Infected wort?

I placed 4 gallons of hot wort in a carboy and corked it with a solid bung; it cooled to room temperature. I then transferred the cool wort to another carboy that has a thermometer strip on it, sealed it with a solid bung. (I sure this is when the infection happened.) The next day, the bung blew off and foam had formed on top of the wort. I haven't pitched the yeast yet. Can I reheat this wort and kill the wild yeast/bacteria?

Edited post, reread your OP a bit more.

How far did the gravity move in the day that this occurred? If you haven't lost too much gravity, I 'spose it's possible to heat it.. Depends on the infection though, they can leave behind some nasty off flavors depending on which bad guys got in.

First off, bad idea on putting hot wort in (what I assume) is a glass carboy. Thermal difference inside vs. outside can cause cracking and failure. Just think what would happen if you were carrying that carboy and it shattered....hot wort + shards of glass = not good.

As it is you may have weakened the glass structure of the carboy (microcracks). All depends on how hot that wort was...

Sounds like you have an infection going on, Shroomz idea of a hydrometer check will tell you for sure.

You can boil to kill the bugs, but any off-flavors from their activity will be left behind.

Thanx Shroomz and Broadbill. Your input is helpful.

Also, as a rule...try not to transfer cooled wort if you can help it. I chill right into the fermenter and there it stays until fermentation is complete. I know a lot of the 'no chill' brewers might have some insight on this, but this is an easy thing to eliminate if you can.

With infected wort either let it ride and see if something good happens to come of it (but be prepared to sit on it for over a year) OR just dump it. Reboiling and such will just result in wasted time and effort.