B. cereus growth is optimal in the presence of oxygen, but can occur under anaerobic conditions. cereus cells grown under aerobic conditions are less resistant to heat and acid than B. cereus cells grown anaerobically or microaerobically (Mols et al. Subsequently, one may also ask, is Bacillus anthracis
Bacillus anthracis
Bacillus anthracis is the etiologic agent of anthrax—a common disease of livestock and, occasionally, of humans—and the only obligate pathogen within the genus Bacillus. B. anthracis is a Gram-positive, endospore-forming, rod-shaped bacterium, with a width of 1.0–1.2 µm and a leng…
What are the benefits of Bacillus cereus?
In food animals such as chickens, rabbits and pigs, some harmless strains of B. cereus are used as a probiotic feed additive to reduce Salmonella in the animals' intestines and cecum. This improves the animals' growth, as well as food safety for humans who eat them. B. cereus can parasitize codling moth larvae.
Is Bacillus cereus aerobic or anaerobic?
Bacillus cereus (B. cereus) is classified as a gram-positive, aerobic or facultative anaerobic, spore former, motile, pathogenic, and opportunistic bacterium capable of producing resistant endospores in the presence of oxygen. B. cereus is widely distributed in the environment, namely soil, where spores persist under adverse conditions.
What is the relationship between Bacillus cereus and the complex?
Bacillus cereus is member of a group of closely related organisms, the B. cereus complex. Work aimed at understanding the relationships between members of the complex, and on their characteristics and mechanisms of pathogenicity, has been extensive.
Is Bacillus cereus a pathogen for the airways?
Bacillus cereus is a ubiquitously distributed environmental organism whose pathogenicity for airways is probably poorly taken into consideration in the medical setting but emerges from the published literature.
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Is Bacillus cereus aerobic or anaerobic?
Bacillus cereus is an aerobic spore-forming bacterium that is commonly found in soil, on vegetables, and in many raw and processed foods.
What does Bacillus cereus need to survive?
Bacillus cereus spores can germinate when exposed to heat or improper handling; therefore, the 2013 Food Code recommends that hot foods be maintained at a temperature of 135ºF (57ºC) or above and cold foods be maintained at a temperature of 41ºF (5ºC) or below (FDA 2013a).
Is Bacillus cereus an obligate anaerobe?
Abstract. The Gram-positive bacterium Bacillus cereus is a facultative anaerobe that is still poorly characterized metabolically.
Is Bacillus cereus oxidative or fermentative?
The occurrence of an oxidative component in response to oxygen deprivation has been confirmed in B. cereus by microarray studies on the whole genome level and by proteomic studies (Mols and Abee, 2011b; Clair et al., 2012; Madeira et al., 2015).
Can Bacillus cereus survive dehydration?
B. cereus in dehydrated potato is likely to be present as spores that are able to survive drying of the raw vegetable and may represent a significant inoculum in the reconstituted (rehydrated) product where conditions favor germination of, and outgrowth from, spores.
Does Bacillus cereus produce gas?
True Bacillus cereus can ferment glucose but it cannot ferment lactose; none of the fermentation reactions produce gas as well.
Do bacteria require oxygen to grow?
Oxygen. One of the most-prominent differences between bacteria is their requirement for, and response to, atmospheric oxygen (O2). Whereas essentially all eukaryotic organisms require oxygen to thrive, many species of bacteria can grow under anaerobic conditions.
Do microbes need oxygen?
Microorganisms vary in their requirements for molecular oxygen. Obligate aerobes depend on aerobic respiration and use oxygen as a terminal electron acceptor. They cannot grow without oxygen. Obligate anaerobes cannot grow in the presence of oxygen.
How does oxygen affect bacterial growth?
How does Oxygen affect bacterial growth? Bacteria can differ dramatically in their ability to utilize oxygen (O2). Under aerobic conditions, oxygen acts as the final electron acceptor for the electron transport chain located in the plasma membrane of prokaryotes.
Is Bacillus subtilis anaerobic?
