Commercial Breweries Yeast

I am just curious how major commercial breweries like MillerCoors and Anheuser-Busch are able to use their yeast for so many years without it mutating. It is something that i always found curious.

Thanks in advance,

Chip

I imagine they have their own yeast laboratories to keep their strains healthy and pure.

Well, the idea is to keep pure cultures and grow from there. They have big labs that are keeping their yeast as steady as possible. And I assure you there's drift that is bound to happen even at the biggest of companies, but with such neutral lager yeast, you're talking miniscule shifts over time.

When dealing with population biology/ecology you have to assume variation exists. This is even assumed when dealing clones with the EXACT SAME GENETICS because the cells don't behave like clocks on the same rhythm with every other cell in the population. However that being said mutations are common events that can lead to disadvantageous, adventitious, or neutral changes in the mutated cell. More often than not the mutations are disadventagous to the cell - where it will die or be likely outpopulated by healthy clones. These mutations can arise from any number of cases from DNA damage to a mistake by a DNA Polymerase when replicating the genome. So with that being said breweries order from these large labs where the and/or the brewery do constant Quality Control checks of the yeast. If the yeast comes from bad stock that is say for example ethanol intolerant at low levels of ethanol (4%), then the brewery wouldn't use the parent batch at all or they wouldn't sell that beer. That's my thoughts on it though - I have never worked in a brewery, but I do plenty of lab work and have seen other industrial applications of food microbiology.