scholarly journals The Crystal Structure of Bacillus cereus HblL1

Toxins ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 253
Author(s):  
Harley L. Worthy ◽  
Lainey J. Williamson ◽  
Husam Sabah Auhim ◽  
Stephen H. Leppla ◽  
Inka Sastalla ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Molecular Docking ◽  
Bacillus Cereus ◽  
Pore Formation ◽  
Food Poisoning ◽  
The Other ◽  
Bacillus Cereus Sensu Lato

The Hbl toxin is a three-component haemolytic complex produced by Bacillus cereus sensu lato strains and implicated as a cause of diarrhoea in B. cereus food poisoning. While the structure of the HblB component of this toxin is known, the structures of the other components are unresolved. Here, we describe the expression of the recombinant HblL1 component and the elucidation of its structure to 1.36 Å. Like HblB, it is a member of the alpha-helical pore-forming toxin family. In comparison to other members of this group, it has an extended hydrophobic beta tongue region that may be involved in pore formation. Molecular docking was used to predict possible interactions between HblL1 and HblB, and suggests a head to tail dimer might form, burying the HblL1 beta tongue region.

scholarly journals Effect of infant meal home preparation temperature on surviving of Bacillus cereus sensu lato: A case of Bechar city, Algeria

2021 ◽  
Vol 25 (2) ◽  
pp. 201-210
Author(s):  
Hassiba Difallah ◽  
Mohammed Ziane ◽  
Olfa Ben Braïek ◽  
Mohammed Bouamra ◽  
Habiba Louzim
Keyword(s):  
Heat Resistance ◽  
Bacillus Cereus ◽  
Storage Conditions ◽  
The Other ◽  
Preparation Temperature ◽  
Meal Preparation ◽  
Production Preparation ◽  
And Storage ◽  
Bacterial Concentrations ◽  
Bacillus Cereus Sensu Lato

Abstract This work aimed to enumerate the Bacillus cereus sensu lato from infant’s flour sampled at Béchar city and evaluate its resistance to different heating conditions during meal preparation patterns at home. Our findings revealed a prevalence of 74% with 2.4 to 3.9 CFU/g in the analyzed samples. Regarding the heat resistance at 90 °C to 98 °C, our results showed heat resistance variability which depends on the isolate, for example, D90 °C and zT °C values varied from 3.24 to 5.52 min and 11.56 to 89.74 °C respectively. Then, the decimal reduction (n) was calculated at all preparation temperatures (50, 60, 70, 80, 90 and 100 °C). Low “n” was observed with the preparation at T≤50 °C as recommended by the fabricant. However, at the other temperatures, high “n” was observed at 100°C with median and 95th values of 2.22 and 12.36 respectively. Therefore, bacterial concentrations (99th) were estimated at 0.124 log CFU/g for 100 °C. These concentrations could be increased with bacterial growth during meal storage and then achieve critical concentrations. Thus, the results of this work highlight the interest to establish a risk assessment for babies and to improve the production, preparation, and storage conditions of the infant’s flour.

scholarly journals Binding to The Target Cell Surface Is The Crucial Step in Pore Formation of Hemolysin BL from Bacillus cereus

Toxins ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 281 ◽  
Author(s):  
Nadja Jessberger ◽  
Richard Dietrich ◽  
Stefanie Schwemmer ◽  
Franziska Tausch ◽  
Valerie Schwenk ◽  
...  
Keyword(s):  
Cell Surface ◽  
Bacillus Cereus ◽  
Target Cell ◽  
Mode Of Action ◽  
Pore Formation ◽  
Food Poisoning ◽  
Crucial Step ◽  
Sequential Binding ◽  
L1 And L2 ◽  
Hemolysin Bl

A major virulence factor involved in Bacillus cereus food poisoning is the three-component enterotoxin hemolysin BL. It consists of the binding component B and the two lytic components L1 and L2. Studying its mode of action has been challenging, as natural culture supernatants additionally contain Nhe, the second three-component enterotoxin, and purification of recombinant (r) Hbl components has been difficult. In this study, we report on pore-forming, cytotoxic, cell binding and hemolytic activity of recently generated rHbl components expressed in E. coli. It is known that all three Hbl components are necessary for cytotoxicity and pore formation. Here we show that an excess of rHbl B enhances, while an excess of rHbl L1 hinders, the velocity of pore formation. Most rapid pore formation was observed with ratios L2:L1:B = 1:1:10 and 10:1:10. It was further verified that Hbl activity is due to sequential binding of the components B - L1 - L2. Accordingly, all bioassays proved that binding of Hbl B to the cell surface is the crucial step for pore formation and cytotoxic activity. Binding of Hbl B took place within minutes, while apposition of the following L1 and L2 occurred immediately. Further on, applying toxin components simultaneously, it seemed that Hbl L1 enhanced binding of B to the target cell surface. Overall, these data contribute significantly to the elucidation of the mode of action of Hbl, and suggest that its mechanism of pore formation differs substantially from that of Nhe, although both enterotoxin complexes are sequentially highly related.

scholarly journals Studies on the heat resistance ofBacillus cereusspores and growth of the organism in boiled rice

