YEAST IN NO GRAVITY - THE INFLUENCE OF MICROGRAVITY ON CELLULAR ADHESIONS, BIOFILM
FORMATION AND IN INVASIVE GROWTH IN THE MODEL EUKARYOTE SACCHAROMYCES CEREVISIAE
(YEAST-B: PART 2)
Research Area: Microbiology
Expedition(s): 19 and 20
Principal Investigator(s): ● Ronnie Willaert, PhD, Vrije Universiteit Brussel, Brussels,
Belgium
● Freddy Delvaux, PhD, Katholieke Universiteit, Heverlee,
Belgium
● Jens Nielsen, PhD, Technical University of Denmark, Kongens
Lyngby, Denmark
● Lode Wyns PhD, Free University, Brussels, Belgium
RESEARCH OBJECTIVES
Yeast In No Gravity - The Influence of Microgravity on Cellular Adhesions, Biofilm Formation
and In Invasive Growth in the Model Eukaryote Saccharomyces cerevisiae ( Yeast-B: Part 2) will
determine the effect of microgravity on expression and functionality of Flo proteins from
Saccharomyces cerevisae, which are involved in cell surface interactions on solid substrate and
cell-cell interactions in liquid media. The final goal is to obtain information on the importance of
gravity on the formation of organized cell structures (flocculation, biofilm, invasion) and the
entire “Flo processes” itself.
RESULTS
The colony growth rate of the agar invasive S. cerevisiae Σ1278b strain was reduced as well as
its agar invasiveness. Postflight growth experiments of a brewer’s top yeast strain showed an
increase in G2/M and a decrease in Sub-G1
cell population; an increased viability, a
decreased lipid peroxidation level, increased
glycogen content, and changes in
carbohydrate metabolic enzyme activities
were also observed. Using the S. cerevisiae
BY4741 deletion collection, genes that
provide a survival advantage in space, were
identified in a batch growth experiment; no
difference in growth rate was observed.
Freeze-dried strains showed significant
changes in the cell wall thickness. Spaceflight
unique gene expression changes were
observed in stress response element (STRE)
genes with transcription regulation involving
Sfp1 (which is involved in the TOR pathway) and Msn4. Some of the components of the
ribosome biogenesis (which is under the control of Sfp1) as well as components of the
proteasome were down regulated in microgravity. Recent results indicate that microgravity
ISS020E044456 – Astronaut Frank De Winne,
Expedition 20 flight engineer, works with the Yeast-B
Part 2 experiment container in the Biolab incubator
located in the Columbus module.