I'm doing a yeast display experiment and have been sorting yeast cells (S. cerevisiae) with a BioRad cell sorter.
In the later rounds I've started getting contaminants on the plates. Some plates do not have any contaminants at all. In other instances it's quite possible that the contaminant is being passaged along with the sorted cells (although I'm gating a double positive population...)
The colonies have a raised margin and in some instances a "button" in the middle. The attached pics have a 200 ul pipette tip for scale; there are also some typical S. cerevisiae colonies visible in the images.
Details:
Plates: synthetic complete - trp, dextrose, pen-strep. ~2 weeks old and stored at 4C.
Growth: 2 days at 30C. Incubator is also used for E. coli plates.
Yeast strain: S. cerevisiae BJ5465
Plasmid: gal promoter so there should be no cell surface display of the DARPin library.
Cell sorter: BioRad S3. The sorting chamber is not sterile. Only yeast cells have been sorted recently although some Corynebacterium cells were analyzed in the same time frame (different days though) that yeast were sorted.
Thanks for any ideas!
Cual es el proposito de su investigacion?
Si es su trabajo con la cepa, deberia repetir el experimento evitando la contaminacion de muestras
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