normally i go from plate colony to starter culture and add 1mM antibiotic concentration to my starter culture. antibiotic being ampicillin. unfortunately i forgot this time and was wondering how bad it might be going from starter culture to big culture? The big culture will also have antibiotic ampicilllin added to it in 1 mM concentration. I did keep everything asceptic as possible, flamed neck of flask repeatedly and kept everything as close to the flame as possible and only opened flasks for the briefest periods of time when needed. I also virkon, ethanolled and dephaged my bench on friday so was owndering if that would be asceptic enough to prevent unwanted micro-organisms from growing. i might go in early and add antibiotic to the starter culture tomorrow morning to just kill off some micro-organisms that shouldnt have grown but did, so was wondering how long ampicillin takes to act?

Adding the antibiotic in the next day should work. Antibiotics don't take long to work in culture.

The bacteriocidal action of antibiotics is concentration-dependent, but at the concentrations of Amp used in the lab (e.g., 50-100ug/ml) evidence of bacterial death is observed within hours, although a very small proportion of bacteria can be Amp-resistant (e.g., on agar plates you may observe Amp-resistant bacterial satellites surrounding colonies).