1. Bacteria generate biomass without water
in desert ecosystem
이동희
최유미

2. 1 2 3
Introduction
Results
Conclusion and future directions

3. Introduction 20% Range of Desert Planet’s terrestrial land surface
cover one-fifth of the planet’s terrestrial land surface (33.7 X106 km)
Planet’s terrestrial land surface

4. Introduction Definition of Desert
having a precipitation to evapotranspiration ratio(P/ET) of less than 1
Sub - humid
Semi - arid
Arid
Hyper - arid
(0.5 – 0.65)
(0.2 – 0.5)
(0.05 – 0.2)
(<0.05)

5. Introduction Multiple physicochemical pressures
Water deficit
Organic carbon deficit
UV radiation damage
Extreme temperature variations
Despite
Abundance and diversity microorganisms

6. Introduction
Figure 1. Bay, S., B. Ferrari, and C. Greening Life without water: how do bacteria generate biomass in desert ecosystems? . Microbiology Australia. 1)

7. Introduction Primary producer Actinobacteria Proteobacteria
Acidobacteria
Actinobacteria
Primary producer

8. Common region In dryland
Introduction
Common region
In dryland
- combined effects of water deficit and damaging UV radiation inhibit photosynthetic processes and in turn limit primary production in arid and hyper-arid desert ecosystems
- organic carbon derived from photosynthetic primary production is a major energy source for the heterotrophic
microorganisms

9. A minimalistic mode of primary production
Introduction
A minimalistic mode of primary production
photosynthetic
Atmospheric gases
chemosynthetic
Energy source

10. Terrabacteria Enzymes
Introduction
Terrabacteria
Actinobacteria
Chloroflexi
WPS-2(Candidatus Eremiobacteraeota - desert bacterial phylum)
AD3(Candidatus Dormibacteraeota dormant bacterial phylum)
encoding
[NiFe]-hydrogenase and Carbon monoxide dehydrogenase
Facilitate trace gas scavenging to support persistence of heterotrophic bacteria under organic carbon starvation
Enzymes
Gas Chromatography
H2 ⇄ 2H+ + 2e-
CO + H2O +A ⇄ CO2 + AH2 ↓

11. Calvin Benson-Bassham(CBB) cycle
Introduction
Calvin Benson-Bassham(CBB) cycle
14C
Tracing assimilation of 14C-labelled CO2 by atmospheric gases in microcosm experiments
Under desert conditions, (H2↑, light↓)
chemosynthetic CO2 fixation
increased up to tenfold

12. Results
Figure 2. Neilson, J. W., K. Califf, C. Cardona, and J.G. Caporaso Significant Impacts of Increasing Aridity on the Arid Soil Microbiome. Applied and Environmental Science. 2)

13. Results (1- Aridity index)
Figure 3. Fernando T. Maestre, Manuel Delgado-Basquerizo, and Thomas C. Jeffries Increasing aridity reduces soil microbial diversity and abundance in global drylands. PNAS. 4)

14. Results (1- Aridity index)
Figure 4. Fernando T. Maestre, Manuel Delgado-Basquerizo, and Thomas C. Jeffries Increasing aridity reduces soil microbial diversity and abundance in global drylands. PNAS. 4)

15. Conclusion
Figure 5. Bay, S., B. Ferrari, and C. Greening Life without water: how do bacteria generate biomass in desert ecosystems? . Microbiology Australia. 1)

16. Future directions Managing desertified regions
Search for extraterrestrial life on planets (ex. Mars)
Development of new technology
Understanding the physiology and biochemistry of trace gas scavenging
using pure bacterial cultures and purified enzymes

17. Reference
Bay, S., B. Ferrari, and C. Greening Life without water: how do bacteria generate biomass in desert ecosystems? . Microbiology Australia.
Neilson, J. W., K. Califf, C. Cardona, and J.G. Caporaso Significant Impacts of Increasing Aridity on the Arid Soil Microbiome. Applied and Environmental Science.
He, S., S.A.Malfatti, J.W. McFarland, and F.E. Anderson Patterns in Wetland Microbial Community Composition and Functional Gene Repertoire Associated with Methane Emissions.
Fernando T. Maestre, Manuel Delgado-Basquerizo, and Thomas C. Jeffries Increasing aridity reduces soil microbial diversity and abundance in global drylands. PNAS.

18. Thank you for your attention