Biological characteristics of an enterotoxin produced by Bacillus cereus

1975 ◽  
Vol 21 (8) ◽  
pp. 1236-1246 ◽  
Author(s):  
W. M. Spira ◽  
J. M. Goepfert
Keyword(s):  
Ionic Strength ◽  
Bacillus Cereus ◽  
Exponential Growth ◽  
Biological Activities ◽  
Egg Yolk ◽  
Immune Serum ◽  
Fluid Accumulation ◽  
Ileal Loop ◽  
Receptor Sites ◽  
Ph Range

An enterotoxin synthesized during exponential growth by Bacillus cereus produces fluid accumulation in rabbit ileal loops, alters vascular permeability in the skin of rabbits, and kills mice when injected intravenously. All activities are eluted simultaneously from a Sephadex G-75 column and are distinct from the hemolysin and egg yolk turbidity factor of B. cereus. The enterotoxin is a true exotoxin. It interacts with intestinal receptor sites in a highly transient manner in the ileal loop system. Rabbit immune serum produced against the culture fluids from one strain of B. cereus neutralized the three biological activities in all other strains tested except strain B-6-ac for which none of the activities were neutralized.Enterotoxin proved to be unstable under a wide variety of conditions; ionic strength was especially critical. Enterotoxin was most stable in a pH range of 5.0 to 10.0, but lost activity rapidly outside this range. Alkylation provided some protection of enterotoxin activity in crude preparations but failed to protect activity during purification procedures. It did not appear to affect critically the enterotoxin molecule itself, since elution profiles on Sephadex G-75 chromatography were unchanged after alkylation.

scholarly journals Incidence and characterisation of Bacillus cereus bacteriophages from Thua Nao, a Thai fermented soybean product

2021 ◽  
Vol 12 (1) ◽  
pp. 85-93
Author(s):  
Wallapat Phongtang ◽  
Ekachai Chukeatirote
Keyword(s):  
Bacillus Cereus ◽  
Food Industry ◽  
Pathogenic Bacteria ◽  
Morphological Analysis ◽  
Food Poisoning ◽  
Fermented Soybean ◽  
Foodborne Pathogenic Bacteria ◽  
Ph Range ◽  
Potential Use

Abstract Bacillus cereus is considered to be an important food poisoning agent causing diarrhea and vomiting. In this study, the occurrence of B. cereus bacteriophages in Thai fermented soybean products (Thua Nao) was studied using five B. cereus sensu lato indicator strains (four B. cereus strains and one B. thuringiensis strain). In a total of 26 Thua Nao samples, there were only two bacteriophages namely BaceFT01 and BaceCM02 exhibiting lytic activity against B. cereus. Morphological analysis revealed that these two bacteriophages belonged to the Myoviridae. Both phages were specific to B. cereus and not able to lyse other tested bacteria including B. licheniformis and B. subtilis. The two phages were able to survive in a pH range between 5 and 12. However, both phages were inactive either by treatment of 50°C for 2 h or exposure of UV for 2 h. It should be noted that both phages were chloroform-insensitive, however. This is the first report describing the presence of bacteriophages in Thua Nao products. The characterization of these two phages is expected to be useful in the food industry for an alternative strategy including the potential use of the phages as a biocontrol candidate against foodborne pathogenic bacteria.

scholarly journals Potentiating Effect of Mandelate and Lactate on Chemically Induced Germination in Members of Bacillus cereus Sensu Lato

2017 ◽  
Vol 83 (24) ◽  
Author(s):  
Alistair H. Bishop
Keyword(s):  
Bacillus Cereus ◽  
Large Scale ◽  
Germination Rate ◽  
Dependent Manner ◽  
Clostridium Sporogenes ◽  
Specific Chemical ◽  
Content Type ◽  
Ph Range ◽  
Significant Discovery ◽  
The Impact

