Next-Generation Whole-Genome Sequencing of Eight Strains of Bacillus cereus, Isolated from Food
ABSTRACT
Bacillus cereus can contaminate food and cause emetic and diarrheal foodborne illness. Here, we report whole-genome sequences of eight strains of B. cereus, isolated from different food sources.
GENOME ANNOUNCEMENT
Bacillus cereus is a mesophilic or psychrotrophic, spore-forming bacterium commonly present in soil (1). It occurs in the rhizosphere of plants (2, 3) and as a part of animal intestinal microflora (4). It is opportunistically pathogenic and leads to various infections, including: local infections of wounds, or an eye; bacteremia and septicemia; respiratory infections; central nervous system infections; pericarditis; and endocarditis (5). Due to its presence in soil and production of spores, B. cereus often contaminates various food products. Consumption of foods with high levels of B. cereus may result in two types of foodborne illness: emetic or diarrheal. The emetic type, characterized by vomiting and nausea, is induced by the cereulide toxin produced by cells growing in food (6–8). The diarrheal illness is caused by enterotoxins, including hemolysin BL, cytotoxin K, and nonhemolytic enterotoxin, which are produced by B. cereus cells in the small intestine (6, 7). B. cereus is closely related to Bacillus anthracis, the causative agent of anthrax, and to the insect pathogen, Bacillus thuringiensis (9).
Eight strains of B. cereus, isolated from different food sources were sequenced by next-generation whole-genome sequencing. The strains were grown at 30°C with shaking at 220 rpm in heart infusion (BHI) broth (Difco). The overnight cultures were diluted in fresh medium to the optical density at 600 nm (OD600) and harvested by centrifugation at 5,000 relative centrifugal force (RCF). Subsequently, total DNA was isolated by phenol-chloroform extraction as described previously (10). The isolated DNA was sheared to 500-bp fragments in the Covaris (KBioscience) ultrasone device for preparing the NGS library preps using the paired-end NEB NExtGen library preparation kit. The libraries were 101-base paired-end sequenced on an Illumina HiSeq2000. Subsequently, Velvet (11) was used to perform a de novo paired-end assembly on each genome resulting in the draft genome sequences. The RAST server (12) and BAGEL3 (13) were used to annotate the genomes and to identify putative bacteriocin gene clusters, respectively.
Nucleotide sequence accession numbers.
The genome sequence of the eight Bacillus cereus strains have been deposited as whole-genome shotgun projects at DDBJ/EMBL/GenBank under the accession numbers listed in Table 1.
TABLE 1
| B. cereus strain | Source | Accession no. |
|---|---|---|
| B4077 | Chilled dessert | LCYI00000000 |
| B4078 | Food, undefined | LCYJ00000000 |
| B4080 | Dried onion | LCYK00000000 |
| B4086 | Boiled rice | LCYL00000000 |
| B4087 | Pea soup | LCYM00000000 |
| B4147 | Cereals, pasta and pastries | LCYN00000000 |
| B4153 | Dairy products | LCYO00000000 |
| B4158 | Vegetables | LCYP00000000 |
a
B-numbers refer to the strain collection at NIZO food research and the University of Groningen (Molecular Genetics).
ACKNOWLEDGMENTS
We thank the NGS sequence facility of the University Medical Center of Groningen (UMCG) for performing the sequencing of the strains. We thank Top Institute for Food and Nutrition for contributing to the funding of the project in theme 3: Safety and Preservation.
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Information & Contributors
Information
Published In
Genome Announcements
Volume 3 • Number 6 • 31 December 2015
eLocator: 10.1128/genomea.01480-15
Copyright
© 2015 Krawczyk et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported license.
History
Received: 27 October 2015
Accepted: 27 October 2015
Published online: 17 December 2015
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