Hi,

I have a friend who desperately needs some nice ideas about a problem... He has some weird bacteria who are normally susceptible to Chloramphenicol, but he was able to isolate some spontaneously resistant clones on 50 ug/ml, and found out that a few of these clones are able to grow on up to 70 ug/ml of Cam. Now he wants to know how these clones are so resistant.

He has tried to clone this gene in E. coli and select for Cam resistant E. coli afterwards, which didn't really work. He has also sequenced the 23S to see if there is a mutation which prevents the Cam to bind to the large subunit, but this doesn't seem to be the case. He would try sequencing some efflux pump genes to see if there is a mutation there, but there are sth like 79 genes annotated as efflux pumps in the genome, and even more membrane proteins. There is no CAT of O-phosphorylase in the genome.

Anyone has a good idea how to come around this in less than a week?

thanks!