ABSTRACT Endospores of the genus Bacillus can be triggered to germinate by a limited number of chemicals. Mandelate had powerful additive effects on the levels and rates of germination produced in non-heat-shocked spores of Bacillus anthracis strain Sterne, Bacillus cereus, and Bacillus thuringiensis when combined with l-alanine and inosine. Mandelate had no germinant effect on its own but was active with these germinants in a dose-dependent manner at concentrations higher than 0.5 mM. The maximum rate and extent of germination were produced in B. anthracis by 100 mM l-alanine with 10 mM inosine; this was equaled by just 25% of these germinants when supplemented with 10 mM mandelate. Half the maximal germination rate was produced by 40% of the optimum germinant concentrations or 15% of them when supplemented with 0.8 mM mandelate. Germination rates in B. thuringiensis were highest around neutrality, but the potentiating effect of mandelate was maintained over a wider pH range than was germination with l-alanine and inosine alone. For all species, lactate also promoted germination in the presence of l-alanine and inosine; this was further increased by mandelate. Ammonium ions also enhanced l-alanine- and inosine-induced germination but only when mandelate was present. In spite of the structural similarities, mandelate did not compete with phenylalanine as a germinant. Mandelate appeared to bind to spores while enhancing germination. There was no effect when mandelate was used in conjunction with nonnutrient germinants. No effect was produced with spores of Bacillus subtilis, Clostridium sporogenes, or C. difficile. IMPORTANCE The number of chemicals that can induce germination in the species related to Bacillus cereus has been defined for many years, and they conform to specific chemical types. Although not a germinant itself, mandelate has a structure that is different from these germination-active compounds, and its addition to this list represents a significant discovery in the fundamental biology of spore germination. This novel activity may also have important applied relevance given the impact of spores of B. cereus in foodborne disease and B. anthracis as a threat agent. The destruction of spores of B. anthracis, for example, particularly over large outdoor areas, poses significant scientific and logistical problems. The addition of mandelate and lactate to the established mixtures of l-alanine and inosine would decrease the amount of the established germinants required and increase the speed and level of germination achieved. The large-scale application of “germinate to decontaminate” strategy may thus become more practicable.

scholarly journals Detection of presumptive Bacillus cereus in the Irish dairy farm environment

2016 ◽  
Vol 55 (2) ◽  
pp. 145-151 ◽  
Author(s):  
A. O’Connell ◽  
E.M. Lawton ◽  
D. Leong ◽  
P. Cotter ◽  
D. Gleeson ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Ribosomal Rna ◽  
Gel Electrophoresis ◽  
Tap Water ◽  
Dairy Farm ◽  
Egg Yolk ◽  
Pulsed Field Gel Electrophoresis ◽  
Chromogenic Medium ◽  
Rrna Sequencing ◽  
Bulk Tank

AbstractThe objective of the study was to isolate potentialBacillus cereussensu lato (B.cereus s.l.)from a range of farm environments. Samples of tap water, milking equipment rinse water, milk sediment filter, grass, soil and bulk tank milk were collected from 63 farms. In addition, milk liners were swabbed at the start and the end of milking, and swabs were taken from cows’ teats prior to milking. The samples were plated on mannitol egg yolk polymyxin agar (MYP) and presumptiveB. cereus s.l. colonies were isolated and stored in nutrient broth with 20% glycerol and frozen at -80 °C. These isolates were then plated on chromogenic medium (BACARA) and colonies identified as presumptiveB. cereus s.l. on this medium were subjected to 16S ribosomal RNA (rRNA) sequencing. Of the 507 isolates presumed to beB. cereus s.l. on the basis of growth on MYP, only 177 showed growth typical ofB. cereus s.l. on BACARA agar. The use of 16S rRNA sequencing to identify isolates that grew on BACARA confirmed that the majority of isolates belonged toB. cereus s.l. A total of 81 of the 98 isolates sequenced were tentatively identified as presumptiveB. cereus s.l. Pulsed-field gel electrophoresis was carried out on milk and soil isolates from seven farms that were identified as having presumptiveB. cereus s.l. No pulsotype was shared by isolates from soil and milk on the same farm. PresumptiveB. cereus s.l. was widely distributed within the dairy farm environment.

