Expert: Walter Hintz - 2/7/2007

Question
Hello,
I am trying to grow E. coli K-12 for my science project but it's not growing.  Here is my procedure: First, I poured plates with nutrient agar.  Then I swabbed and created a lawn on about 40 plates with E. coli in a tube (the e. coli in the tube is with nutrient broth).  Next, I put the plates in an incubator for 24 hours at 37 degrees Celsius.  When I checked them the next day there was no E. coli on any of the plates.  I thought maybe the E. coli needed more time to grow so I kept it in the incubator for 24 more hours.  Still, nothing grew.  I tried this same procedure several times using different E. coli cultures.  Do you have any idea of why the E. coli could not be growing?

Answer
Hi Kristin
 There are two ideas that come to mind. One is that the broth culture was not viable.  The other is that the original culture that went into the broth was not.  Was the broth that you transferred to the plates cloudy. Also,Nutrient broth is not a good medium for a gram negative.  If you can do so try to get some McConkeys or EMB agar