The Gram-positive soil bacterium Bacillus subtilis, generally regarded as an aerobe, grows under strict anaerobic conditions using nitrate as an electron acceptor and should be designated as a facultative anaerobe.
Is Bacillus cereus positive for oxidase?
It was positive for urease, catalase, oxidase, deoxidization of nitrate, and Voges−Proskauer reaction. However, it was negative for methyl red, indole, H2S production, and phenylalanine deaminase reaction tests.
What are the characteristics of Bacillus cereus?
Bacillus cereus is a facultatively anaerobic, toxin-producing gram-positive bacterium found in soil, vegetation, and food. It commonly causes intestinal illnesses with nausea, vomiting, and diarrhea.
Overview
Bacillus cereus is a Gram-positive, rod-shaped, facultatively anaerobic, motile, beta-hemolytic, spore-forming bacterium commonly found in soil, food and marine sponges. The specific name, cereus, meaning "waxy" in Latin, refers to the appearance of colonies grown on blood agar. Some strains are harmful to humans and cause foodborne illness, while other strains can be beneficial as pr…
Ecology
Like most Bacilli, the most common ecosystem of Bacillus cereus is land. In concert with Arbuscular mycorrhiza (and Rhizobium leguminosarum in clover), they can regenerate heavy metal soil by increasing phosphorus, nitrogen, and potassium content in certain plants.
B. cereus competes with other microorganisms such as Salmonella and Campylobacter in the gut; its presence reduces the numbers of those microorganisms. In food animals such as chickens, r…
Pathogenesis
B. cereus is responsible for a minority of foodborne illnesses (2–5%), causing severe nausea, vomiting, and diarrhea. Bacillus foodborne illnesses occur due to survival of the bacterial endospores when infected food is not, or is inadequately, cooked. Cooking temperatures less than or equal to 100 °C (212 °F) allow some B. cereus spores to survive. This problem is compounded when food is then improperly refrigerated, allowing the endospores to germinate. Cooked foods …
Spore elimination
While B. cereus vegetative cells are killed during normal cooking, spores are more resistant. Viable spores in food can become vegetative cells in the intestines and produce a range of diarrheal enterotoxins, so elimination of spores is desirable. In wet heat (poaching, simmering, boiling, braising, stewing, pot roasting, steaming), spores require more than 5 minutes at 121 °C (250 °F) at the coldest spot to be destroyed. In dry heat (grilling, broiling, baking, roasting, searin…
Diagnosis
In case of foodborne illness, the diagnosis of B. cereus can be confirmed by the isolation of more than 100,000 B. cereus organisms per gram from epidemiologically-implicated food, but such testing is often not done because the illness is relatively harmless and usually self-limiting.
For the isolation and enumeration of B. cereus, there are two standardized methods by International Organization for Standardization (ISO): ISO 7932 and ISO 21871. Because of B. cere…
Prognosis
Most emetic patients recover within 6 to 24 hours, but in some cases, the toxin can be fatal via fulminant hepatic failure. In 2014, 23 newborns in the UK receiving total parenteral nutrition contaminated with B. cereus developed septicaemia, with three of the infants later dying as a result of infection.
Bacteriophage
Bacteria of the B. cereus group are infected by bacteriophages belonging to the family Tectiviridae. This family includes tailless phages that have a lipid membrane or vesicle beneath the icosahedral protein shell and that are formed of approximately equal amounts of virus-encoded proteins and lipids derived from the host cell's plasma membrane. Upon infection, the lipid membrane becomes a tail-like structure used in genome delivery. The genome is composed of about 15-kilobase, line…
History
Colonies of B. cereus were originally isolated from an agar plate left exposed to the air in a cow shed. In the 2010s, examination of warning letters issued by the US Food and Drug Administration issued to pharmaceutical manufacturing facilities addressing facility microbial contamination revealed that the most common contaminant was B. cereus.
Several new enzymes have been discovered in B. cereus, such as AlkC and AlkD, both of which a…