is bacillus cereus aerobic or anaerobic

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Is Bacillus cereus enteric or anaerobe?

Bacillus cereus is a facultative anaerobe and a spore-forming enteric pathogen. Bacillus cereus causes two distinct types of GI diseases: the emetic and diarrheal syndromes (Bottone, 2010). The emetic syndrome is caused by the emetic toxin cereulide found in food products and exhibits a short incubation period.

Is B cereus an aerobic spore bearer?

B. cereusmay be the most common aerobic spore bearer in many types of soil and in sediments, dust, and plants (107). B. cereusis also frequently present in food production environments due to the adhesive nature of its endospores (7). This characteristic enables the bacterium to spread to all kinds of food.

Is B cereus f4430 anaerobic or aerobic?

In this study, the aerobic vegetative growth and anaerobic vegetative growth of the food-borne pathogen B. cereus F4430/73 strain were compared with those of the genome-sequenced ATCC14579 strain using glucose and glycerol as fermentative and nonfermentative carbon sources, respectively.

What is the natural environment of Bacillus cereus?

The natural environmental reservoir for B. cereusconsists of decaying organic matter, fresh and marine waters, vegetables and fomites, and the intestinal tract of invertebrates (71), from which soil and food products may become contaminated, leading to the transient colonization of the human intestine (53).

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Is Bacillus cereus an anaerobe?

Summary: Bacillus cereus is a Gram-positive aerobic or facultatively anaerobic, motile, spore-forming, rod-shaped bacterium that is widely distributed environmentally.

Is Bacillus bacteria aerobic or anaerobic?

bacillus, (genus Bacillus), any of a genus of rod-shaped, gram-positive, aerobic or (under some conditions) anaerobic bacteria widely found in soil and water. The term bacillus has been applied in a general sense to all cylindrical or rodlike bacteria.

Does Bacillus cereus need oxygen?

B. cereus growth is optimal in the presence of oxygen, but can occur under anaerobic conditions.

Are Bacillus bacteria anaerobic?

Bacillus species are rod-shaped, endospore-forming aerobic or facultatively anaerobic, Gram-positive bacteria; in some species cultures may turn Gram-negative with age.

Are Bacillus obligate aerobes?

Bacillus species can be either obligate aerobes which are dependent on oxygen, or facultative anaerobes which can survive in the absence of oxygen. Cultured Bacillus species test positive for the enzyme catalase if oxygen has been used or is present.

Is Bacillus subtilis aerobic?

Even though B. subtilis is still generally considered to be an obligate aerobe, several recent studies have proved that this bacterium is in fact a facultative anaerobe, which is capable of both fermentation and anaerobic respiration with either nitrate or nitrite used as the terminal electron acceptor (19, 20).

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).

Is Bacillus cereus a lactose fermenter?

cereus isolates are unable to ferment lactose, they can grow in milk products upon hydrolysis of milk proteins or by glucose consumption following the fermentation of lactose by competitive microorganisms, for example lactic acid bacteria.

What type of metabolism does Bacillus cereus have?

facultative aerobe4.3 Metabolism B. cereus is a facultative aerobe so it can utilize oxygen as a terminal electron accepter, but also has methods of anaerobic respiration as a mechanism of energy release.

Is Bacillus aerobic or anaerobic nitrogen fixer?

therefore it is an anaerobic nitrogen fixation.

Is Bacillus subtilis aerobic or facultative anaerobe?

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.

What are anaerobic bacteria?

Anaerobic bacteria are germs that can survive and grow where there is no oxygen. For example, it can thrive in human tissue that is injured and does not have oxygen-rich blood flowing to it. Infections like tetanus and gangrene are caused by anaerobic bacteria.

Where is Bacillus cereus found?

Bacillus cereus is ubiquitous in nature and is found on soil, on plants, and in the enteric tract of insects and mammals. From these niches it is easily spread to food products, causing an emetic or diarrheal syndrome. The former is due to cereulide, a small toxin whose genetic determinants are plasmid borne.

Why is Bacillus cereus important?

