Taxonomy fun

Carol Hendrick hendrickca_nospam at phibred.dot.com
Sat Apr 4 13:38:07 EST 1998


I wonder if someone with a little more experience in yeast taxonomy
than I have can give us some insight-- and I hope you'll forgive me if
I'm a little hypothetical with the details (or if this kind of
question has already been discussed to death in this group).  We are
working on forage and forage additives and the things that cause
preserved silage to spoil when it is exposed to air.  Say that we have
isolated a strain of yeast and want to be able to give it the
appropriate name.  We sequence the 18S rRNA and come up with a
sequence that when checked against GenBank and the RDP database
matches very well with  both Saccharomyces XXX and Candida YYY, where
according to the texts, the Candida YYY is the asexual form of the
Saccharomyces XXX.   After many weeks of plating and waiting on
several different sporulation media, no spores have been seen.   The
Biolog yeast database gives a kind of poor match with Candida YYY, the
Saccharomyces XXX is not in that database.  

So the question is, do you need to see spores before you go ahead and
call something Saccharomyces?   Somewhere back in my aging
bacteriologist brain is the idea that Candida is the genus you put
things in when you don't have spores and don't know where else to put
them.  But if you have rRNA sequence that tells you it could be
Saccharomyces, could or should  that influence the ID?

Would appreciate any thoughts...

Best regards,

Carol Hendrick
hendrickca at phibred.com
Pioneer Hi-Bred International, Inc.
Johnston, IA





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