Ale yeast still fermenting in fridge

[danglebell]

I kept the yeast which came with a bulldog brew ale kit since it seemed to work well (sachet was labelled pacific, had a look and possibly a white labs yeast) and I've used it for quite a few brews since, I keep it in the fridge when it's not in use but the problem is this yeast is still fermenting! After the first use I wasn't airing it and noticed some time later that the lid of the container was bulging so rushed to loosen the clamp and release air, which took many attempts because of how much there was and it frothing up the liquid out, so now I air it every so often. But even now, it's not been used in about 2 weeks and is still building up gas I have to release every few days - what is going on here? The original brew was finished (I've been drinking it!), it had a mix of sugar and malt so is this the yeast slowly breaking down the malt? And why is this ale yeast still fairly active at 5c when that's way below the optimal 18-25c temperature?

 

[Slid]

I routinely re-use yeast by decanting the trub into 250ml bottles and even though I seem to get very good attenuation, the 250ml bottles keep fermenting at 3 Celsius in the fridge. Same for every yeast I have ever re-used, not that there are many of them, so US05, Abbey Yeast, Saison, Wheat yeast, Nottingham and others, all will ferment over a month or two.

The ones that had "finished" fermenting 3 months previously absolutely explode out of the bottle after 3-4 months later, when I finally chuck the contents.

 

[MashBag]

Yeast will keep working.
Bottle it.

 

[danglebell]

Yeast will keep working.
Bottle it.

It's in a spare collection vessel for the fermenter (the other one is currently attached with lager yeast). Interesting, did not know ale yeast worked at these low temperatures, why I thought it was summer-time usage only

 

[MashBag]

It continues to work just slower, just like animals hibernate in the cold.