Importance to the Food Industry. Bacillus cereus spores are able to survive low-temperature processing, which occurs, for example, in spray drying. Therefore, any food product that is a spray-dried powder is subject to contamination by B. cereus.

What is B. cereus resistant to?

B. cereus endospores are resistant to heat, radiation, disinfectants, and desiccation, and their adhesive characters facilitate their attachment to processing equipment and resistance to cleaning procedures. These organisms frequently contaminate clinical environments, biotechnological processes, and food production. B. cereus is known to be a causative organism for a wide range of opportunistic infections, both in immunocompromised and in immunocompetent patients, causing two distinct foodborne illness syndromes, namely diarrhea and emesis, and a wide range of opportunistic infections such as severe endophthalmitis, bacteremia, septicemia, endocarditis, pneumonia, meningitis, gastritis, and cutaneous infections. B. cereus infection can produce enterotoxins in the human small intestine, causing diarrheal food poisoning. B. cereus intoxication leads to the production of a toxin, cereulide, causing emesis.

Why is B. cereus a problem?

The organism causes spoilage, which has been termed ‘broken cream’ or sweet curdling of milk. This is because of its proteolytic activity in the absence of high levels of acid production. View chapter Purchase book.

What temperature does B. cereus grow?

B. cereus can grow over a wide temperature range (8–55 °C), but it is not well suited to tolerate low pH values (minimum 5–6) or water content (minimum water activity 0.95).

Which bacteria are responsible for foodborne diseases?

Bacillus species outside the B. cereus group have been implicated in foodborne disease. Species such as Bacillus subtilis, Bacillus mojavensis, Bacillus pumilus, and Bacillus licheniformis can produce cyclic lipopeptides which show toxic activity, although their link to foodborne disease remains uncertain.

Which bacteria forms the polypeptide amphomycin?

Bacillus cereus forms the polypeptide amphomycin which, at a slightly higher concentration (25 μg/ml), inhibits the transfer of mannose to phosphodolichol as well as to oligosaccharyl diphosphodolichol and glycoprotein in membrane preparations of aorta [221].

What are the spores of Bacillus cereus?

Bacillus cereus is a ubiquitous microorganism. The spores are present in soil from 10 2 cfu g −1 and up to more than 10 5 cfu g −1. Consequently, food products of plant origin frequently contain B. cereus spores. Soil is an important source of contamination for milk. There is a marked seasonal variation in the spore content of raw milk, with higher levels during the pasture period, when the teats of the cow may be contaminated with soil. Dirty teats that are not cleansed before milking are an important contamination source, particularly during wet weather. Bacillus cereus is able to grow and sporulate on insufficiently cleaned milking equipment, so equipment may be a secondary source of contamination. Used bedding material and feed may also contain spores of B. cereus.

Where is Bacillus cereus found?

Introduction. Bacillus cereus is ubiquitous in the environment and can be found in soil, dust, air, water, decaying matter and plants. From there, it moves into the food chain, and so raw foods of plant origin are the major source of B. cereus.

What is the gram positive bacteria that causes diarrhea?

Bacillus cereus is a gram-positive, rod-shaped, spore-forming bacterium that has the ability to grow at a variety of temperatures and pH. Two types of illnesses arise as a result of consumption of food contaminated with B. cereus, emetic and diarrheal. The emetic syndrome is usually associated with starchy foods such as fried rice, pasta, etc. The illness is caused due to the ingestion of a pre-formed toxin in food (i.e., intoxication). The diarrheal syndrome, on the other hand, is associated with other types of foods such as milk, salads, and meat. Unlike the emetic syndrome, the diarrheal illness is caused by ingesting a large number of bacterial cells (i.e., toxico-infection). Healthy individuals usually recover from B. cereus illness within a day or two but patients who have other health issues might suffer serious complications. To control this bacterium in food, proper cooking and rapid cooling are required to prevent spores from germinating.

What is Bacillus cereus food poisoning?

Bacillus cereus food poisoning is the general description of illness associated with this organism, although two recognized types of illness are caused by two distinct metabolites (toxins). The diarrheal type of illness is caused by a large-molecular-weight protein and the vomiting (emetic) type of illness is associated with cereulide, ...

