scholarly journals Effects of Bile Acids and Nisin on the Production of Enterotoxin byClostridium perfringensin a Nutrient-Rich Medium

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Miseon Park ◽  
Fatemeh Rafii
Keyword(s):  
Bile Acids ◽  
Toxin Production ◽  
The United States ◽  
Watery Diarrhea ◽  
Rich Medium ◽  
Low Concentrations ◽  
Stress Signal ◽  
Nutrient Rich Medium ◽  
Spore Outgrowth ◽  
Early Growth Phase

Clostridium perfringensis the second most common cause of bacterial foodborne illness in the United States, with nearly a million cases each year.C. perfringensenterotoxin (CPE), produced during sporulation, damages intestinal epithelial cells by pore formation, which results in watery diarrhea. The effects of low concentrations of nisin and bile acids on sporulation and toxin production were investigated inC. perfringensSM101, which carries an enterotoxin gene on the chromosome, in a nutrient-rich medium. Bile acids and nisin increased production of enterotoxin in cultures; bile acids had the highest effect. Both compounds stimulated the transcription of enterotoxin and sporulation-related genes and production of spores during the early growth phase. They also delayed spore outgrowth and nisin was more inhibitory. Bile acids and nisin enhanced enterotoxin production in some but not all otherC. perfringensisolates tested. Low concentrations of bile acids and nisin may act as a stress signal for the initiation of sporulation and the early transcription of sporulation-related genes in some strains ofC. perfringens, which may result in increased strain-specific production of enterotoxin in those strains. This is the first report showing that nisin and bile acids stimulated the transcription of enterotoxin and sporulation-related genes in a nutrient-rich bacterial culture medium.

Hunting the eagle killer: A cyanobacterial neurotoxin causes vacuolar myelinopathy

Science ◽  
2021 ◽  
Vol 371 (6536) ◽  
pp. eaax9050
Author(s):  
Steffen Breinlinger ◽  
Tabitha J. Phillips ◽  
Brigette N. Haram ◽  
Jan Mareš ◽  
José A. Martínez Yerena ◽  
...  
Keyword(s):  
United States ◽  
Aquatic Vegetation ◽  
Southeastern United States ◽  
Hydrilla Verticillata ◽  
Toxin Production ◽  
The United States ◽  
Biosynthetic Gene Cluster ◽  
Biosynthetic Gene ◽  
Bald Eagles ◽  
Cyanobacterial Species

Vacuolar myelinopathy is a fatal neurological disease that was initially discovered during a mysterious mass mortality of bald eagles in Arkansas in the United States. The cause of this wildlife disease has eluded scientists for decades while its occurrence has continued to spread throughout freshwater reservoirs in the southeastern United States. Recent studies have demonstrated that vacuolar myelinopathy is induced by consumption of the epiphytic cyanobacterial species Aetokthonos hydrillicola growing on aquatic vegetation, primarily the invasive Hydrilla verticillata. Here, we describe the identification, biosynthetic gene cluster, and biological activity of aetokthonotoxin, a pentabrominated biindole alkaloid that is produced by the cyanobacterium A. hydrillicola. We identify this cyanobacterial neurotoxin as the causal agent of vacuolar myelinopathy and discuss environmental factors—especially bromide availability—that promote toxin production.

scholarly journals Spo0A Suppresses sin Locus Expression in Clostridioides difficile

