Overexpression of cell wall proteins causes flocculation and adherence
to the agar. (A) Ten-milliliter cultures of yeast
strains were grown in YPGal overnight, swirled briefly in a Vortex
mixer, and photographed immediately and after 30, 60, and 90 min
(numbers to the right). Yeast strains: 1, wild type (10560–2B); 2,
flo11 (WY168); 3, flo11 GAL1-FIG2
(WY297); 4, GAL1-FLO11 (WY334); 5, flo11
GAL1-FLO10 (WY341); and 6, flo11 GAL1-FLO1
(WY340). (B) The same strains used in A
were patched to YPD or YPGal plates. After incubation for 5 days, the
plates were washed under a stream of water and rephotographed. The
wild-type strain is less invasive on a YPGal plate than on a YPD plate.
(C) The same strains used in A were grown
in YPD or YPGal liquid medium overnight and swirled briefly in a Vortex
mixer, and a fraction of the cells were spotted on an agar (2%) plate.
The plate was let dry for 30 min, washed, and rephotographed. The
flo11 GAL1-FLO1 strain looks denser on the unwashed
plate because the cells are flocculent and stick together in large
clumps.