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Bioweek talk 2012

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EXTINCTION OF MICROBES... SHOULD WE CARE? Marilen M. Parungao-Balolong, MSc, SMic Associate Professor Bioweek 2012 BIOSeminar Wednesday, August 15, 2012
Transcript
Page 1: Bioweek talk 2012

EXTINCTION OF MICROBES... SHOULD WE CARE?

Marilen M. Parungao-Balolong, MSc, SMicAssociate Professor

Bioweek 2012 BIOSeminar

Wednesday, August 15, 2012

Page 2: Bioweek talk 2012

WE ALWAYS CARED ABOUT PLANT EXTINCTION

Wednesday, August 15, 2012

Page 3: Bioweek talk 2012

WE ALWAYS CARED ABOUT ANIMAL EXTINCTION

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Page 4: Bioweek talk 2012

WE ALWAYS CARED ABOUT HUMAN EXTINCTION

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Page 5: Bioweek talk 2012

BUT...MICROBES? ALWAYS TAGGED AS

THE REASON FOR EXTINCTION...

Wednesday, August 15, 2012

Page 6: Bioweek talk 2012

MICROBES: THREAT TO PLANTS

Phytophthora infestans = Europe and Ireland, (1840)

Hemileia vastatrix or coffee rust Ceylon (1860s)

Cratocyctis ulmi = Dutch Elm Disease (1900s)

Wednesday, August 15, 2012

Page 7: Bioweek talk 2012

MICROBES: THREAT TO HUMANS

BLACK DEATH & SPANISH FLU

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Page 8: Bioweek talk 2012

MICROBES: THREAT TO ANIMALS

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Page 9: Bioweek talk 2012

CAN MICROBES FACE EXTINCTION?

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Page 10: Bioweek talk 2012

“Extinction is a Principle of Evolution”

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Page 11: Bioweek talk 2012

EXTINCTION

• Over 99% of the species that have ever lived have become extinct

• Guesstimate: we lose about 1 species per day

• CURRENTLY: they say that we are living in a period of mass extinction (6th) = brought about by human activity as driving force

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Page 12: Bioweek talk 2012

“Microbes are Everywhere”

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Page 13: Bioweek talk 2012

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ca. 4 to 5 × 1030 prokaryotic cells on Earth, with the open ocean, soil, and oceanic and terrestrial

subsurface showing the highest abundances

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Page 16: Bioweek talk 2012

A typical coastal water sample contains 107 viruses, 106 bacteria and

103 protists /ml

Wednesday, August 15, 2012

Page 17: Bioweek talk 2012

Microbes come in diverse forms; however, it is not known how many different species of microbes inhabit the planet....WHY?

Wednesday, August 15, 2012

Page 18: Bioweek talk 2012

Microbes come in diverse forms; however, it is not known how many different species of microbes inhabit the planet....WHY?

• problems involved in defining a microbial species

Wednesday, August 15, 2012

Page 19: Bioweek talk 2012

Microbes come in diverse forms; however, it is not known how many different species of microbes inhabit the planet....WHY?

• problems involved in defining a microbial species

• majority of prokaryotic cells cannot be easily grown in culture, which is a prerequisite for species identification of microbes

Wednesday, August 15, 2012

Page 20: Bioweek talk 2012

Microbes come in diverse forms; however, it is not known how many different species of microbes inhabit the planet....WHY?

• problems involved in defining a microbial species

• majority of prokaryotic cells cannot be easily grown in culture, which is a prerequisite for species identification of microbes

• NOTE: Only about 5000 to 6000 prokaryotic species have been formally described

Wednesday, August 15, 2012

Page 21: Bioweek talk 2012

With the birth of NON-CULTURE METHODOLOGIES....

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Page 22: Bioweek talk 2012

With the birth of NON-CULTURE METHODOLOGIES....

• At least 1800 species and 1.2 million new genes were found using a shotgun sequencing approach of microorganisms from a single sample in the Sargasso Sea (Venter et al. 2004)

Wednesday, August 15, 2012

Page 23: Bioweek talk 2012

With the birth of NON-CULTURE METHODOLOGIES....

