what is the purpose of heat fixation for the bacterial smear?
Answer:
You flame the loop before to destroy any organisms already on it to prevent contamination of your culture. You flame it afterward to prevent unintended spread of bacteria, especially if the bacteria you are culturing is highly virulent (such as O157 E. coli). Heat fixation allows the bacteria to stick to the slide, instead of rinsing off with the various rinses used during the staining process. I hope this helps!
Heat fixation is the procedure used to adhere a bacterial smear to a glass slide for viewing by a compound microscope. It denatures the protiens on the surface of the bacteria causing them to be sticky.
After a smear has been allowed to dry at room temperature, the slide is gipped by tongs or a clothespin and passed through the flame of a Bunsen burner several times to heat-kill and adhere the organism to the slide. Heat fixation cannot be used in the capsular stain method as heat fixation will shrink or destroy the capsule (glycocalyx) and cannot be seen in stains.
Sterlizing of the inoculation loop is essential in order to avoid contamination of the slide preparations and also to prevent contamination of the inoculum plate.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment