10 replies to this topic

[neuron]

This could be a very stupid but a basic question. Why do the buffers like tris go contaminated? as in why we see the growth or little fibres in buffers? what kind of contamination is that? And what is the good way to store the buffers that are used for pH calibration?

[Pangea]

Are the buffers bought from a company and is there SDS inside? One PhD in our Lab changed the whole Kit because she was not able to read. How stuipid, isnt? Generally, most buffer are store in RT. If there is contamination then it is quite a old solution. Try to for cell culture always aotuclaving the solution and the others in the Lab as you know wiht ddH2O and store tightly closed. Make new once if frequently used. To my knowledge like TAE or TBE or Running Buffer you can make stock solutions so there is no chance to growth for contaminants. And its not specific for TRIS its just a matter of handling your solution. If i was able to help you.

[neuron]

Yes I agree its not only for Tris buffer. But there is no SDS in buffer still we get contamination. The thing is people in my new lab store all the buffers, including pH standards, tris buffer,phosphate buffers etc at 4 degrees. And the explanation is that if you store them at RT you get contamination . I googled for storage conditions for standard buffers, somewhere it was given that you store standard buffers at 4 degrees so that the evaporation rate of water is less and your pH is maintained ...

[bob1]

Contamination can come from many sources but is usually from spores or bacteria in the air and/or contamination while getting fluid out of the bottles.  Often small fibres seen the bottom of a bottle that do not proliferate are just dust, but ones that grow slowly are fungi.  pH standard buffers will never contain SDS and small volumes should be removed from the stock bottle for each calibration, rather than using the whole bottle.

[lyok]

Pangea, on 11 January 2013 - 06:59 AM, said:

Are the buffers bought from a company and is there SDS inside? One PhD in our Lab changed the whole Kit because she was not able to read. How stuipid, isnt?

Why is SDS so important for the contamination?

And PhD cant read? How you mean?

bob1, on 17 January 2013 - 12:00 AM, said:

Contamination can come from many sources but is usually from spores or bacteria in the air and/or contamination while getting fluid out of the bottles.  Often small fibres seen the bottom of a bottle that do not proliferate are just dust, but ones that grow slowly are fungi.  pH standard buffers will never contain SDS and small volumes should be removed from the stock bottle for each calibration, rather than using the whole bottle.

Again: why is SDS so important in this contamination problem?

Edited by lyok, 17 January 2013 - 12:22 AM.

[neuron]

SDS is dodecyl sulfate and that is one form of fatty acid. some of the bacteria use it as their food or energy source, thats what is my understanding lyok. AM I right? Please correct me if I am not

[leelee]

SDS can precipitate out of solutions at RT, so if buffers that do contain SDS have a whitish precipitate in them, some people can mistake if for contamination.

[lyok]

neuron, on 17 January 2013 - 03:37 AM, said:

SDS is dodecyl sulfate and that is one form of fatty acid. some of the bacteria use it as their food or energy source, thats what is my understanding lyok. AM I right? Please correct me if I am not

Ok.  
But isnt it also used to lyse bacterial cells? its a surfactant , right? SO the bacteria growing on this, are they special bacteria? (I mean: not very common bacteria or are a lot of bacteria able to grow on this?)

[bob1]

Not many things will grow in SDS containing solutions.  Some bacteria can grow in the presence of detergents, but these detergents are usually things like tween-20 which are weak detergents.  SDS is a strong detergent.

[lyok]

bob1, on 17 January 2013 - 11:47 AM, said:

Not many things will grow in SDS containing solutions.  Some bacteria can grow in the presence of detergents, but these detergents are usually things like tween-20 which are weak detergents.  SDS is a strong detergent.

Ok, this is what I was thinking!    

PS. is your avater the striped sun orchid? if so, then isnt the right name Thelymitra pulchella ?

[bob1]

lyok, on 17 January 2013 - 12:14 PM, said:

PS. is your avater the striped sun orchid? if so, then isnt the right name Thelymitra pulchella ?

It is - quite true, must have made a typo when I was making it my avatar.