What is the gram positive bacterium?

Bacillus cereus. Tarek F. El-Arabi, Mansel W. Griffiths, in Foodborne Infections and Intoxications (Fourth Edition), 2013. Bacillus cereus is a gram-positive, rod-shaped, spore-forming bacterium that has the ability to grow at a variety of temperatures and pH.

Which bacteria forms the polypeptide amphomycin?

Bacillus cereus forms the polypeptide amphomycin which, at a slightly higher concentration (25 μg/ml), inhibits the transfer of mannose to phosphodolichol as well as to oligosaccharyl diphosphodolichol and glycoprotein in membrane preparations of aorta [221].

Which organisms are closely related to B. cereus?

cereus group of organisms, which contains species that are very highly related at the 16S rDNA level: B. cereus, Bacillus mycoides, Bacillus pseudomycoides, Bacillus thuringiensis, Bacillus weihenstephanensis, Bacillus cytotoxicus, Bacillus toyonensis, and Bacillus anthracis.

Which cells do Bacillus cereus spores adhere to?

Bacillus cereusspores, which are hydrophobic and have projecting appendages, adhere to Caco-2 and small-intestine epithelial cells (5) and HeLa cells (110). In these studies, spores adhered in aggregates, which, when germinating, released high concentrations of tissue-destructive toxins.

What is the morphology of B. cereus?

anthracisdisplay a range of morphological forms depending upon the milieu in which they are observed. In Gram-stained smears of body fluids such as anterior-chamber aspirates or broth cultures, B. cereuspresents as straight or slightly curved slender bacilli with square ends singly or in short chains (Fig. ​(Fig.1).1). Clear-cut junctions separating members of the chain are distinctly displayed. Gram-stained smears prepared from agar growth will show more uniform bacillary morphology with oval, centrally situated spores, which do not distort the bacillary form. In tissue sections such as those shown in Fig. ​Fig.2,2, long, slender, bacillary forms may predominate, with some clearly displaying polyhydroxybutyrate vacuoles, which may be confused with spores. Long filamentous forms characterized as filamentation may also show beading, which may preclude identification as a Bacillusspecies (Fig. ​(Fig.3).3). In wet preparations of body fluids or broth cultures, the peritrichous bacilli are motile, displaying a leisurely gait rather than darting motility.

How does B. cereus colonize the oral cavity?

cereuseither through the inhalation of spores or by vegetative bacteria passing through in B. cereus-contaminated food (31, 44). Foci can be established by the entrapment of bacteria in furrows in the oral cavity in which the bacterium may develop locally and elaborate toxins, which can spread to adjacent tissues, or the bacterium can disseminate to other body sites. A report by Strauss et al. (124) of the development of pseudomembranous tracheobronchitis in a 52-year-old female patient with aplastic anemia suggests that treatment-mediated damage to the buccal mucosa may expedite spore/vegetative cell adherence and colonization. Fiber-optic bronchoscopy of the patient revealed a severely inflamed tracheal and bronchial mucosa accompanied by white diphtheria-like membranes obstructing the lower lobe bronchi on the left side. Over an 8-h period, the membranes spread and obstructed the entire visible bronchial system. B. cereuswas recovered from blood and bronchoalveolar lavage cultures and the membrane biopsy specimen. As this patient's initial symptoms included chest pain, yellowish sputum, and a rapid progression of the infection, the authors likened her infection to pulmonary anthrax. B. cereuscolonization of the oral cavity, as noted here and elsewhere (31, 44), may well be an underappreciated first stage in the pathogenesis of pulmonary as well as systemic infections in immunocompromised individuals.

What are the toxins in B. cereus?