Validation and Analysis of Modeled Predictions of Growth of Bacillus cereus Spores in Boiled Rice

2000 ◽  
Vol 63 (2) ◽  
pp. 268-272 ◽  
Author(s):  
DANA M. McELROY ◽  
LEE-ANN JAYKUS ◽  
PEGGY M. FOEGEDING
Keyword(s):  
Growth Rate ◽  
Bacillus Cereus ◽  
Exponential Growth ◽  
Generation Time ◽  
Time Lag ◽  
Lag Phase ◽  
Exponential Growth Rate ◽  
Phase Duration ◽  
Margin Of Safety ◽  
Fail Safe

The growth of psychrotrophic Bacillus cereus 404 from spores in boiled rice was examined experimentally at 15, 20, and 30°C. Using the Gompertz function, observed growth was modeled, and these kinetic values were compared with kinetic values for the growth of mesophilic vegetative cells as predicted by the U.S. Department of Agriculture's Pathogen Modeling Program, version 5.1. An analysis of variance indicated no statistically significant difference between observed and predicted values. A graphical comparison of kinetic values demonstrated that modeled predictions were “fail safe” for generation time and exponential growth rate at all temperatures. The model also was fail safe for lag-phase duration at 20 and 30°C but not at l5°C. Bias factors of 0.55, 0.82, and 1.82 for generation time, lag-phase duration, and exponential growth rate, respectively, indicated that the model generally was fail safe and hence provided a margin of safety in its growth predictions. Accuracy factors of 1.82, 1.60, and 1.82 for generation time, lag-phase duration, and exponential growth rate, respectively, quantitatively demonstrated the degree of difference between predicted and observed values. Although the Pathogen Modeling Program produced reasonably accurate predictions of the growth of psychrotrophic B. cereus from spores in boiled rice, the margin of safety provided by the model may be more conservative than desired for some applications. It is recommended that if microbial growth modeling is to be applied to any food safety or processing situation, it is best to validate the model before use. Once experimental data are gathered, graphical and quantitative methods of analysis can be useful tools for evaluating specific trends in model prediction and identifying important deviations between predicted and observed data.

Inactivation of Bacillus cereus ATCC 14579 Spore on Garlic with Combination Treatments of Germinant Compounds and Superheated Steam

2019 ◽  
Vol 82 (4) ◽  
pp. 691-695 ◽  
Author(s):  
YOUNGJE JO ◽  
HYERYEON BAE ◽  
SANG-SOON KIM ◽  
CHOONGJIN BAN ◽  
SANG OH KIM ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Food Industry ◽  
Superheated Steam ◽  
Egg Yolk ◽  
Weibull Model ◽  
Log Reduction ◽  
Combination Treatments ◽  
Treatment Conditions ◽  
Sublethal Injury ◽  
Time Required

ABSTRACT Garlic is one of the most popular spices in the food industry because of its unique flavor, aroma, and health benefits. However, garlic is easily contaminated by spore-forming Bacillus cereus from the soil. We studied inactivation of B. cereus spores using superheated steam (SHS) and germinant compounds such as l-alanine, inosine, and disodium 5′-inosinate. Treatment with SHS and germinant compounds (50 mM l-alanine plus 5 mM disodium inosine 5′-monophosphate) on B. cereus spores was more effective than SHS treatment alone. The inactivation trends were analyzed using the Weibull model, and a time required to achieve a 3-log reduction was determined. These values at 120°C after SHS and germinant compounds plus SHS were 2.14 and 1.26 min, respectively. In addition, SHS and germinant compounds plus SHS treatments inactivated B. cereus ATCC 14579 spores effectively without causing sublethal injury. Levels of inactivation of B. cereus spores enumerated on mannitol–egg yolk–polymyxin and overlaid with Brilliance Bacillus Cereus were not significantly different for all treatment conditions. Therefore, germinant compounds plus SHS treatment can be used effectively to control B. cereus ATCC 14579 spores on garlic. HIGHLIGHTS

scholarly journals Clostridium perfringens Delta-Toxin Damages the Mouse Small Intestine

Toxins ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 232 ◽  
Author(s):  
Soshi Seike ◽  
Masaya Takehara ◽  
Keiko Kobayashi ◽  
Masahiro Nagahama
Keyword(s):  
Epithelial Cells ◽  
Clostridium Perfringens ◽  
Intestinal Epithelial Cells ◽  
Cell Damage ◽  
Dependent Manner ◽  
Intestinal Epithelial ◽  
Fluid Accumulation ◽  
Ileal Loop ◽  
Junction Protein ◽  
E Cadherin

