Lab One Flashcards
How is tryptic soy broth prepared?
70ml of distilled water is added to 4.2ml of TSB powder and mixed to dissolve and then another 70ml of distilled water is added
What colour is tryptic soy broth?
light brown
what is the feature of a none sterile liquid?
it is turbid (cloudy)
what is a feature of a sterile liquid?
it is not turbid (clear)
what was the only sterile broth in the sterillity lab experiment?
The bottle with the lid that was autoclaved
what can cause a culture to be non sterile?
contamination from air, non-sterile container, non-sterile broth
how is Tryptic Soy Agar prepared?
Agar is added to Tryptic Soy Broth, and then autoclaved to dissolve the agar and sterilize it. This is done under aseptic technique.
what is the pH of tryptic soy agar?
7.3 +/- 0.2
what is the formula of tryptic soy agar?
Tryptone (panreatic digest of casein) 17.0g
Enzytmatic digest of soybean meal 3.0g
Sodium chloride 5.0g
Di-potassium hydrogen phosphate 2.5g
Glucose (dextrose) 2.5g
Distilled water 1000ml
what percentage of agar is added to the tryptic soy broth?
1.5%
why is aseptic technique used?
to prevent the microbial contamination of laboratory workers, contamination from the environment they are working in and contamination of the species they are working on
when is aseptic technique used?
whenever specimens are to be transferred between media
what is subculturing?
use of aseptic technique procedures to maintain a pure culture when transferring microorganisms from media containing culture to fresh media not containing culture
what is the first step in subculturing?
plate streaking is the first step in subculturing to ensure that the bacteria is pure, followed by microscopic examination
what are the four subculturing procedures?
solid to solid- plate culture to plate
Solid to liquid- plate cultre to broth
Liquid to solid- broth culture to plate
Liquid to liquid- broth culture to broth
what is the procedure of subculturing into a liquid media?
- agar plate, agar side up
- lid lightly loosened on the culture
- flame the loop tp sterilize and allow to cool
- remove the lid from the culture and flame the opening, do not put the lid down on the bench
- move the loop up and down on the side of the broth container
- flame the top of the bottle and replace the lid
- flame the loop
(loosen the lid slightly before incubation)
what do you do to the lid of a bottle before incubation?
loosen it slightly to account for the build-up in pressure when inside the autoclave
what is the procedure for subculturing onto a solid culture medium?
- place both plates agar side up
- flame the loop and allow to cool
- touch the loop to an isolated colony on the agar surface
- use the streak plate method
what is the streak plate method?
- streaking a portion of the agar plate with an inoculum
- further portions of the plate are streaked to dilute the inoculum to form single colony-forming units (CFUs), which give rise to isolated colonies
what are CFUs?
colony-forming units.
each colony-forming unit gives rise to an isolated colony
when are the times to flame the loop in the streak plate method?
before picking up the inoculum
after streak 1
after streak 3
what are proteus?
bacteria that are classified by being rapidly motile
what is the structure of a proteus?
has a flagella that is visible when starined with a flagella stain
how do protues move look on an agar plate?
when inoculated at the centre or agar, they swarm and form concentric rings
