Baker's yeast () is well-known for its role in baking, brewing and modern biotechnology. Yet this on a regular basis microorganism may additionally offer insight right into a much larger query: how life can withstand the intense conditions found outside of Earth.
Researchers from the Department of Biochemistry (BC) on the Indian Institute of Science (IISC), working with colleagues on the Physical Research Laboratory (PRL) in Ahmedabad, have discovered that yeast can survive atmospheric pressures much like those on Mars. Their findings suggest that even easy life forms could also be more resilient to environmental conditions than previously thought.
Simulating Mars with shock waves and toxic dust
To test yeast survival, the research team subjected living cells to severe physical and chemical stress. These experiments include exposure to powerful shock waves comparable to those produced by meteorite impacts on Mars, in addition to perchlorate salts, that are toxic compounds present in Martian soil.
The shock waves were generated using a High Intensity Shock Tube for Astrochemistry (HISTA) positioned in Bhallamurugan Sivaraman's laboratory at PRL. These waves reached speeds of as much as Mach 5.6. In addition, yeast cells were treated with 100 mM sodium perchlorate, either alone or together with shock wave exposure.
Overcoming experimental challenges
Setting up the experiments posed major technical difficulties. According to the researchers, exposing living yeast cells to shock waves at this intensity had never been done before.
“The biggest hurdle was setting up the histatube to expose living yeast cells to shock waves,” explains Riagoro, a project assistant lead creator within the lab of Portseth I Riagoro, associate professor at BC.
How Yeast Survived Extreme Stress
Despite the tough conditions, yeast cells survived exposure to shock waves, perchlorate salts, and even each stresses together. While their growth slowed, survival rates remained high.
The researchers consider that this flexibility derives from the yeast's ability to form ribonucleoprotein (RNP) condensates. These are small membraneless structures that help cells protect and reorganize mRNA when stressed. Exposure to shock waves caused yeast cells to form two varieties of RNP aggregates called stress granules and Pbodies. When exposed to perchlorate salts alone, cells formed P bodies. Yeast strains that lacked the flexibility to form these structures were much less prone to survive.
Biomarkers for all times in alien conditions
The results suggest that RNP conjugates may act as biomarkers, or biological indicators, of cellular stress within the extracellular environment. This provides scientists with a possible tool to discover how life responds to extreme conditions outside of Earth.
“What makes this work unique is the integration of shock wave physics and chemical biology with molecular cell biology to investigate how life can cope with such stresses on Mars,” says DHAG.
Implications for astrobiology and space exploration
This study highlights baker's yeast as a strong model organism for India's growing astrobiology research efforts. By studying how yeast regulates the reorganization of its RNA and proteins when exposed to mechanical and chemical stress, scientists can gain helpful insight into how life forms might survive on other planets.
This insight could also aid in the event of biological systems designed to face up to the intense environment in space.
“We were surprised to observe yeast surviving stressful conditions like Mars,” says Rajyaguru, corresponding creator of the study. “We hope that this study will advance future space exploration efforts in Khmer.”