Aseptic techniques for bacteria culture

Aseptic techniques for bacteria culture

Aseptic techniques and media used for bacteria culture

Using sterile techniques

* Bacteria are everywhere
* Media used for bacteria growth - welcoming for many bacteria
* We only want specific ones to grow
* Sterile remain sterile as long as doesn’t touch anything that isn’t sterile
* Also avoid prolonged exposure to air

Sterile techniques: what can you do in the lab?
* Wash your hands
* Keep your bench clean
* Wear gloves
* Flame loop, neck of tube
* Keep cap facing down
* Work quickly albeit efficiently
* Limit talking when opening cultures

Autoclaving

* Apparatus used to sterilize liquid and instrument
* Heating up to 121oC at 15 psi for 15 minutes
* Kill most microbe
* Autoclave tape - chemical reaction - black stripes if autoclaving ok

Culture media
Bacteria colonies
Composition of media

* NA = Nutrient Agar
o peptone, beef extract, salt, agar 1.5%
* TSA = Tryptic soy agar
o Peptone from casein, peptone from soymeal, sodium chloride, agar 1.5%
* Many other medias available. These 2 will be used very often in this lab
* Note: Peptone: enzymatic digest protein

Few notes on agar

* Not degraded by most bacteria
* Is liquified at 100oC and remain liquid until about 40oC
* If added to growth medium - medium becomes solid
* Semi solid media: 0.5% agar
* Broth: no agar
* Solid media: 1.5-3% agar

How to prepare a Petri plate

* Take liquid agar (in the water bath)
* Pour aseptically into the base of the Petri plate (top is larger than the base)
* Wait until solidify (15 minutes) - invert
* ***Plates are kept inverted so condensation does not drip onto the agar

Pouring a plate
Objective : Cultivate bacteria sample from the environment
How to inoculate a plate
Colonial morphology
Description
How to open a tube
How to inoculate a deep
Bacteria motility
Oxygen requirement
Deep observation
How to inoculate a slant
Slant observation
How to inoculate a broth
Broth observation
Uses
Synthesis

* Cultivate a bacterial sample from the environment. Incubate 27o C
* Inoculate the pure culture provided
o Into a broth
o Into a slant
o Into a deep
o Into a Petri plate
o *** Using aseptic techniques ***Put all the above in the 37oC incubator
* Describe colonial morphology from a Petri plate and a slant
* Identify growth pattern in broth and deep


Aseptic techniques for bacteria culture.ppt