forgot to add apmicillin

[billithecat]

I induced expression of a his-tagged protein in E.coli by adding ice cold LB with IPTG for 2 hours (and changing incubation temperature to 30 degrees from 37). Later I realised that I forgot to add ampicillin and chloramphenicol to the induction media. Would you go on and try to purify the protein from these cells anyway?

it's my first week at this new job and I guess I don't want to admit already that I made a stupid mistake....

[amberpdidit]

I would not continue since your protein yield may be WAY lower than expected since you haven't selected for your gene expressing bacteria. It is far more annoying to go through the entire purification than to just remedy a pretty simple situation.

I'm not sure what type of job it is but in my experience it is better to just put in the extra time (assuming you aren't getting paid overtime) and fix it. You aren't very deep into a mistake (should only need to reinocculate culture and induce) and chances are every scientist you work with has done something silly more than once. Better to establish yourself as someone who has intergrity in their work rather than leaving yourself to be exposed as someone who tries to get by.

[billithecat]

you got a point there...

I was just thinking that since the media is not totally devoid of ampicillin (I did have ampicillin and chloramphenicol in the LB before adding induction medium) and as the cells were shifted to lower temperature maybe they wouldn't lose the plasmid. Well, it is better to be safe than sorry...