What is the colony morphology of Bacillus cereus?

Published by Charlie Davidson on

What is the colony morphology of Bacillus cereus?

cereus colonies are large, feathery, dull, gray, granular, spreading colonies, and opaque with a rough matted surface and irregular perimeters. On blood agar, it is beta-hemolytic. Colony perimeters are irregular and represent the configuration of swarming from the site of initial inoculation, perhaps due to B.

How do you test for Bacillus cereus?

The traditional method of B. cereus detection is based on the bacterial culturing onto selective agars and cells enumeration. In addition, molecular and chemical methods are proposed for toxin gene profiling, toxin quantification and strain screening for defined virulence factors.

Is Bacillus cereus motile or nonmotile?

cereus those isolates which are actively motile and strongly hemolytic and do not produce rhizoid colonies or protein toxin crystals. Nonmotile B. cereus strains are also fairly common and a few strains are weakly hemolytic. These nonpathogenic strains of B.

How does Bacillus cereus spoil milk?

They can contaminate raw milk by simple transfer during milking, when hygiene conditions are not fully observed, and some strains of the species may cause mastitis in very rare cases. Pasteurization induces sporulation of B. B. cereus sensu stricto has been identified in virtually all categories of foods.

Is Bacillus cereus positive for catalase?

Bacillus cereus is an aerobic, Gram-positive, catalase-positive, bacillus, which may produce oval, central endospores. Vegetative cells occur singly or in short chains and the organism grows readily on nutrient agar and peptone media to yield granular or wrinkled colonies.

What is the treatment for Bacillus cereus?

B. cereus produces beta-lactamases, unlike Bacillus anthracis, and so is resistant to beta-lactam antibiotics; it is usually susceptible to treatment with clindamycin, vancomycin, gentamicin, chloramphenicol, and erythromycin. Simultaneous therapy via multiple routes may be required.

Is B. cereus positive for starch hydrolysis?

Most B. cereus isolates possessed the hemolysis gene, but not the ces gene. The infant formula isolates showed stronger hemolysis activity than the other isolates. Over 90% of the RTE food isolates and only 35% of the infant formula isolates were positive for starch hydrolysis.

Is B. cereus catalase positive or negative?

Physiology and Pathogenesis B. Cereus is motile, catalase positive, able to ferment glucose, unable to ferment lactose, able to reduce nitrate to non gaseous nitrogenous compounds, produces amylase, and has alpha hemolytic activity.

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