What is lecithinase activity?
Lecithinase is a type of phospholipase that acts upon lecithin. It can be produced by Clostridium perfringens, Staphylococcus aureus, Pseudomonas aeruginosa or Listeria monocytogenes. aureus is used in detection of coagulase-positive strains, because of high link between lecithinase activity and coagulase activity.
Does E coli produce lecithinase?
The lecithinase gene of the intracellular pathogen Listeria monocytogenes, plcB, was identified in a 5,648-bp DNA fragment which expressed lecithinase activity when cloned into Escherichia coli. This fragment is located immediately downstream of the previously identified gene mpl (prtA).
How do you test for lecithinase?
Procedure
- Take a loopful of test organism and streak it as a straight line on the plate.
- Incubate anaerobically in a gas pak jar immediately after streaking and transfer into the incubator maintained at 35-37oC for 24-48 hours for anaerobes and for aerobes incubate the plate at 35-37oC for 24-48 hours.
What is the principle of methyl red test?
In the methyl red test (MR test), the test bacteria is grown in a broth medium containing glucose. If the bacteria has the ability to utilise glucose with production of a stable acid, the colour of the methyl red changes from yellow to red, when added into the broth culture.
Is lecithinase a lipase?
Bacterial lecithinases break down this lecithin to an insoluble diglycerides resulting in an opaque halo, surrounding the colony when grown on the egg yolk agar medium. The Lipase enzyme hydrolyzes the fats within the egg yolk, which results in an iridescent sheen on the colony surface.
Why coagulase test is done?
The coagulase test identifies whether an organism produces the exoenzyme coagulase, which causes the fibrin of blood plasma to clot. The coagulase slide test is used to identify the presence of bound coagulase or clumping factor, which is attached to the cell walls of the bacteria.
Why is methyl red test done?
The methyl red test is used to detect the ability of an organism to produce and maintain acid end products from glucose fermentation.
What is the principle of the lecithinase test?
Principle of Lecithinase Test Lecithinases or phospholipases are enzymes released by bacteria that have the ability to destroy animal tissues and play a role in pathogenecity. Lecithinase, which is also called phospholipase C, is such an enzyme that splits the phospholipid lecithin.
When to use egg yolk agar plate for lecithinase test?
If Clostridia species is suspected in a clinical sample, an egg yolk agar plate can be used to check for the production of Lecithinase and Lipase activity of the suspected sample.
What kind of Bacillus is Lecithinase Positive?
Among Bacillus species, B. thuringiensis and B.anthracis are lecithinase positive or weakly positive. B. anthracis, however, is a nonmotile organism and produces nonhemolytic colonies. Lecithin is a normal component of egg yolks.
How is lecithinase broken down in an egg yolk?
Bacterial lecithinase breaks down this lecithin into lecithinase into phosphorylcholine and an insoluble diglyceride, which forms a precipitate in the medium. This precipitate appears as a white opaque halo surrounding the lecithinase-producing colony grown on the egg yolk agar medium.