1980 ◽  
Vol 84 (1) ◽  
pp. 77-82 ◽  
Author(s):  
Jennifer M. Parry ◽  
R. J. Gilbert
Keyword(s):  
Growth Rate ◽  
Heat Resistance ◽  
Bacillus Cereus ◽  
Food Poisoning ◽  
The Other ◽  
Cooked Rice ◽  
Serotype 1

SUMMARYA comparison was made of the heat resistance ofBacillus cereusspores at 95° C. Spores of serotype 1 strains were more resistant than those of the other types tested. However, there was little difference in the growth rate of the various serotypes in boiled rice at 22° C. Most samples of uncooked rice contained multiple serotypes ofB. cereus.These results indicate that the cooking procedure used for the preparation of cooked rice is likely to be selective for certain serotypes, and this is the most likely reason why type 1 is the most common serotype implicated in outbreaks of food poisoning and can be isolated from many routine samples of cooked rice.

Molecular Characterization and Risk Assessment of Bacillus cereus Sensu Lato Isolated from Ultrahigh-Temperature and Pasteurized Milk Marketed in Rio de Janeiro, Brazil

2017 ◽  
Vol 80 (7) ◽  
pp. 1060-1065 ◽  
Author(s):  
Jeane Q. Chaves ◽  
Eislaine P. de Paiva ◽  
Leon Rabinovitch ◽  
Adriana M. Vivoni
Keyword(s):  
Bacillus Cereus ◽  
Rio De Janeiro ◽  
Virulence Genes ◽  
Food Poisoning ◽  
Type I ◽  
Microbiological Analysis ◽  
Phylogenetic Groups ◽  
Pasteurized Milk ◽  
Ultrahigh Temperature ◽  
Bacillus Cereus Sensu Lato

ABSTRACT The presence of Bacillus cereus in milk is a major concern in the dairy industry. In this study 27 Bacillus cereus sensu lato isolates from pasteurized and ultrahigh-temperature (UHT) milk (24 whole UHT and 4 pasteurized samples) collected at supermarket chains in Rio de Janeiro, Brazil, were evaluated to assess the potential risk for food poisoning. Toxigenic and virulence profiles were defined by gene-specific PCR. Affiliation to phylogenetic groups was assigned by panC sequencing. Microbiological analysis revealed the presence of B. cereus s.l. in eight (33.3%) brands (six brands of UHT and two brands of pasteurized milk). Twenty-seven isolates were recovered (13 B. cereus and 14 Bacillus thuringiensis). Predominant toxigenic patterns were type I (contains all toxin genes except ces) and type II (does not contain cytK and ces), with seven (25.9%) isolates each. Predominant virulence patterns were type 2 (does not contain hlyII or shp) and type 3 (contains all virulence genes), with five (18.5%) isolates each. All isolates belonged to phylogenetic groups III and IV. Presence of hbl, piplc, and sph was associated with group IV isolates. Our results suggest that B. thuringiensis and B. cereus sensu stricto should be considered potential foodborne pathogens. Because the majority of the milk isolates studied have the potential to cause food poisoning because of the high prevalence of toxin and virulence genes and the specific phylogenetic group affiliations, these milk products can be potentially hazardous for human consumption.

KEJADIAN LUAR BIASA KERACUNAN “CUMI-CUMIAN” DI SEKOLAH DASAR NEGERI 1 TRASAN BANDONGAN KABUPATEN MAGELANG

2018 ◽  
Vol 7 (2) ◽  
pp. 131-136
Author(s):  
Nasir Ahmad
Keyword(s):  
Abdominal Pain ◽  
Bacillus Cereus ◽  
Rhodamine B ◽  
Attack Rate ◽  
Food Poisoning ◽  
Health Department ◽  
Analysis Data ◽  
Food Samples ◽  
Bivariate Analysis ◽  
School Committee

Background: On May 4th, 2016, at 12:30 district surveillance officer of Magelang Health Department received reports from Public Health Center of Bandongan about 21 students of SDN 1 Trasan who suffered from the same food-poisoning symptoms. Objective: Investigation was carried out to identify the source, how it spread and how to control it. Methods: This study used descriptive analytic and mapping the cases distribution location. The case was people experiencing symptoms of dizziness or abdominal pain or nausea or vomiting. Data analysis was done by using bivariate analysis. Data collection were done through interviews, observations and laboratory tests on the food samples. Results: The case was 50 students (from 1-6 grade students). The perceived symptoms were dizziness (77%), nausea (42%), abdominal pain (40%) and vomiting (8%). Attack rate found ranged from 14.3% to 60% with the highest Attack rate found on class three (60%). The incubation period of 15-240 minutes (mean 72.3 minutes). Calamari like positive Bacillus cereus and Rhodamine-B 10 mg/kg. Conclusion: The outbreak of food poisoning because calamari like contaminated Bacillus cereus. We suggested the school committee to provide the socialization of harmful food for the students. The teachers should restrict the permission for the food vendor to sell at school.   Keywords: Bacillus cereus, , Food Poisoning, Outbreak, Rhodamine B, School Food

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