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Too much LB in medium


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12 replies to this topic

#1 lyok

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Posted 26 February 2014 - 02:51 AM

Hallo,

 

I have a quick question: I used the double amount of LB (the flask said 10g/l) I accidently used 20g/l.

 

Now I wonder: does this make a difference? I would think not, its just more food for the bacteria. But what about antibiotics you use? Would this perhaps be a problem or should it not be a big problem?

Altough, I can imagine that because of the more food present the bacteria that have not been transformed like they should have been, perhaps are able to grow due to the excess in food?

 

I am also assuming that the salt concentration , although being doubled does not really play a huge role.

 



#2 phage434

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Posted 26 February 2014 - 05:53 AM

Why not simply dilute it by a factor of two.



#3 lyok

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Posted 26 February 2014 - 09:54 AM

Too late, already poured the plates.



#4 bob1

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Posted 26 February 2014 - 12:19 PM

Salt can play a huge role in this - the osmotic strength of the solution is very important for bacterial growth.  Too much and the bacteria will dehydrate and not grow...

 

Best to throw out and make some fresh plates.



#5 phage434

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Posted 26 February 2014 - 01:41 PM

I agree with Bob1.



#6 Phil Geis

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Posted 26 February 2014 - 07:26 PM

Be rigorous in your science.  



#7 bob1

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Posted 26 February 2014 - 10:50 PM

Be rigorous in your science.  

This...this is good advice always!



#8 perneseblue

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Posted 27 February 2014 - 08:13 PM

Aside form being too salty to grow, some antibiotics are salt sensitive and will not work in high salt environment (ie, Kanamycin, blasticidin and hygromycin).


May your PCR products be long, your protocols short and your boss on holiday

#9 lyok

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Posted 28 February 2014 - 10:41 AM

Interesting!

Where do you get this knowledge ?

Is it mentioned in the papers you get with the antibiotics?

 

Aside form being too salty to grow, some antibiotics are salt sensitive and will not work in high salt environment (ie, Kanamycin, blasticidin and hygromycin).

 

 



#10 perneseblue

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Posted 28 February 2014 - 08:16 PM

You can find such interesting information and more in, molecular Cloning: A Laboratory Manual, Maniatis.


May your PCR products be long, your protocols short and your boss on holiday

#11 lyok

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Posted 05 March 2014 - 01:36 PM

My question makes me wonder: what if you have less of the LB?

Than the salt can not be a problem I guess (not too much salt, so no stress or problems with antibiotics).

Or is a low salt content also a big stress? (I can image not enough nutrients, so slower growht, but for the rest?)

 

 



#12 bob1

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Posted 05 March 2014 - 01:38 PM

Osmotic stress at lower concs!



#13 perneseblue

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Posted 05 March 2014 - 09:15 PM

You can lower salt concentration to 50mM NaCl for E coli, without effecting cell viability.

However the lower the salt concentration, the lower the growth rate.

 

I use 5g/L NaCl (85mM) in my LB (standard low salt LB).

At this concentration, the growth rate is a bit lower but not generally noticeable in overnight cultures and in some circumstances ( ie BAC cultivation) this slower growth rate is desirable. No problem with salt sensitive antibiotics either.


May your PCR products be long, your protocols short and your boss on holiday




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