Among these secreted toxins are four hemolysins (56), three distinct phospholipases, an emesis-inducing toxin, and three pore-forming enterotoxins: hemolysin BL (HBL), nonhemolytic enterotoxin (NHE), and cytotoxin K (91, 92, 114). In the gastrointestinal tract (small intestine), vegetative cells, ingested as viable cells or spores, produce and secrete a protein enterotoxin and induce a diarrheal syndrome, whereas emetic toxin, a plasmid-encoded cyclic peptide (cereulide), is produced in food products and ingested preformed. In rabbit ligated ileal-loop assays, culture filtrates of enterotoxigenic strains induce fluid accumulation and hemolytic, cytotoxic, dermonecrotic, and vascular permeability activities in rabbit skin (13).

What is the most common aerobic spore bearer in soil?

B. cereusmay be the most common aerobic spore bearer in many types of soil and in sediments, dust, and plants (107). B. cereusis also frequently present in food production environments due to the adhesive nature of its endospores (7). This characteristic enables the bacterium to spread to all kinds of food.

What is the reservoir of B. cereus?

The natural environmental reservoir for B. cereusconsists of decaying organic matter, fresh and marine waters, vegetables and fomites, and the intestinal tract of invertebrates (71), from which soil and food products may become contaminated, leading to the transient colonization of the human intestine (53). Spores germinate when they come into contact with organic matter or within an insect or animal host (7). A multicellular filamentous growth pattern containing refractile inclusions, termed arthromitus (rooted), has been observed in the guts of certain arthropods, which is regarded as the normal intestinal stage in soil-dwelling insects (95). In this setting, as long rod-shaped bacteria, the bacilli lose their flagella, attach to the arthropod intestinal epithelium, and sporulate (95). B. cereusalso has a saprophytic life cycle in which spores germinate in soil, with the production of a vegetative bacillus, which could then sporulate, maintaining the life cycle (7). Defecation by or death of the host releases cells and spores into the soil, where vegetative cells may sporulate and survive until their uptake by another host (71, 135). Furthermore, when B. cereusgrows in soil, it undergoes a switching from a single-cell to a multicellular phenotype, which allows it to translocate through the soil (135). This morphogenic phase is analogous to B. cereusswarming on agar media (118).

Why is it important to have a B. cereusisolate for a reference center?

Because most Bacillusspecies (except B. anthracis) isolated from blood cultures and even from open wounds are often regarded as contaminants, it becomes critical for the clinical microbiology laboratory to alert infection control practitioners if a sudden increase in the isolation of this bacterial species is noted. If such a scenario arises, B. cereusisolates should be forwarded to a reference center for serotyping and/or subjected to genotypic fingerprinting (86) to determine if isolates are clonal, which could lead to a point source of contamination.

What is the micrograph of Bacillus cereus?

Electron micrograph of Bacillus cereus. Bacillus cereus is a Gram-positive, rod-shaped, facultatively anaerobic, motile, beta-hemolytic, spore forming bacterium commonly found in soil and food. The specific name, cereus, meaning "waxy" in Latin, refers to the appearance of colonies grown on blood agar.

What is the pathogen of B. cereus?

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 inadequately, cooked.

What is the bacteria that is contracted from rice?

The bacteria is classically contracted from fried rice dishes that have been sitting at room temperature for hours. B. cereus bacteria are facultative anaerobes, and like other members of the genus Bacillus, can produce protective endospores. Its virulence factor s include cereolysin and phospholipase C. The Bacillus cereus group comprises seven ...

How many B. cereus organisms are there in food?

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.

How long does it take for B. cereus to double?

At 30 °C (86 °F), a population of B. cereus can double in as little as 20 minutes or as long as 3 hours, de pending on the food product. Food. Minutes to double, 30 °C (86 °F) Hours to multiply by 1,000,000. Milk.

What is the ISO 7931 method for enumeration of B. cereus?

Because of B. cereus ' ability to produce lecithinase and its inability to ferment mannitol, there are some proper selective media for its isolation and identification such as mannitol-egg yolk-polymyxin (MYP) and polymyxin-pyruvate-egg yolk-mannitol-bromothymol blue agar (PEMBA). B. cereus colonies on MYP have a violet-red background and are surrounded by a zone of egg-yolk precipitate.

How long does it take for enterotoxin to be inactivated?