• At least 1800 species and 1.2 million new genes were found using a shotgun sequencing approach of microorganisms from a single sample in the Sargasso Sea (Venter et al. 2004)

• About 643 new species were identified using a 99% similarity as delineation between prokaryotic phylotypes or species based on 16S rRNA gene sequences (Venter et al. 2004)

Wednesday, August 15, 2012

Page 24: Bioweek talk 2012

With the birth of NON-CULTURE METHODOLOGIES....

• At least 1800 species and 1.2 million new genes were found using a shotgun sequencing approach of microorganisms from a single sample in the Sargasso Sea (Venter et al. 2004)

• About 643 new species were identified using a 99% similarity as delineation between prokaryotic phylotypes or species based on 16S rRNA gene sequences (Venter et al. 2004)

• Up to 7000 viral types have been detected using a metagenomics (community genomics) approach and it is believed that viruses represent the largest unknown sequence space (Breitbart et al. 2002)

Wednesday, August 15, 2012

Page 25: Bioweek talk 2012

PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE

BIOSPHERE

Wednesday, August 15, 2012

Page 26: Bioweek talk 2012

PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE

BIOSPHERE

• They invented photosynthesis long before eukaryotes evolved

Wednesday, August 15, 2012

Page 27: Bioweek talk 2012

PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE

BIOSPHERE

• They invented photosynthesis long before eukaryotes evolved

• Their oxygen production changed the atmosphere to the oxygenic status we are currently experiencing

Wednesday, August 15, 2012

Page 28: Bioweek talk 2012

PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE

BIOSPHERE

• They invented photosynthesis long before eukaryotes evolved

• Their oxygen production changed the atmosphere to the oxygenic status we are currently experiencing

• Microorganisms degrade and remineralize organic material, others produce methane, reduce sulfate to sulfide, integrate molecular nitrogen or change the forms of inorganic nitrogen

Wednesday, August 15, 2012

Page 29: Bioweek talk 2012

PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE

BIOSPHERE

• They invented photosynthesis long before eukaryotes evolved

• Their oxygen production changed the atmosphere to the oxygenic status we are currently experiencing

• Microorganisms degrade and remineralize organic material, others produce methane, reduce sulfate to sulfide, integrate molecular nitrogen or change the forms of inorganic nitrogen

• Microorganisms drive the global cycles of carbon, nitrogen, phosphorus and sulfur

Wednesday, August 15, 2012

Page 30: Bioweek talk 2012

“WITHOUT MICROORGANISMS

ALL OTHER LIFE FORMS WILL NOT

SURVIVE”

Wednesday, August 15, 2012

Page 31: Bioweek talk 2012

SO HOW DO THEY ADAPT...

• Symbiosis

• between multicellular organisms with microorganisms showed great evolutionary success (e.g. Lichens = 1500 species)

Wednesday, August 15, 2012

Page 32: Bioweek talk 2012

SO HOW DO THEY ADAPT...

• Symbiosis

• between plant roots and fungi (mycorrhiza) = reason for spread of plants in the continents

Wednesday, August 15, 2012

Page 33: Bioweek talk 2012

SO HOW DO THEY ADAPT...

• Symbiosis

• between coral host and photosynthetic dinoflagellate

• coral host obtains sugars from the algae and the interference of algae with carbon cycling enhances calcification

• reason why coral reefs one of most diverse ecosystem

Wednesday, August 15, 2012

Page 34: Bioweek talk 2012

SO HOW DO THEY ADAPT...

• Exchange of Genes (Horizontal Gene Transfer or Microbial Sex)

Wednesday, August 15, 2012

Page 35: Bioweek talk 2012

SO HOW DO THEY ADAPT...

