Hi Yeasters,
Another query relating to the growth of yeast cultures. I have
recently realised that the source for innocula of overnight cultures may
play a significant role in determining how fast the cultures get going:
what determines lag times?
I tend to innoculate all cultures from fresh plates - more or less
straight from the incubator, or from plates kept at RT for a day or two beyond
the "30 degrees for two to three days" which is typical for culturing colonies
on agar. The plates are either minimal (SD) or rich (YEPD) media; in the latter
case the colonies may have been cultured successively upon agar for several
months, but I get the same effects from cells plated from glycerol stocks.
The difference which I see is in the amount of growth from an O/N
culture in minimal media (16-18 hrs, accurately timed from innoculation the
afternoon before). When the innoculum is obtained from SD plates, the amount of
growth is typically 50-100 fold of the primary innoculum. However, when the
yeast have been grown on YEPD agar, the increase is much less: about 10-fold.
Moreover, following the cultures for a few hours suggests that the cells are
not growing very fast until about 14-16 hours after innoculation, at which time
they reach OD600 doubling times of less than 100 minutes (the strain is HF7c),
which is quite impressive in minimal media.
Has anyone else observed these sort of innoculum-dependent behaviours
or seen references pertaining to the culturing of yeast which might shed light
on this aspect of yeast work?
Thanks for your help
Clem Stanyon
