Online Microbiology and Biology Notes
Habitat of Bacillus cereus Bacillus cereus is isolated from soil, vegetables, milk, cereals, spices, fried rice, cooked poultry and meats, soups and desserts. It is also found in mashed potato, beef stew, apples, hot chocolates sold in vending machines and other improper food handling areas. In 1887, B. cereus was isolated from air in a cowshed by Frankland and Frankland. It …
Cultural Characteristics of Bacillus cereus Some of the characteristics are: Most Bacillus spp grow readily on nutrient agar or peptone media. The optimum temperature for growth varies from 20°C to 40°C, mostly 37°C. B. cereus is mesophilic and is capable of adapting to a wide range of environmental conditions. On Nutrient Agar at 37°C, it forms large (2-5 mm) grey-white, …
Morphology of Bacillus cereus Some of the characteristics are: Bacillus cereus is gram-positive rod-shaped bacilli with square ends. Occasionally may appear gram variable or even gram-negative with age. They are single rod-shaped or appear in short chains. Clear cut junctions between the members of chains are easily visible. Tissue section staining may appear long and filamentous. They are straight or …
Protocol: Isolation of Bacillus thuringiensis (Bt) from Soil sample Bacillus thuringiensis (Bt) is an ubiquitous, Gram-positive and sporulating bacterium that synthesizes insecticidal proteins with specificity against a wide range of insects during sporulation (Cry and Cyt) and vegetative growth (Vip and Sip). These proteins have portrayed Bt as an environment-friendly alternative to chemical insecticides. Principle of Isolation of Bacillus thuringiensis Widely used …
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Differences between Anthrax bacilli and Anthracoid bacilli The saprophytic organisms which simulate the anthrax bacillus closely, both in their morphological and cultural characters within the group of Gram-positive aerobic sporing bacilli are termed as Anthracoid bacilli. They have a general resemblance to anthrax bacilli such as producing dry wrinkled colonies and in the smear, appearing as chains of spore-bearing gram-positive …
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Biochemical Test of Bacillus anthracis Basic Characteristics Properties (Bacillus anthracis) Capsule Capsulated Catalase Positive (+ve) Gas Negative (-ve) Gelatin Hydrolysis Positive (+ve) Gram Staining Positive (+ve) Hemolysis Negative (-ve) Indole Positive (+ve) Motility Negative (-ve) Nitrate Reduction Positive (+ve) Oxidase Negative (-ve) Pigment Negative (-ve) Shape Rods Spore Positive (+ve) Urease Negative (-ve) VP (Voges Proskauer) Positive (+ve) Fermentation of …
Biochemical Test of Bacillus cereus Basic Characteristics Properties (Bacillus cereus) Catalase Positive (+ve) Citrate Positive (+ve) Gelatin Hydrolysis Negative (-ve) Gram Staining Positive (+ve) Growth in KCN Positive (+ve) Hemolysis Positive (+ve) Indole Negative (-ve) Motility Positive (+ve) MR (Methyl Red) Negative (-ve) Nitrate Reduction Variable Oxidase Negative (-ve) Pigment Negative (-ve) Shape Rods Spore Positive (+ve) VP (Voges Proskauer) …
Biochemical Test of Bacillus subtilis Basic Characteristics Properties (Bacillus subtilis) Catalase Positive (+ve) Citrate Positive (+ve) Flagella Flagellated Gas Negative (-ve) Gelatin Hydrolysis Positive (+ve) Gram Staining Gram Positive (+ve) Indole Negative (-ve) Motility Positive (+ve) MR (Methyl Red) Negative (-ve) Nitrate Reduction Positive (+ve) Oxidase Variable Pigment Negative (-ve) Shape Rods Spore Positive (+ve) Urease Negative (-ve) VP (Voges …
Laboratory Diagnosis of Bacillus cereus SPECIMENS: Faeces, vomitus, remaning food (if any), eye specimen (corneal swab) DIRECT DETECTION METHODS Microscopically the organisms appear as large gram positive rods in singles, pairs, or serpentine with square ends after Gram staining. Endospores formation are seen as unstained oval or round region within centre of cell. Spores are oval (ellipsoidal) and not swelling the …
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Clinical manifestation of Bacillus cereus A. Food poisoning Two forms of food poisoning: vomiting disease (emetic form) and diarrheal disease (diarrheal form). Emetic form The emetic form of disease results from the consumption of contaminated rice. Most bacteria are killed during the initial cooking of the rice, but the heat-resistant spores survive. If the cooked rice is not refrigerated, the …
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