Those tiny bubbles.....(in YPD plates)

Michael Lichten lichten at
Thu Jan 18 08:14:50 EST 1996

I thought I would post a summary of replies to this message, as most folks
sent me email messages rather than posting them to the newsgroup.

In article <lichten-1701961527490001 at>,
lichten at (Michael Lichten) wrote:

> Recent batches of my YPD plates have many tiny bubbles in them, or what
> looks like tiny bubbles in the tetrad dissecting scope.  These bubbles are
> just a little bit smaller than a spore, so you can well imagine how much
> fun dissecting tetrads is on these plates. 

Many folks wrote suggesting that I flame my plates upon pouring.  Thanks
for that advice, but these bubbles are microscopic and are distributed
throughout the plates, not just on the surface.  I know how to avoid
surface bubbles.

Two other suggestions were made.  Ken Howe wrote:

Our lab makes tetrad dissection plates by passing the _hot_ YEPD through 
sterile disposible Nalgene 0.2micron filter flasks (no association with 
the company).  You'll need to use the pre-filters because they tend to 
clog easily, pull on maximum vacuum and pour quickly to avoid pouring 
lumpy plates.  Seems to work well for us.

And David Keszenman-Pereyra wrote:

I found bubbles in old plates kept at 4 C. I make plates for
dissection pippeting 15 ml of YPD at 55 C and then flame them.

I will test David's suggestion before Ken's!  

If anyone else has other suggestions, please let me know.  No more
flamers, please ;-)

Michael Lichten
lichten at

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