mSphere ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Babita Adhikari Dhungel ◽  
Revathi Govind
Keyword(s):  
Diarrheal Disease ◽  
Toxin Production ◽  
The United States ◽  
Upstream Region ◽  
Pcr Analysis ◽  
Bacterial Cells ◽  
Master Regulator ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile is the leading cause of nosocomial infection and is the causative agent of antibiotic-associated diarrhea. The severity of the disease is directly associated with toxin production, and spores are responsible for the transmission and persistence of the organism. Previously, we characterized sin locus regulators SinR and SinR′ (we renamed it SinI), where SinR is the regulator of toxin production and sporulation. The SinI regulator acts as its antagonist. In Bacillus subtilis, Spo0A, the master regulator of sporulation, controls SinR by regulating the expression of its antagonist, sinI. However, the role of Spo0A in the expression of sinR and sinI in C. difficile had not yet been reported. In this study, we tested spo0A mutants in three different C. difficile strains, R20291, UK1, and JIR8094, to understand the role of Spo0A in sin locus expression. Western blot analysis revealed that spo0A mutants had increased SinR levels. Quantitative reverse transcription-PCR (qRT-PCR) analysis of its expression further supported these data. By carrying out genetic and biochemical assays, we show that Spo0A can bind to the upstream region of this locus to regulates its expression. This study provides vital information that Spo0A regulates the sin locus, which controls critical pathogenic traits such as sporulation, toxin production, and motility in C. difficile. IMPORTANCE Clostridioides difficile is the leading cause of antibiotic-associated diarrheal disease in the United States. During infection, C. difficile spores germinate, and the vegetative bacterial cells produce toxins that damage host tissue. In C. difficile, the sin locus is known to regulate both sporulation and toxin production. In this study, we show that Spo0A, the master regulator of sporulation, controls sin locus expression. Results from our study suggest that Spo0A directly regulates the expression of this locus by binding to its upstream DNA region. This observation adds new detail to the gene regulatory network that connects sporulation and toxin production in this pathogen.

Impact of Government Bailout on Banks’ Cost of Equity: Additional Evidence from the Financial Bailout of 2008–2009

2021 ◽  
Vol 24 (01) ◽  
pp. 2150003
Author(s):  
Daphne Wang ◽  
Robert Houmes ◽  
Thanh Ngo ◽  
Omar Esqueda
Keyword(s):  
Institutional Ownership ◽  
The United States ◽  
Matched Sample ◽  
Cost Of Equity ◽  
Troubled Asset Relief Program ◽  
Low Concentrations ◽  
The Government ◽  
The Cost ◽  
Relief Program ◽  
Robust Evidence

The Capital Purchase Program (CPP) was the first and most significant program under the Troubled Asset Relief Program (TARP) during 2008–2009 financial crisis. This study evaluates the effect of the CPP during this period on the cost of equity of 170 publicly listed banks in the United States that received funding. To control for the potential effects of endogeneity on our results, we use a propensity score matched sample of non-CPP banks. Using this approach, we document robust evidence that the liquidity provided by the government bailout reduced the cost of equity for recipient banks, especially for those banks that repaid their bailout funds in full. This decrease in the cost of equity is particularly significant for banks with high market-to-book ratios, low concentrations of institutional ownership, and those banks with at least one large blockholder. Our findings have important implications for the assessment of government bailout programs and the future regulation of financial institutions.

scholarly journals Assessment of the anti-virulence potential of extracts from four plants used in traditional Chinese medicine against multidrug-resistant pathogens

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Zhonghui Pu ◽  
Huaqiao Tang ◽  
Nana Long ◽  
Min Qiu ◽  
Mingxiang Gao ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Chinese Medicine ◽  
Biofilm Formation ◽  
Ethanol Extract ◽  
Quorum Quenching ◽  
Toxin Production ◽  
Multidrug Resistant ◽  
Virulence Potential ◽  
Low Concentrations ◽  
Multidrug Resistant Pathogens

Abstract Background Multidrug-resistant pathogens are resistant to many antibiotics and associated with serious infections. Amomum tsaoko Crevost et Lemaire, Sanguisorba officinalis, Terminalia chebula Retz and Salvia miltiorrhiza Bge, are all used in Traditional Chinese Medicine (TCM) against multidrug-resistant pathogens, and the purpose of this study was to evaluate the antibacterial and anti-virulence activity of extracts derived from them. Methods The antibacterial activity of ethanol and aqueous extracts from these four plants was examined against several multi-drug resistant bacterial strains, and their anti-virulence potential (including quorum quenching activity, biofilm inhibition, and blocking production of virulence factor δ-toxin) was assessed against different S. aureus strains. The chemical composition of the most effective extract was determined by LC-FTMS. Results Only extracts from S. officinalis and A. tsaoko were shown to exhibit limited growth inhibition activity at a dose of 256 μg·mL-1. The S. officinalis ethanol extract, the ethanol and aqueous extract of A. tsaoko, and the aqueous extract of S. miltiorrhiza all demonstrated quorum quenching activity, but didn’t significantly inhibit bacterial growth. The ethanol extract of S. officinalis inhibited bacterial toxin production and biofilm formation at low concentrations. Chemical composition analysis of the most effective extract of S. officinalis showed that it mainly contained saponins. Conclusions The most active extract tested in this study was the ethanol root extract of S. officinalis. It inhibited δ-toxin production and biofilm formation at low concentrations and saponins may be its key active components. While the four plants showed no direct antibacterial effects, their anti-virulence properties may be key to fighting bacterial infections.

