Sterile techniques - (Mar/22/2005 )
It says; " wrap everything you put into the hood with 70% EtOH". Does it mean that sterile tubes and flasks also have to be wrapped before i put them into the hood?
How can I sterilize the components of the media? Should both liquid and solid components be sterilized? Should i sterilize them everytime before i use them? And do i have to sterilize them if they are newly bought/ never opened before? 
Thanks.
It says; " wrap everything you put into the hood with 70% EtOH". Does it mean that sterile tubes and flasks also have to be wrapped before i put them into the hood?
Yes, everything entering the hood should be sprayed with EtOH 70% (included your hands!)
How can I sterilize the components of the media? Should both liquid and solid components be sterilized? Should i sterilize them everytime before i use them? And do i have to sterilize them if they are newly bought/ never opened before?
There is a very nice chapter in the book "Culture of animal cells - a manual of basic techniques" by R.I.Freshney which talks about how to sterilize wich components. Some can be autoclaved, others have to be filtered etc. You generally sterilize once when you start using the component (unless it is mentionned that it was sterilized, like on most of the media you'll buy.[COLOR=blue]
Try to get this book, it is quite helpful!
Sabrina
Hi,
I just drench everything in ethanol before it goes into the hood, hands and all (gloves of course).
Even if materials come in sterile packaging, as soon as you open that packaging outside the hood, they become non-sterile and must be sprayed down. If you open the packaging inside the hood then they do not - but the outside of the packaging must be sprayed down before hand.
Reagents for media preparation should be supplied in a sterile container (which it will say on the label) and i think its best to vacuum filter your media once its been prepared.
Hope this helps
Jon
hi
i agree with mnqcljsm and sabrinarosa.
the majority of culture products may not be autoclaved. Therefore all medias, plates... sealed are sterile. Hence i wash with detergent the vials and gloves that have been opened or transported out of the hood
i never get contamination.
caution : if you use latex gloves, ethanol partially permeabilises the latex.
i agree with mnqcljsm and sabrinarosa.
the majority of culture products may not be autoclaved. Therefore all medias, plates... sealed are sterile. Hence i wash with detergent the vials and gloves that have been opened or transported out of the hood
i never get contamination.
caution : if you use latex gloves, ethanol partially permeabilises the latex.
The other thing to remember about ethanol is that it is NOT A STERILANT! It is completely possible for bacterial spores to survive in your ethanol, especially if you mix your own and/or refill your own spray bottles.
When I mixed my own 70% ethanol, I sterile filtered it into sterile bottles, and then handled them like I handled sterile media - open only in the hood, and handle aseptically.
Katherine
In fact ethanol isn't as good as isopropanol for sterilizing anyway ... I suggest you use this or something along these lines as they are sterile and double bagged, can be kept in the hood (worth the extra $$ believe me):
http://www.vwrsp.com/catalog/product/index...172&resultNum=0