Yeast Starter - Growth Factor

[droder1]

All,

I feel this is a topic that hasn't been explicitly hit on, at least not that I can find (be it here on HBT, Mr Malty, YeastCalc or in the Yeast Book). What is everyone's maximum, or comfortable, "growth factor" when creating a yeast starter? This is especially interesting to me / pertinent, when growing yeast from harvested cultures.

Mr. Malty allows for a growth rate between 3 and 6, but doesn't say why. The yeast book has an optimum inoculation rate, and says you don't want to have too high of a growth factor/rate, but doesn't give a max.

Simplified example, if you start with 100B (assuming fully viable), and want to get to 1 trillion cells, where would you feel comfortable, maybe more importantly, what is known to be an ideal maximum growth rate? A 6.4L starter would get you to 1T cells, but the growth factor would be 9.02.

My rule of thumb is a growth factor around 3 with decent sized starting cell counts, and sometimes up to 6-8 if I am starting with a very low, or estimated cell count. But I cannot find much to support why this should my rule of thumb.

Thoughts/insight?

Cheers all.

 

[droder1]

Nothing?

 

[flars]

I have had the same question. Could not find any verified information. I just decided to not go over a growth factor of four to negate the possibility of stressing the yeast.

 

[NeverDie]

I have almost the same question, but instead of "what is the maximum", I would like to know what is a conservative growth factor to assume? i.e. what is a growth factor that one can rely upon happening when doing these calculations? If the actual growth factor turns out to be higher, then all well and good, but if you over-estimate the growth factor, and it turns out to be less, then you've defeated yourself because your yeast starter won't be potent enough.

Assuming a stir plate, is a growth factor of 3 reasonably conservative? For what time frame and under what conditions?