scholarly journals Stability-Indicating Photochemical Method for the Assay of Thiamine by Spectrophotometry

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Iqbal Ahmad ◽  
Syed Haider Abbas ◽  
Zubair Anwar ◽  
Muhammad Ali Sheraz ◽  
Sofia Ahmed ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
The United States ◽  
Limit Of Quantification ◽  
Chromatography Method ◽  
Stability Indicating ◽  
Low Concentrations ◽  
Photochemical Method ◽  
Significant Difference ◽  
Liquid Chromatography Method ◽  
States Pharmacopeia

A stability-indicating photochemical method has been developed for the assay of thiamine (TH) salts in aqueous solution and in fresh and aged vitamin preparations. It is based on the photooxidation of TH by UV irradiation to form thiochrome (TC) in alkaline solution. The TC : TH ratio under controlled conditions of light intensity, temperature, pH, exposure time, and irradiation distance is constant and can be used to determine the concentration of UV irradiated TH solutions. TC, on extraction with isobutanol from the photodegraded solution of TH, has been determined by the UV spectrophotometric method at 370 nm. It exhibits a high intensity of absorption in the UV region that can be used for the assay of even low concentrations of TH. Under optimum conditions, Beer’s law is obeyed in the concentration range of 0.20–2.00 mg/100 ml (R2 = 09998). The limit of detection (LOD) and limit of quantification (LOQ) are 0.0076 and 0.0231 mg/100 ml, respectively. The method has been validated and applied to aqueous solutions and vitamin preparations. The results have statistically been compared with the United States Pharmacopeia liquid chromatography method. It has been found that there is no significant difference between the two methods at 95% confidence level.

scholarly journals Rathayibacter toxicus, Other Rathayibacter Species Inducing Bacterial Head Blight of Grasses, and the Potential for Livestock Poisonings

2017 ◽  
Vol 107 (7) ◽  
pp. 804-815 ◽  
Author(s):  
Timothy D. Murray ◽  
Brenda K. Schroeder ◽  
William L. Schneider ◽  
Douglas G. Luster ◽  
Aaron Sechler ◽  
...  
Keyword(s):  
United States ◽  
Infected Plant ◽  
Extracellular Polysaccharide ◽  
Toxin Production ◽  
The United States ◽  
Diagnostic Methods ◽  
Extracellular Polysaccharides ◽  
Head Blight ◽  
Dry Conditions ◽  
Infected Plant Material

Rathayibacter toxicus, a Select Agent in the United States, is one of six recognized species in the genus Rathayibacter and the best known due to its association with annual ryegrass toxicity, which occurs only in parts of Australia. The Rathayibacter species are unusual among phytopathogenic bacteria in that they are transmitted by anguinid seed gall nematodes and produce extracellular polysaccharides in infected plants resulting in bacteriosis diseases with common names such as yellow slime and bacterial head blight. R. toxicus is distinguished from the other species by producing corynetoxins in infected plants; toxin production is associated with infection by a bacteriophage. These toxins cause grazing animals feeding on infected plants to develop convulsions and abnormal gate, which is referred to as “staggers,” and often results in death of affected animals. R. toxicus is the only recognized Rathayibacter species to produce toxin, although reports of livestock deaths in the United States suggest a closely related toxigenic species may be present. A closely related but undescribed species, Rathayibacter sp. EV, originally isolated from Ehrharta villosa var. villosa in South Africa, is suspected of producing toxin. Many of the diseases caused by Rathayibacter species occur in arid areas and the extracellular polysaccharide they produce is believed to aid in their survival between crops. For example, R. “agropyri” was isolated from infected plant material after being stored for 50 years in a herbarium. Similarly, the anguinid vectors associated with these bacteria form seed galls in infected plants and are capable of surviving for very long periods of time under dry conditions. The addition of R. toxicus to the list of Select Agents has raised concern over its potential introduction and a realization that current diagnostic methods are inadequate to distinguish among Rathayibacter species. In addition, little is known about the Rathayibacter species and their seed gall nematode vectors present in the United States.

