[Microbiology] yeast s288c growth

[Juha Parviainen]

Hi,

I'm growing yeast strain S288C (MATalpha trp1-0) in 2L fermentor. The 
medium is YEPD and the setup is as follows:
  - fermentation type: batch
  - temperature: 30 'C
  - initial pH: 4.8 (pH is not controlled)
  - airflow (1.12 L/min) and stirring (300 rpm) are kept constant.

My "problem" is that I'm getting unusual pH- and pO2 curves compared on 
what I have been used to in fermentations of typical bakers yeast.
Please, look the picture 
http://hytti.uku.fi/~jpparvia/joutavia/growth_curve_s288c.png
I'm wondering what happens in about 20 hours after inoculation. There are 
sharp changes on both curves. Could someone share an opinion?


Regard,

---------------
J Parviainen