inhibition Of Growth ◽  
Heat Treated ◽  
Lag Period ◽  
Logarithmic Growth

Microorganisms isolated from seafood showed various degrees of sensitivity toward potassium sorbate (PS). At pH 7.0, PS concentration of 0.53% completely inhibited growth of Moraxella sp., while 2.73% was needed to inhibit Arthrobacter sp. Pseudomonas I sp., which was relatively resistant to PS (inhibitory concentration = 1.62%), was not affected by 0.3% PS after freeze-thaw treatment (−78°C for 8 min and 20°C for 20 min), but showed a delay in onset of logarithmic growth for up to 20 h after heating at 50°C for 5 min. The inhibitory effect of PS on sub-lethally injured Pseudomonas I was greater in basal medium (Minimum Broth, Davis) than in a rich medium (tryptone-peptone-extract, TPE). Alteromonas putrefaciens, which was sensitive to PS (inhibitory concentration = 0.74%), was also sensitive to freeze-thaw and mild heat. The lag period for quick-frozen cells was extended by 14 h in the presence of 0.05% PS. Heating at 45°C for 10 sec was sufficient to cause complete inhibition of growth by 0.05% PS in MBD, and 8 h delay in the onset of logarithmic growth in TPE. Selective and inhibitory effects of PS, therefore, could be further enhanced in frozen or heat-treated seafood.

Growth and Aflatoxin Production by Aspergillus parasiticus NRRL 2999 in the Presence of Potassium Benzoate or Potassium Sorbate and at Different Initial pH Values

1987 ◽  
Vol 50 (10) ◽  
pp. 820-825 ◽  
Author(s):  
GULAM RUSUL ◽  
ELMER H. MARTH
Keyword(s):  
High Performance ◽  
Aspergillus Parasiticus ◽  
Ph Value ◽  
Aflatoxin Production ◽  
Reversed Phase ◽  
Potassium Sorbate ◽  
Lag Phase ◽  
Ph Values ◽  
Initial Ph ◽  
Potassium Benzoate

Experiments were done to determine how different concentrations of potassium benzoate or potassium sorbate in a glucose-yeast extract-salts medium with an initial pH value of 3.5, 4.5 or 5.5 affected growth and aflatoxin production by Aspergillus parasiticus NRRL 2999. The pH of the medium, weight of mycelium and amount of aflatoxin produced were determined after 3 and 7 d of incubation. Aflatoxin was determined using reversed-phase high-performance liquid chromatography. Maximum concentrations of potassium sorbate and potassium benzoate that permitted growth were 0.2% and 0.4%, respectively, in a medium with an initial pH of 5.5. When the initial pH was 4.5, the maximum concentrations of potassium sorbate and potassium benzoate that permitted growth were 0.05% and 0.10%, respectively, but there was an extended lag phase. Increasing concentrations of potassium benzoate or potassium sorbate decreased amounts of aflatoxin B1 and G1 produced after 3 d in a medium with initial pH values of 5.5 or 4.5. Cultures growing in the medium containing 0.1, 0.15 or 0.20% potassium benzoate or potassium sorbate and with an initial pH of 5.5 were somewhat inhibited at 3 d of incubation, which was characterized by a slow decrease in pH, low mycelium dry weight and small amounts of accumulated aflatoxins. After 7 d these cultures overcame the initial inhibition and produced substantial amounts of aflatoxins and mycelium. This was also true for cultures growing in a medium with an initial pH of 4.5 and containing potassium benzoate or potassium sorbate. By decreasing the initial pH of the medium from 5.5 to 4.5, amounts of potassium benzoate or potassium sorbate required to achieve inhibition decreased by a factor of 10.

Is the Acidic pH of the External Auditory Canal Playing a Significant Role in the Treatment of Acute Otitis Externa?

