Maxiprep woes

[matt_ambros at hhs.dresden.k12.nh.us]

Another reason there is no DNA in your sample could be that when you grow 
larger quantities of cells, you are losing your plasmid. Have you tried growing 
with sulbactim plus AMP which keeps the bacteria which have lost the plasmid 
from growing because it scavenges the b-lactamase? I had delicate cosmids that 
deleted all the time and had to grow them as dozens of 10 ml cultures which I 
then pooled to get tiny amounts of DNA. So in reality, there may be nothing 
wrong with your miniprep procedure.
Candy Lee