"The yeast of our problems" joke

I found the following professionally printed handbill posted on a door
in the Georgetown physiology department.
Did you know?
EVERY TIME A LOAF OF BREAD
IS BAKED,
APPROXIMATELY
150,000,000 YEASTS ARE
KILLED.
Come to the award-winning 1987 film,
"The Very Small and Quiet Screams"
- a cinematic electromicrograph of yeasts being baked.
"A must for those who care about yeast,
and especially for those who don't."
Evening showing in Johnson & Wales
Pirsig Auditorium: 7PM, 4/19
SPONSORED BY
Brown Anaerobe Rights Coalition (BARC)
Student Bakers for Social Responsibility
Coalition for the ELevation of Life (CELL)
Campus Crusade for Fetal Matters
Defend all life: "from greatest to least, from human to yeast!"
This poster printed on 100% yeast-free paper.