Infection - What is it?

[Douglefish]

I made 10 gallons of Russian Imperial Stout about 3 months ago. Fermented it out and transfered to secondary in 2 5 gallon carboys. I let them set in secondary at room temp for a couple of months and didn't really check much on them. I did however put a carboy cap on 1 of them, and saran wrap on the other. Last night I went to bottle and found the carboy cap to be popped off and a noticeable white film about 1/8" thick covering the entire carboy. There definitely was a chance for things to fall into the beer. There were no bubbles, and the film looked very dusty and uniform.

My buddy said it was acetobacter, but I have no idea. I didn't bottle that one but put it into the keg and am force carbing at fridge temps to slow down the infection. I also tasted it and it tasted and smelled fine? When comparing to the non-infected portion it was a little thinner tasting and a lot of the roasty flavors of the stout were subdued. No vinegar taste?

I didn't have a camera or I would have taken a picture.

Any idea as to what this may have been?

 

[Bowtiebrewery]

could be acetobacter however what i would do to check and see if the whole batch is infected is go ahead and siphon off some of the beer from the bottom and put in a glass and cover it with some plastic wrap... or if you have a borosilicate lab flask that can have a stopper put in it with an air lock use that instead... Wait a couple days and if the film re-forms... you have infected beer.