Thanks to all of you who responded to my letter. This is what we know
about the organism:
It is most likely Sporobolomyces salmonicolor, a yeast known to produce
"ballistospores". There is a picture of it at
This is what I have ascertained about its behaviour so far.
* it grows best at 30 degrees celsius
* no spores are released on rich nutrient broth after 24 h growth. Only
simple budding growth is observed.
* the ballistic response is induced by a lack of nutrients (but not
carbon or nitrogen).
* tranferral of cells from rich medium to a synthetic minimal medium
(especially one that contains all amino acids) leads to massive 'spore'
generation. Almost every cells produces a ballistospore in 2 hours -
spores are thrown after 2.5 h. It is impressive to watch.
* Complete YPD Saccharomyces cerevisiae medium induces a meager
ballistic response: the response is delayed 7 h and 'spores' are not
thrown as far.
* S. cerevisiae sporulation medium (low nutrient/acetate C-source)
induces a pseudohyphal stage - but not "ballistospores".
DOES ANYONE KNOW
A. What is known about the mechanism of launching spores. Is it a
torsional stress like in plant seed pods or is it an active (actin?)
A Medline search only found theoretical papers from 1968 and 72.
B. Is this a diploid organism woth a haploid stage?