Checking for contamination in yeast strains, media, water, and lab surfaces 06Oct2014

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We're getting colony growth on *all* of our media, including apparent growth of our two URA- yeast strains on the CM uracil negative medium. Under the microscope, the cells look like yeast. *Something* must be getting contaminated, likely with WT S. cerevisiae from the lab, or environmental yeast strains. We should test all possible sources of contamination, including water sources, test for yeast on various surfaces, etc.


  • open in air on bench, 1hr
  • open in air inside BSC, 1hr
  • 10ul of yeast droplets on plate
  • 10ul water droplets
  • swab all surfaces, and streak on plate in quarters
    • one plate for bench surfaces
    • one plate surfaces inside BSC
    • one plate for others: pipetters, gloves, pipette tips,
    • on plate for handles: fridge, cabinets, drawers,