Enterotoxin can be inactivated after heating at 56 °C (133 °F) for 5 minutes, but whether its presence in food causes the symptom is unclear, since it degrades in stomach enzymes; its subsequent production by surviving B. cereus spores within the small intestine may be the cause of illness.

What is the name of the chromogenic agar used to detect Bacillus cereus?

January 2012: The Bacillus Chapter has been updated with the inclusion of a new optional chromogenic agar, Bacara agar, for the detection and enumeration of Bacillus cereus in foods. Bacillus cereus is an aerobic spore-forming bacterium that is commonly found in soil, on vegetables, and in many raw and processed foods.

How to calculate B. cereus cells/g?

Calculate number of B. cereus cells/g of sample, based on percentage of colonies that are morphologically consistent with B. cereus. For example, if average count obtained with 10 -4 dilution of sample was 65 and 4 of 5 colonies tested were confirmed as B. cereus, the number of B. cereus cells/g of food is 65 × 4/5 × 10,000 × 10 = 5,200,000. ( NOTE: Dilution factor is tenfold higher than sample dilution because only 0.1 mL was tested).

What isolates produce large Gram positive rods with spores that do not swell the sporang?

Record results obtained with the different confirmatory tests. Tentatively identify as B. cereus those isolates which 1) produce large Gram-positive rods with spores that do not swell the sporangium; 2) produce lecithinase and do not ferment mannitol on MYP agar; 3) grow and produce acid from glucose anaerobically; 4) reduce nitrate to nitrite (a few strains may be negative); 5) produce acetylmethylcarbinol (VP-positive); 6) decompose L-tyrosine; and 7) grow in the presence of 0.001% lysozyme.

How to incubate phenol red glucose broth?

Phenol red glucose broth . Inoculate 3 mL broth with 2 mm loopful of culture. Incubate tubes anaerobically 24 h at 35°C in GasPak anaerobic jar. Shake tubes vigorously and observe for growth as indicated by increased turbidity and color change from red to yellow, which indicates that acid has been produced anaerobically from glucose. A partial color change from red to orange/yellow may occur, even in uninoculated control tubes, due to a pH reduction upon exposure of media to CO 2 formed in GasPak anaerobic jars.

How long to incubate tyrosine agar?

Incubate slants 48 h at 35°C. Observe for clearing of medium near growth, which indicates that tyrosine has been decomposed. Examine negative slants for obvious signs of growth, and incubate for a total of 7 days before considering as negative.

How to count B. cereus?

Mark bottom of plates into zones with black felt pen to facilitate counting and count colonies that are typical of B. cereus. This is the presumptive plate count of B. cereus. Pick at least 5 presumptive positive colonies from the Bacara or MYP plates and transfer one colony to BHI with 0.1% glucose for enterotoxin studies (Chapter 15) and a nutrient agar slant for storage. Typical colonies grown on Bacara or MYP must be confirmed with biochemical testing as described in Sections F and H below.

What foods are contaminated with B. cereus?

Foods incriminated in past outbreaks include cooked meat and vegetables, boiled or fried rice, vanilla sauce, custards, soups, and raw vegetable sprouts. Two types of illness have been attributed to the consumption of foods contaminated with B. cereus.

What are the toxins in B. cereus?

Among these secreted toxins are four hemolysins, three distinct phospholipases, an emesis-inducing toxin, and proteases.

Is Bacillus cereus Gram positive?

Bacillus cereus is a Gram-positive aerobic or facultatively anaerobic, motile, spore-forming, rod-shaped bacterium that is widely distributed environmentally. While B. cereus is associated mainly with food poisoning, it is being increasingly reported to be a cause of serious and potentially fatal non-gastrointestinal-tract infections.

Is Bacillus cereus a pathogen?

Bacillus cereus, a volatile human pathogen. Bacillus cereus is a Gram-positive aerobic or facultatively anaerobic, motile, spore-forming, rod-shaped bacterium that is widely distributed environmentally. While B. cereus is associated mainly with food poisoning, it is being increasingly reported to be a cause of serious and potentially fatal no ….

Is Bacillus cereus an aerobic organism?