Clostridium perfringens strains B and C cause fatal intestinal diseases in animals. The secreted pore-forming toxin delta-toxin is one of the virulence factors of the strains, but the mechanism of intestinal pathogenesis is unclear. Here, we investigated the effects of delta-toxin on the mouse ileal loop. Delta-toxin caused fluid accumulation and intestinal permeability to fluorescein isothiocyanate (FITC)-dextran in the mouse ileal loop in a dose- and time-dependent manner. Treatment with delta-toxin induced significant histological damage and shortening of villi. Delta-toxin activates a disintegrin and metalloprotease (ADAM) 10, leading to the cleavage of E-cadherin, the epithelial adherens junction protein, in human intestinal epithelial Caco-2 cells. In this study, E-cadherin immunostaining in mouse intestinal epithelial cells was almost undetectable 1 h after toxin treatment. ADAM10 inhibitor (GI254023X) blocked the toxin-induced fluid accumulation and E-cadherin loss in the mouse ileal loop. Delta-toxin stimulated the shedding of intestinal epithelial cells. The shedding cells showed the accumulation of E-cadherin in intracellular vesicles and the increased expression of active caspase-3. Our findings demonstrate that delta-toxin causes intestinal epithelial cell damage through the loss of E-cadherin cleaved by ADAM10.

Why is the hydrolytic activity of acetylcholinesterase pH dependent? Kinetic study of acetylcholine and acetylthiocholine hydrolysis catalyzed by acetylcholinesterase from electric eel

2018 ◽  
Vol 73 (9-10) ◽  
pp. 345-351 ◽  
Author(s):  
Alena Komersová ◽  
Markéta Kovářová ◽  
Karel Komers ◽  
Václav Lochař ◽  
Alexander Čegan
Keyword(s):  
Catalytic Activity ◽  
Ionic Strength ◽  
Ph Value ◽  
Hydrolytic Activity ◽  
Initial Substrate ◽  
Electric Eel ◽  
Value Range ◽  
Ph Dependent ◽  
Ph Range ◽  
Initial Substrate Concentration

AbstractThe dependence of the activity of acetylcholinesterase from electric eel at a pH value range of 4.8–9.8 (phosphate buffer), regarding acetylcholine and acetylthiocholine hydrolysis, was determined at 25 °C, ionic strength of 0.11 M, and initial substrate concentration of 4 mM. At a pH range of 4.8–9.8, the dependencesA(pH) form a sigmoid increasing curve with the maximum catalytic activity at a pH range 8–9.5. For acetylcholine hydrolysis, the kinetic reason for such an increase inAconsists mainly of an increase in the rate constantk2(Michaelis-Menten) model with increasing pH of the reaction mixture. For acetylthiocholine hydrolysis, the kinetic explication of the determined dependenceA(pH) is more complicated.

Survival of Bacillus cereus Vegetative Cells and Spores during In Vitro Simulation of Gastric Passage

2012 ◽  
Vol 75 (4) ◽  
pp. 690-694 ◽  
Author(s):  
SIELE CEUPPENS ◽  
MIEKE UYTTENDAELE ◽  
KATRIEN DRIESKENS ◽  
ANDREJA RAJKOVIC ◽  
NICO BOON ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Acid Resistance ◽  
In Vitro Experiments ◽  
Vegetative Cells ◽  
Ph Values ◽  
Constant Ph ◽  
In Vitro Simulation ◽  
Ph Range

The enteric pathogen Bacillus cereus must survive gastric passage in order to cause diarrhea by enterotoxin production in the small intestine. The acid resistance and the survival after gastric passage were assessed by in vitro experiments with acidified growth medium and gastric simulation medium with B. cereus NVH 1230-88 vegetative cells and spores. First, batch incubations at constant pH values for 4 h, which represented different physiological states of the stomach, showed that spores were resistant to any gastric condition in the pH range of 2.0 to 5.0, while vegetative cells were rapidly inactivated at pH values of ≤4.0. Second, a dynamic in vitro gastric experiment was conducted that simulated the continuously changing in vivo conditions due to digestion dynamics by gradually decreasing the pH from 5.0 to 2.0 and fractional emptying of the stomach 30 to 180 min from the start of the experiment. All of the B. cereus spores and 14% (±9%) of the vegetative cells survived the dynamic simulation of gastric passage.

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