2018 ◽  
Vol 69 (8) ◽  
pp. 2304-2305
Author(s):  
Oana Ruxandra Iana ◽  
Dragos Cristian Stefanescu ◽  
Viorel Zainea ◽  
Razvan Hainarosie
Keyword(s):  
External Auditory Canal ◽  
Otitis Externa ◽  
Proton Pumps ◽  
Acidic Ph ◽  
External Ear ◽  
Ph Values ◽  
The World ◽  
Subcutaneous Tissues ◽  
Low Levels ◽  
Value Changes

Variable pH values for skin have been reported in the literature, all within the acidic range, varying from 4.0 up to 7. 0. The origin of the acidic pH remains conjectural, and several factors have been incriminated with this role, such as eccrine and sebaceous secretions as well as proton pumps. Keeping low levels of pH prevents microbial dispersal as well as multiplication. The skin in the external auditory canal is also covered with this acidic mantle with antimicrobial value. Changes of pH in the external ear can lead to acute otitis externa. This condition is defined by the inflammation and infection of the cutaneous and subcutaneous tissues of the external auditory canal. 10% of the world�s population may suffer from acute otitis externa at least once in their lifetime. This paper aims to consolidate the relevance of an acidic pH in the healthy external ear and its relation to the pathogenesis and treatment of otitis externa through a prospective and interventional clinical study on 80 patients who presented to the outpatient department at Prof. Dr D. Hociota ENT Institute in Buch

Histone H1 expressed in Saccharomyces cerevisiae binds to chromatin and affects survival, growth, transcription, and plasmid stability but does not change nucleosomal spacing

1994 ◽  
Vol 14 (4) ◽  
pp. 2822-2835
Author(s):  
C Linder ◽  
F Thoma
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasmid Stability ◽  
Apparent Molecular Weight ◽  
Histone H1 ◽  
Expression Levels ◽  
Inhibition Of Growth ◽  
Gene Coding ◽  
Gal1 Promoter ◽  
Core Histones ◽  
Low Levels

Histone H1 is proposed to serve a structural role in nucleosomes and chromatin fibers, to affect the spacing of nucleosomes, and to act as a general repressor of transcription. To test these hypotheses, a gene coding for a sea urchin histone H1 was expressed from the inducible GAL1 promoter in Saccharomyces cerevisiae by use of a YEp vector for high expression levels (strain YCL7) and a centromere vector for low expression levels (strain YCL1). The H1 protein was identified by its inducibility in galactose, its apparent molecular weight, and its solubility in 5% perchloric acid. When YCL7 was shifted from glucose to galactose for more than 40 h to achieve maximal levels of H1, H1 could be copurified in approximately stoichiometric amounts with core histones of Nonidet P-40-washed nuclei and with soluble chromatin fractionated on sucrose gradients. While S. cerevisiae tolerated the expression of low levels of H1 in YCL1 without an obvious phenotype, the expression of high levels of H1 correlated with greatly reduced survival, inhibition of growth, and increased plasmid loss but no obvious change in the nucleosomal repeat length. After an initial induction, RNA levels for GAL1 and H1 were drastically reduced, suggesting that H1 acts by the repression of galactose-induced genes. Similar effects, but to a lower extent, were observed when the C-terminal tail of H1 was expressed.

Bacterial Spore Inhibition and Inactivation in Foods by Pressure, Chemical Preservatives, and Mild Heat

2000 ◽  
Vol 63 (11) ◽  
pp. 1503-1510 ◽  
Author(s):  
ADRIENNE E. H. SHEARER ◽  
C. PATRICK DUNNE ◽  
ANTHONY SIKES ◽  
DALLAS G. HOOVER
Keyword(s):  
Combined Treatment ◽  
Bacillus Coagulans ◽  
High Heat ◽  
Tomato Juice ◽  
Heat Processing ◽  
Sucrose Esters ◽  
Inhibitory Effects ◽  
Clostridium Sporogenes ◽  
Mild Heat ◽  
Pressure Chemical

Sucrose laurates, sucrose palmitate, sucrose stearates, and monolaurin (Lauricidin) were evaluated for inhibitory effects against spores of Bacillus sp., Clostridium sporogenes PA3679, and Alicyclobacillus sp. in a model agar system. The combined treatment of sucrose laurate, high hydrostatic pressure, and mild heat was evaluated on spores of Bacillus and Alicyclobacillus in foods. The minimum inhibitory concentrations of the sucrose esters were higher than that of Lauricidin for all spores tested in the model agar system, but Lauricidin was not the most readily suspended in the test media. The sucrose laurates and sucrose palmitate were more effective and more readily suspended than the sucrose stearates. A combined treatment of sucrose laurate (≤1.0%), 392 megaPascals (MPa) at 45°C for 10 to 15 min provided 3- to 5.5-log10 CFU/ml reductions from initial populations of 106 CFU/ml for Bacillus subtilis 168 in milk, Bacillus cereus 14579 in beef, Bacillus coagulans 7050 in tomato juice (pH 4.5), Alicyclobacillus sp. N1089 in tomato juice (pH 4.5), and Alicyclobacillus sp. N1098 in apple juice. The most notable change in the appearance of the products was temporary foaming during mixing of the sucrose laurate in the foods. The effect of sucrose laurate appeared to be inhibitory rather than lethal to the spores. The inhibitory effects observed on Bacillus and Alicyclobacillus spores by the combined treatment of pressure, mild heat, and sucrose laurate appear promising for food applications where alternatives to high heat processing are desired.

