need help with lac- strain e.coli problem

Tom Dougherty Doughert at synapse.bms.com
Fri Apr 5 08:11:16 EST 1996

In article <31632C81.672C at calweb.com>, Matthew Chan <csv at calweb.com> says:
>I am sending this for a friend who is doing an individual experiment in 
>High School.  Message as follows:
>My name is Mike LeFevre and I am doing an experiment to try to test the
>mutation rate of E.Coli bacteria.  >snip<

There could be several problems.  If the particular strain of E. coli has an
outer membrane defect the dyes in the media will kill off the strain.  Also, what
kind of lac- mutation do you have?  Many lac- strains are deletions, and you
won't get any reversions with such a strain.  It is important that it be a point
mutation of some sort to get a reversion rate.  You also will get sectored 
colonies and need to decide how to deal with those in measuring your 
reversion rate.    Email if you need more details.
                                              Tom Dougherty

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