Microbes are awesome, says biologist Paula Welander. They have shaped Earth’s chemistry and its environment over billions of years, including oxygenating the planet to make it habitable for larger life forms. In turn, microbes have been shaped by that very same environment, evolving as the climate has evolved, she says. Welander now studies the lipid membranes of ancient microbes, which can endure for millions of years, to understand this evolution and where we might be headed in the future. Microbes are our connection to the ancient world, Welander tells host Russ Altman on this episode of Stanford Engineering’s The Future of Everything podcast.
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Chapters:
(00:00:00) Introduction
Russ Altman introduces guest Paula Welander, a professor of Earth Science at Stanford University.
(00:04:06) Why Study Microbial Lipids
Why lipids are essential for modern microbiology and Earth’s history.
(00:05:19) Diversity of Microbial Membranes
How bacteria and Archaea build different kinds of membranes.
(00:07:15) Reconstructing Ancient Environments
Using specific lipid biomarkers to understand the early planet.
(00:09:20) Chemical Fossils vs. Organism Fossils
Why microbes don’t leave traditional fossils—but their lipids do.
(00:10:55) Lipids as Environmental Clues
How certain lipids indicate the environments organisms lived in.
(00:12:36) Archaea: A Distinct and Ancient Entity
Archaea’s evolutionary importance and chemically distinct membranes.
(00:15:43) The Lipid Divide
Why eukaryotic membranes resemble bacterial, not Archaeal, membranes.
(00:17:12) Tracing Membrane Evolution
Recent breakthroughs in studying Archaeal lineages related to eukaryotes.
(00:19:11) Lipid Preservation Over Time
How archaeal lipids are especially reliable as long-term biomarkers.
(00:20:58) Sterols as Biomarkers
The role sterols, including cholesterol, play in lipid archeology.
(00:23:14) Bacterial Cholesterol Discovery
The discovery that a rare bacteria can synthesize sterol precursors.
(00:25:02) Functional Roles of Bacterial Sterols
The possible roles sterols may play in microbial membranes and cell function.
(00:26:31) Archaea in the Human Gut
The number and types of Archaea found in the human microbiome.
(00:28:43) Archaea and Antibiotics
Whether Archaea react similarly to bacteria when exposed to antibiotics.
(00:29:46) Future In a Minute
Rapid-fire Q&A: hope, research needs, and alternate career dreams.
(00:31:43) Conclusion
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