Bacillus Cereus

Abstract

Bacillus cereus is a spore forming bacterium that produces toxins that cause vomiting or diarrhoea. Symptoms are generally mild and short-lived (up to 24 hours). B. cereus is commonly found in the environment (e.g. soil) as well as a variety of foods. Spores are able to survive harsh environments including normal cooking temperatures. Description of the organism B. cereus is a Gram-positive, motile (flagellated), spore-forming, rod shaped bacterium that belongs to the Bacillus genus. Species within this genus include B. anthracis, B. cereus, B. mycoides, B. thuringiensis, B. pseudomycoides and B. weihenstephanensis (Rajkowski and Bennett 2003; Montville and Matthews 2005). Genomic sequencing data has shown B. anthracis, B. cereus and B. thuringiensis to be very closely related (Rasko et al. 2004) with their 16S rRNA gene sequence sharing more than 99% similarity (Ash et al. 1991). B. cereus is widespread in nature and readily found in soil, where it adopts a saprophytic life cycle; germinating, growing and sporulating in this environment (Vilain et al. 2006). Spores are more resistant to environmental stress than vegetative cells due to their metabolic dormancy and tough physical nature (Jenson and Moir 2003). B. cereus produces two types of toxins-emetic (vomiting) and diarrhoeal-causing two types of illness. The emetic syndrome is caused by emetic toxin produced by the bacteria during the growth phase in the food. The diarrhoeal syndrome is caused by diarrhoeal toxins produced during growth of the bacteria in the small intestine (Ehling-Schulz et al. 2006). Growth and survival characteristics Strains of B. cereus vary widely in their growth and survival characteristics (refer to Table 1). Isolates from food and humans can be subdivided as either mesophilic or psychrotrophic strains. Mesophilic strains grow well at 37°C but do not grow below 10°C; psychrotrophic strains grow well at refrigeration temperatures but grow poorly at 37°C (Wijnands et al. 2006a). All isolates of B. cereus associated with emetic toxin production have been found to be mesophilic in nature (Pielaat et al. 2005; Wijnands et al. 2006b).

Characterization of Bacillus cereus in Dairy Products in China

“…B. cereus prevails in soil and dairy farms and often pollutes foods like raw milk and all dairy products [ 3 , 71 ]. Spores of B. cereus can primarily spread through soil and air [ 69 ].…”

“…B. cereus is a ubiquitous Gram-positive, aerobic or facultative anaerobic, endospore-forming, rod-shaped bacterium [ 13 , 71 ]. The detection and isolation of B. cereus strains are mainly based on the colony count technique ISO 7932 [ 96 ].…”

Antibacterial Activity and Mode of Action of β-caryophyllene on Bacillus cereus

“…In more severe cases outside of the gastrointestinal tract, B. cereus causes nosocomial systemic infections in immunocompromised patients including bac te remia, cerebral abscess, endocarditis meningitis, pneumonia, and septicemia (Sankararaman and Velayuthan 2013). To better manage the risks of food spoilage, which caused significant economic losses in the food industry, there is the need to search not only for new compounds with antimicrobial activity but more importantly of low toxicity.…”

S-layer Impacts the Virulence ofBacillusin Endophthalmitis

“…The Bacillus cell envelope varies structurally from other Gram-positive ocular pathogens, such as staphylococci or streptococci 35–38. The envelopes of Bacillus and other Gram-positive organisms have an inner membrane, a thick layer of peptidoglycan (PGN), teichoic acids (TA), and lipoproteins (Lpp), and proteinaceous adhesive appendages called pili 38–42.…”