Ever since I started homebrewing I have heard the odd comment about yeast eating the bacteria in the beer once fermentation is complete. I have searched high and low, and cannot find anything that remotely confirms this. Is this just a myth??
Yeasts eat bacteria? Myth?
- Thread starter theredben
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The pH and alcohol content of beer is not really conducive to yeast survival...
It's not true, that's for sure. Where have you heard this?
I have never ever ever heard this before, and I've been brewing for close to 14 years.
strat_thru_marshall
Well-Known Member
healthy fermentation pretty much will leave an environment that isn't favorable to bacteria, but yeast do not eat them...thats for sure.
rycov
Well-Known Member
i think its the byproducts (from fermentation) that they eat. clean up after themselves. never heard they eat bacteria.
Yeah, I've never heard that either.
theredben
Well-Known Member
I have only heard it a few times, but here is one (not so clear)example from a current thread:
"there is most likely some bacteria in your sanitized fermenting vessel just not the type the yeast cannot handle."
I was quite confident that was not the case, but was wondering if my googling skills needed some refreshing. Thanks.
Dunerunner
Well-Known Member
Not always, Lactobacillus can survive in a fully fermented beer, so can Pediococcus, Brettanomyces bruxellensis and Acetobacter.
theredben
Well-Known Member
My point exactly, I have seen brewing microbiology books reccomend plating 1.0mL of beer, and only if you have more than 10 colonies to start worrying. That is the problem with myths, you can find information suggesting those myths are not true, but not actually anyone proving it directly.
The yeast we use don't possess the cellular mechanisms necessary to ingest and digest an entire bacterium, so it's simply not true...
As for the bacteria in beer and yeast out competing them, it's mostly true. When the yeast are in full swing reproducing and gobbling up food, they are multiplying so fast that other organisms have a hard time getting going. Once the yeast slow down and settle out, other organisms have the opportunity to start up where your yeast left off.
As for the bacteria in beer and yeast out competing them, it's mostly true. When the yeast are in full swing reproducing and gobbling up food, they are multiplying so fast that other organisms have a hard time getting going. Once the yeast slow down and settle out, other organisms have the opportunity to start up where your yeast left off.
brokenseeker
Member
Perhaps they were implying that yeast could eat the dead micro-organisms if they were sufficiently broken down which could happen if they were not suited to the enviornment of beer. Still a bit of a stretch though since even if this did occur it would happen on such a small scale as to be insignificant, assuming the beer was good and not spoiled.
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