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Slow, energy-efficient, and mysterious life deep within Earth’s crust Karen
G. Lloyd, Associate Professor University of Tennessee -
2.9 x 1029 living microbial cells are buried in Earth’s
seafloor. Kallmeyer et al., 2012, PNAS -
2.9 x 1029 living microbial cells are buried in Earth’s
seafloor. That’s a third of the microbes on the planet. And 10,000 Imes more than the number of stars in the universe. Kallmeyer et al., 2012, PNAS -
2.9 x 1029 living microbial cells are buried in Earth’s
seafloor. That’s a third of the microbes on the planet. And 10,000 Imes more than the number of stars in the universe. Kallmeyer et al., 2012, PNAS -
2.9 x 1029 living microbial cells are buried in Earth’s
seafloor. That’s a third of the microbes on the planet. And 10,000 Imes more than the number of stars in the universe. Much of the life on Earth actually lives inside Earth. Kallmeyer et al., 2012, PNAS -
How do we learn about these deep subsurface microbes? •
We go out into nature and get samples. • We measure all the chemicals around them to see what they might be eaIng and breathing. • We extract their DNA or other biomolecules directly from a natural sample. • We bring them home and grow them in our laboratories. -
How do we learn about these deep subsurface microbes? •
We go out into nature and get samples. • We measure all the chemicals around them to see what they might be eaIng and breathing. • We extract their DNA or other biomolecules directly from a natural sample. • We bring them home and grow them in our laboratories. -
How do we learn about these deep subsurface microbes? •
We go out into nature and get samples. • We measure all the chemicals around them to see what they might be eaIng and breathing. • We extract their DNA or other biomolecules directly from a natural sample. • We bring them home and grow them in our laboratories. -
How do we learn about these deep subsurface microbes? •
We go out into nature and get samples. • We measure all the chemicals around them to see what they might be eaIng and breathing. • We extract their DNA or other biomolecules directly from a natural sample. • We bring them home and grow them in our laboratories. -
There are a LOT of different microbes on this planet.
Most of them don’t know how to kill us. -
There are a LOT of different microbes on this planet.
Most of them don’t know how to kill us. Yet. -
88 84 84 81 85 84 88 81 79 82
83 82 81 8 5 79 81 Same strain that some other microbiologist discovered -
88 84 84 81 85 84 88 81 79 82
83 82 81 8 5 79 81 Different strain, species, genus, family, order, class than anything that has ever been grown in a lab Same strain that some other microbiologist discovered -
Oerskovia Bacteriodales Desulfomicrobium Thioclava Agrobacterium Brevundimonas Psychrobacter Alkaliphilus Panibacillus Micrococcus
Kocuria 98 94 99 93 90 99 99 99 99 97 99 99 99 99 Isolates in liquid Same strain that some other microbiologist discovered Different strain, species, genus, family, order, class than anything that has ever been grown in a lab DNA sequences Data are all from ODP Leg 201: Parkes et al. 2005 Nature, Biddle et al. 2006 PNAS, Biddle et al. 2006 Geobiology, Batzke et al. 2007 Geomicrobiology Journal -
Oerskovia Bacteriodales Desulfomicrobium Thioclava Agrobacterium Brevundimonas Psychrobacter Alkaliphilus Panibacillus Micrococcus
Kocuria 98 94 99 93 90 99 99 99 99 97 99 99 99 99 Isolates on plates Isolates in liquid Same strain that some other microbiologist discovered Different strain, species, genus, family, order, class than anything that has ever been grown in a lab DNA sequences Data are all from ODP Leg 201: Parkes et al. 2005 Nature, Biddle et al. 2006 PNAS, Biddle et al. 2006 Geobiology, Batzke et al. 2007 Geomicrobiology Journal -
Isolates on plates Isolates in liquid Same strain that some
other microbiologist discovered Different strain, species, genus, family, order, class than anything that has ever been grown in a lab DNA sequences Data are all from ODP Leg 201: Parkes et al. 2005 Nature, Biddle et al. 2006 PNAS, Biddle et al. 2006 Geobiology, Batzke et al. 2007 Geomicrobiology Journal -
Isolates on plates Isolates in liquid Data are all from
ODP Leg 201: Parkes et al. 2005 Nature, Biddle et al. 2006 PNAS, Biddle et al. 2006 Geobiology, Batzke et al. 2007 Geomicrobiology Journal Same strain that some other microbiologist discovered Different strain, species, genus, family, order, class than anything that has ever been grown in a lab DNA sequences “Microbial Dark MaPer” -
• Microbes grow in cultures. • We know what microbes
do on this planet. Microbiology 101 -