Bacillus cereus is a Gram-positive aerobic or facultatively anaerobic, motile, spore-forming, rod-shaped bacterium that is widely distributed environmentally. While B. cereus is associated mainly with food poisoning, it is being increasingly reported to be a cause of serious and potentially fatal no ….

What are the factors that differentiate Bacillus cereus from other Bacillus spp.?

The following factors are used to differentiate B. cereus from other Bacillus spp.: Presence of crystal toxins. B. thuringiensis produces crystal toxins which are used as pesticides and in some cases may allow an enterotoxic strain to enter the human body, causing a food-borne illness. Haemolytic activity.

Where is B. cereus found?

The infective dose can vary depending on the amount of enterotoxin produced. B. cereus is widespread in the environment and can be isolated from soil and vegetation. It is found in a variety of foods which include rice and other starches; prepared foods such as soups, sauces and puddings; milk, meat and vegetables.

What is the difference between B. mycoides and B. pseudomycoides?

mycoides and B. pseudomycoides have characteristic rhizoid colonies with their root-like structure and creamy appearance. They can be differentiated by differences in fatty acid composition and DNA-DNA relatedness.

What is the name of the bacterium that produces toxins?

Fact Sheet on Bacillus cereus. By Naomi Osborne 10.07.2013. Description. Bacillus cereus is a Gram-positive, rod-shaped, facultative anaerobic bacterium that can produce toxins which cause food poisoning. It belongs to the Bacillus genus and shares similar characteristics, such as forming protective endospores, ...

How long does it take for B. cereus to incubate?

The incubation period is 30 minutes to 6 hours and illness usually lasts around 24 hours. Diarrhoeal: The diarrhoeal form can be caused by consumption of food such as meat and ready prepared meals which have been improperly stored. B. cereus thrives at room temperature and following consumption, produces a toxin in the intestine ...

How many cases of B. cereus are there in the US?

The estimated number of B. cereus food poisoning cases in the US is 64,000 each year.

Is B. cereus a single species?

cereus has a similarity score of >97% with five other pathogenic Bacillus spp., suggesting that they should be classified as a single species. However, virulence factors and their ability to cause more than one type of food-borne illness argue against this. The following factors are used to differentiate B. cereus from other Bacillus spp.:

What is Bacillus cereus?

Bacillus cereus: Morphology, Disease, Biochemical Tests. Acharya Tankeshwar Bacteriology 0. Last updated on June 21st, 2021. There are two medically important Bacillus species: Bacillus anthracis which causes anthrax, and Bacillus cereus, which causes a foodborne illness (food poisoning) similar to that of Staphylococcus.

How many enterotoxins does Bacillus cereus produce?

Bacillus cereus produces two enterotoxins, emetic (vomiting) and diarrheal – causing two types of illness.

What is a chromogenic agar?

MYP agar or chromogenic agar named Bacara is used to isolate B. cereus from food sample. MYP agar is comparatively less selective (which may create problems for the recovery of the target organism but inhibits the growth of background flora) compared to Bacara, which is both selective and differential agar and some scientist/researchers have suggested using this chromogenic agar for the enumeration of B. cereus group as a substitute for MYP .

What color are B. cereus colonies?

Colonies of B. cereus on MYP and Bacara agar medium (Image source) After 18-24 hr incubation at 30°C B. cereus colonies are usually a pink-orange color on Bacara or pink on MYP and may become more intense after additional incubation.

What is a Gram positive rod?

Gram-positive rods often arranged in pairs or chains with rounded or square ends and usually have a single endospore. Endospore is generally oval or sometimes round or cylindrical and is very resistant to adverse conditions.

How long does a clostridial gastroenteritis last?

The incubation period is long; 12-18 hours and the illness usually lasts for 1-2 days, although it can continue for several days. Symptoms are usually mild with abdominal cramps, watery diarrhea, and nausea resembling clostridial gastroenteritis.

Is Bacillus oxidase positive?

Most species are oxidase- positive, which may lead to confusion with Pseudomonas species, especially if the Bacillus species are poorly stained.

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