In article 7d0 at decaxp.harvard.edu, ddeaguia at oeb.harvard.edu (Dan Deaguiar) writes:
>Hi all, I have recently begone wotking with yeast and I'm curious to know
>whether it is normal for them to grow to a limited size on sd media. I
>plate cells on sd media suplemmented with all aa's except the ones of
>interest and upon transformation i do obtain colonies. The problem is
>that after 5-6 days, the colonies reach 1-1.5mm in diameter and stop
>growing. This also occurs when I plate cells on sd supplemented with all
>aa's. Is this normal? Is there a problem with my media? I am making it
>according to Sherman's recipe...Might this be strain dependant (I am
>currently using one strain only)? Any insights would be appreciated.
Many strains of yeast have defects (e.g. in oxidative phosphorylation or TCA
cycle) which give them a small colony size, even when grown on rich media. Collectivley, they are called "petite" strains, due to that phenotype. Petites
usually will not grow on a non-fermentable carbon source, such as glycerol.
I would try replica plating onto SGly complete plates, to see if they grow under
those conditions. If not, you've probably got a petite strain, and there's nothing
wrong with your media. You can confirm this by growing another strain, which is known to grow well on SD or SGly, under the same conditions.