• Microbes grow in cultures. • We know what microbes
do on this planet. -
Kallmeyer et al. 2012, Proc. Nat. Acad. Sci But, how
fast do they grow? -
Starnawski et al., 2017, PNAS They’re not really dividing and
making new cells at all! -
“It’s not a biome, Karen, it’s a die-ome.” -Jordan Bird,
in his first year as my PhD student -
If this ecosystem is just dying, why am I dedicaIng
my professional life to learning about it? -
So, WHAT does a microbial cell have to do to
“just exist” for thousands of years? -
Baltic Sea Sites in IODP Expedition 347 60 63 59
Jordan Bird Joy Buongiorno -
What are the potenIal mechanisms that allow bacteria and archaea
to persist in a near- zero growth state for 8,000 years, 50 meters deep into BalIc Sea sediments? -
Mixed environmental populaIon of microbes in whole sediments Physically separate
one cell Single cell genomics -
Mixed environmental populaIon of microbes in whole sediments Physically separate
one cell Break it open to get its genome Single cell genomics -
Mixed environmental populaIon of microbes in whole sediments Physically separate
one cell Break it open to get its genome Single cell genomics Copy its genome with an enzyme so there’s enough to sequence -
Mixed environmental populaIon of microbes in whole sediments Physically separate
one cell Break it open to get its genome Single cell genomics Copy its genome with an enzyme so there’s enough to sequence Sequence all the DNA -
Mixed environmental populaIon of microbes in whole sediments Physically separate
one cell Break it open to get its genome Single cell genomics Copy its genome with an enzyme so there’s enough to sequence Assemble genome in a computer Sequence all the DNA -
Mixed environmental populaIon of microbes in whole sediments Physically separate
one cell Break it open to get its genome Single cell genomics Copy its genome with an enzyme so there’s enough to sequence Assemble genome in a computer Sequence all the DNA Then you analyze the genes present in a microbe. Genes are like a menu for what the microbe is capable of doing. -
Anantharaman and Aravind 2013 Genome Biology Tuberculosis contains the same
amount of toxin- anItoxin systems -
Everyone’s starving, because the food is 8,000 years old. But,
that’s OK, because they are geneIcally programmed to avoid growing too fast. -
Everyone’s starving, because the food is 8,000 years old. But,
that’s OK, because they are geneIcally programmed to avoid growing too fast. So, what do they actually eat in order to stay alive for so long???? -
Depth (mbsf) UMP 4.6 14.3 77.92 74.72 68.02 54.82 48.3
43.15 37.4 7.65 14.3 78.3 67.05 60.4 53.9 47.25 40.65 20.85 Depth (mbsf) Bird et al., 2019, mBio -
Depth (mbsf) UMP 4.6 14.3 77.92 74.72 68.02 54.82 48.3
43.15 37.4 7.65 14.3 78.3 67.05 60.4 53.9 47.25 40.65 20.85 Depth (mbsf) Bird et al., 2019, mBio -
Atribacteria were the only microbes that could take up allantoin
from the environment and eat it. Depth (mbsf) UMP 4.6 14.3 77.92 74.72 68.02 54.82 48.3 43.15 37.4 7.65 14.3 78.3 67.05 60.4 53.9 47.25 40.65 20.85 Depth (mbsf) Bird et al., 2019, mBio -
If Atribacteria are the best at eaIng all the food,
then why they don’t just kill everyone else and “win” the deep subsurface game? -
Bird et al., 2019, mBio Atribacterial have a fully funcIonal
metabolism, including the ability to make all their own amino acids. -
Which of Atribacteria’s cellular processes was most heavily in-use? Look
at the metatranscriptomes Laura Zinke, USC Brandi Reese, Texas A&M Corpus ChrisI -
Bird et al., 2019, mBio The 2nd most acIve gene
in their genome encodes a protein that exports amino acids. -
Bird et al., 2019, mBio The 2nd most acIve gene
in their genome encodes a protein that exports amino acids. Maybe they get rid of their amino acids to keep from dividing? -
Bird et al., 2019, mBio The 2nd most acIve gene
in their genome encodes a protein that exports amino acids. Maybe they get rid of their amino acids to keep from dividing? This would have the effect of feeding the other organisms in the environment. -
How can adaptaIons to deep subsurface marine sediments arise when
there’s no chance to pass your genes along to the next generaIon? -
D. Giovannelli and P. Barcala Dominguez Maybe microbes come back
up early in the subducIon zones of volcanic arcs -
Inside an acIve volcano, Poas. Photo: D. Giovannelli Photo: T.
Owens Photo: C. PraE -
It’s hard to imagine life on other planets and moons
because they lack thick atmospheres. Our solar system may teem with subsurface biospheres. -
It’s hard to imagine life on other planets and moons
because they lack thick atmospheres. But nothing is stopping their subsurfaces from teeming with life!