Inhibitory effects of catecholamines in canine cardiac Purkinje fibers

1976 ◽  
Vol 231 (5) ◽  
pp. 1415-1420 ◽  
Author(s):  
P Posner ◽  
EL Farrar ◽  
CR Lambert
Keyword(s):  
Negative Response ◽  
Chronotropic Effect ◽  
Inhibitory Effects ◽  
Purkinje Fibers ◽  
Spontaneous Rate ◽  
Negative Chronotropic Effect ◽  
Cardiac Purkinje Fibers ◽  
Wide Range ◽  
Low Levels

The effect of catecholamines over a wide range of concentrations was studied on 42K uptake and efflux, as well as on spontaneous rate in canine cardiac Purkinje fibers. Low levels of catecholamines (less than 10(-10) M epinephrine; less than 10(-9) M norepinephrine) decreased automaticity. This negative chronotropic effect was blocked by phentolamine and mimicked by phenylephrine. These low levels of epinephrine and norepinephrine also inhibited 42K uptake by Purkinje fibers but had no effect on 42K efflux. The inhibition of 42K uptake was blocked by phentolamine and verapamil and mimicked by phenylephrine. The data indicate an alpha-receptor-mediated negative response of rate and 42K uptake to low levels of catecholamine. The end result is discussed in terms of a competitive increase in the influx of Ca2+ rather than Na+ and an indirect inhibition of the Na+-K+ pump.

scholarly journals SHV-16, a β-Lactamase with a Pentapeptide Duplication in the Omega Loop

2001 ◽  
Vol 45 (9) ◽  
pp. 2480-2485 ◽  
Author(s):  
Corinne Arpin ◽  
Roger Labia ◽  
Catherine Andre ◽  
Cécile Frigo ◽  
Zoubida El Harrif ◽  
...  
Keyword(s):  
Clinical Isolate ◽  
Donor Cell ◽  
Fold Increase ◽  
Site Directed Mutagenesis ◽  
Resistance Pattern ◽  
E Coli ◽  
Omega Loop ◽  
Low Levels ◽  
Encoding Gene ◽  
Level Resistance

ABSTRACT A clinical isolate of Klebsiella pneumoniae was found to be resistant to ampicillin (MIC of 128 μg/ml), ticarcillin (MIC of 512 μg/ml), and ceftazidime (MIC of 128 μg/ml) and susceptible to all other β-lactams; a synergistic effect between clavulanate and ceftazidime suggested the presence of an extended-spectrum β-lactamase (ESBL). Transconjugants inEscherichia coli were obtained at low levels (10−7 per donor cell) and exhibited a similar β-lactam resistance pattern (resistant to ampicillin, ticarcillin, and ceftazidime at 64 μg/ml). The ESBL, pI 7.6, was encoded by a large plasmid (>100 kb) which did not carry any other resistance determinant. The ESBL-encoding gene was amplified by PCR usingbla SHV-specific primers and was sequenced. The deduced amino acid sequence of the SHV-16 ESBL showed that it differed from SHV-1 by only a pentapeptide insertion (163DRWET167) corresponding to a tandem duplication in the omega loop. The implication of the 163a-DRWET163b-DRWET sequence in ceftazidime resistance was confirmed by cloning either bla SHV-1 orbla SHV-16 in the same vector, subsequently introduced in the same E. coli strain. Under these isogenic conditions, SHV-16 conferred a 32-fold increase in ceftazidime MIC compared to that with SHV-1. Furthermore, site-directed mutagenesis experiments modifying either E166aA or E166bA revealed that the functional glutamic residue was that located in the first copy of the duplicated sequence. But surprisingly, the second E166b also conferred a low-level resistance to ceftazidime. This work is the first description of a class A enzyme exhibiting an extended substrate specificity due to an insertion instead of a nucleotide substitution(s) in a clinical isolate.

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