Electrochemical Corrosion Behavior of Cu-15Ni-8Sn Alloy in Marine Microbial Medium

2009 ◽  
Vol 79-82 ◽  
pp. 1099-1102
Author(s):  
Yan Hua Lei ◽  
Yan Sheng Yin ◽  
Chao Hong Liu ◽  
Xue Ting Chang ◽  
Yan Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Electrochemical Corrosion ◽  
Rich Medium ◽  
Sem Images ◽  
Electrochemical Corrosion Behavior ◽  
Nutrient Rich Medium ◽  
Simulated Seawater ◽  
Control Samples ◽  
Scanning Electron

A comparative study of the corrosion behavior of the copper-nickel-tin alloy in a nutrient–rich simulated seawater-based nutrient-rich medium in the presence and the absence of the marine bacteria was carried out by electrochemical experiments, microscopic methods. Comparing to the corresponding control samples, the electrochemical data demonstrated that the presence of the bacteria accelerated the corrosion of the alloy. Scanning electron microscopy (SEM) images revealed the occurrence of micro-pitting and intergranular corrosion underneath the biofilm on the alloy surface.

scholarly journals Thermococcus kodakarensis Genetics: TK1827-Encoded β-Glycosidase, New Positive-Selection Protocol, and Targeted and Repetitive Deletion Technology

2009 ◽  
Vol 76 (4) ◽  
pp. 1044-1052 ◽  
Author(s):  
Thomas J. Santangelo ◽  
L'ubomíra Čuboňová ◽  
John N. Reeve
Keyword(s):  
Positive Selection ◽  
Reporter Gene ◽  
Half Life ◽  
Rich Medium ◽  
Thermococcus Kodakarensis ◽  
Optimal Activity ◽  
Glycosidase Activity ◽  
Nonessential Gene ◽  
Selection Protocol ◽  
Nutrient Rich Medium

ABSTRACT Inactivation of TK1761, the reporter gene established for Thermococcus kodakarensis, revealed the presence of a second β-glycosidase that we have identified as the product of TK1827. This enzyme (pTK1827) has been purified and shown to hydrolyze glucopyranoside but not mannopyranoside, have optimal activity at 95°C and from pH 8 to 9.5, and have a functional half-life of ∼7 min at 100°C. To generate a strain with both TK1761 and TK1827 deleted, a new selection/counterselection protocol has been developed, and the levels of β-glycosidase activity in T. kodakarensis strains with TK1761 and/or TK1827 deleted and with these genes expressed from heterologous promoters are described. Genetic tools and strains have been developed that extend the use of this selection/counterselection procedure to delete any nonessential gene from the T. kodakarensis chromosome. Using this technology, TK0149 was deleted to obtain an agmatine auxotroph that grows on nutrient-rich medium only when agmatine is added. Transformants can therefore be selected rapidly, and replicating plasmids can be maintained in this strain growing in rich medium by complementation of the TK0149 deletion.

Evaluation of White-Testa Peanut Genotypes for Potential Use As Food Supplements1

1978 ◽  
Vol 5 (2) ◽  
pp. 75-77 ◽  
Author(s):  
E. J. Conkerton ◽  
E. D. Blanchet ◽  
R. L. Ory ◽  
R. O. Hammons
Keyword(s):  
Calcium Content ◽  
The United States ◽  
Initial Study ◽  
Production Costs ◽  
Protein Supplements ◽  
Electrophoretic Patterns ◽  
Arachis Hypogaea L ◽  
Low Concentrations ◽  
High Calcium ◽  
Biochemical Profiles

Abstract While searching for peanut (Arachis hypogaea L.) genotypes that could compete both nutritionally and economically with other plant proteins in the United States market, a white-testa peanut was examined. This genotype had low concentrations of flatus-producing sugars, lacked flavor, and had a high calcium content. Production costs could be reduced because blanching would not be required to produce a high quality, cream-colored flour. Since the initial study, samples of four additional white-testa genotypes have been obtained. All five were examined for possible use as protein supplements in food. Flours and isolates were prepared and evaluated chemically for protein content, amino acid pattern, and gel- and immuno-electrophoretic patterns. Experimental field plots were grown to determine seed germination potentials and yields. The results indicated that two of the genotypes had good biochemical profiles and produced well in the field. These two Spanwhite and P. I. 288160. have been selected for further study.

Sign in / Sign up

Export Citation Format

Share Document