• Exchange of Genes (Horizontal Gene Transfer or Microbial Sex)

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Page 36: Bioweek talk 2012

CONSEQUENCES OF GENE TRANSFERS

• Cohan (2001)

• gene transfer among species increases diversity

• gene exchange can help to sustain co-existence of genetically different ecotypes

• gene exchange would help protect ecotypes from extinction if the adaptive mutation can be transferred

Wednesday, August 15, 2012

Page 37: Bioweek talk 2012

BIOGEOGRAPHY OF MICROBES

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Page 38: Bioweek talk 2012

ON DISTRIBUTION• Finlay & Fenchel 1999

• “there are no distributional barriers for small free-living organisms such as microbes”

• Finlay et al. 1996

• “global species diversity is inversely related to body size”

• suggests that the shear number of protists makes global dispersal very likely by mechanisms such as hurricanes, ocean circulations, groundwater connections, damp fur, etc

Wednesday, August 15, 2012

Page 39: Bioweek talk 2012

ON EXTINCTION

• Cohan, 2001

• “the large number of microbial cells per species makes extinction unlikely, extinction is not a threat”

• works only for “free-living microbes”

Wednesday, August 15, 2012

Page 40: Bioweek talk 2012

ON ENDEMICITY

• More evidence of endemicity and biogeography is available for microorganisms associated with plants or animals

• Hosts can be considered as islands, which permit the development of endemism in prokaryotes

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Page 41: Bioweek talk 2012

EVIDENCE OF EXTINCTION

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Page 42: Bioweek talk 2012

EVIDENCES

• Local extinctions (or strong reductions in the abundance of microbial species) probably occur quite frequently, e.g. due to clearing of forests, agricultural activity or erupting volcanoes

• a multicellular organism is best regarded as an association of species — a mini-ecosystem — and many of these species exist only in this association (e.g. coral reefs destruction, microbes in Dodo or mammoth etc)

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Page 43: Bioweek talk 2012

MICROBIAL FOSSILS?

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Page 44: Bioweek talk 2012

ARE THERE FOSSILS TO GUIDE US?

• Listgarten & Loomer 2003

• Detection of microbial fossils is difficult compared to detection of plant and animal fossils

• one of the reasons for our lack of knowledge on extinction rates of microbes.

• Stromatolites (microbial reefs) were globally distributed in the Proterozoic but the abundance decreased markedly and at present there are only a few sites left

• suggests at least local extinctions in the geological past

Wednesday, August 15, 2012

Page 45: Bioweek talk 2012

ENDANGERED

• Most free-living microbes are likely not endangered, although their local distribution might vary considerably and local extinctions

• However, associated species may be ‘threatened’ in the same way as the multicellular hosts organisms

Wednesday, August 15, 2012

Page 46: Bioweek talk 2012

THE INFECTIOUS PARTICLE...

• Emiliani 1982, 1993

• Microbes may also become extinct when one partner in a predator – prey or parasite – host system loses the adaptation race

• Example: As long as the virus cannot find an alternative host, this means self-extinction

Wednesday, August 15, 2012

Page 47: Bioweek talk 2012

SO...SHOULD WE CARE ABOUT THE POTENTIAL LOSES

OF MICROBIAL SPECIES???

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Page 48: Bioweek talk 2012

RECALL...the prokaryotic DNA world constitutes a

‘global superorganism’ that shares the gene pool by

horizontal gene transfer, the microbial ‘kamasutra’

(Doolittle 1999)

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Page 49: Bioweek talk 2012

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Page 50: Bioweek talk 2012

WITHOUT THEM...CHANGES IN BIOGEOCHEMICAL

CYCLING

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Page 51: Bioweek talk 2012

WITHOUT THEM...CORAL BLEACHING

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Page 52: Bioweek talk 2012

YOUR CONTRIBUTION

TO THEIR EXTINCTION

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Page 53: Bioweek talk 2012

OUR CONTRIBUTIONS TO POSSIBLE EXTINCTION

• antimicrobials

• habitat fragmentation

• pollution and contamination of aquatic systems

• The BIGGER THREAT: Climate Change

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Page 54: Bioweek talk 2012

EXTINCTION OF MICROBES... WE SHOULD CARE!!!

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Page 55: Bioweek talk 2012

THANK YOU VERY MUCH!!!

Wednesday, August 15, 2012


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