Lecture 2: Historical Roots of Microbial Ecology

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Lecture 2 Historical Roots of Microbial Ecology
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What is Microbial Ecology? What is
Microbial? What is Ecology?
of or referring to a minute life form a
microorganism, especially a bacterium that
causes disease. Not in technical use.
the study of the interactions between organisms
and their environment
Microbial ecology The study of interactions
between microorganisms and their environment
(chemical, physical, and biological environment!)
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• The term microbial ecology really wasnt in
  common
• use until the late 1960s
• Why?
• Microbial ecology has its roots in microbiology,
  rather than ecology
• The history of the field is largely a transition
  from laboratory pure cultures to studying
  organisms in nature

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"Imagination should give wings to our thoughts
but we always need decisive experimental proof,
and when the moment comes to draw conclusions and
to interpret the gathered observations,
imagination must be checked and documented by the
factual results of the experiment."
basic vs. applied science fermentation
biological process carried out by microorganisms.
Germ theory foundation of brewing of beer,
wine-making, and pasteurization. nature of
contagious diseases potato blight, silkworm
diseases, and anthrax. immunization Public
experiments!
Louis Pasteur (1822-1895)
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Robert Koch (1843-1910)
- discovered the Bacillus strains that cause
cholera and anthrax - agar media for pure
cultures (earlier had tried sliced boiled
potatoes!) - pure culture paradigm isolate an
organism and see what it does
disease and medical microbiology pure culture
paradigm
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Pure Culture Paradigm
extremely important conceptual development in
microbiology (and in microbial ecology,
too) remove organisms from complex
communities isolate key processes obtain
reproducible results This method is still used
today Attitude of Kochs time Work with impure
cultures yields nothing but nonsense
and Penicillium glaucum (Oscar Brefield 1881)
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Sir Alexander Fleming (1929), examining exactly
such an impure culture (Staphylococcus culture
contaminated by Penicillium), led to the
discovery of penicillin.
Agar petri dish Staphylococcus
colonies Penicillium contaminant
zone of no bacterial growth, due to penicillin
produced by fungus
Interference competition! classic ecological
process
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Sergei Winogradsky (1856-1953)

• - isolated nitrifying bacteria
• winogradsky column microbial communities
  develop along a gradient of oxygen tension
  method still used today
• - described oxidation of hydrogen sulfide,
  sulfur, ferrous iron
• - all leading to the concept of chemoautotrophy
  deriving energy from chemical oxidation of
  inorganic compounds and carbon from CO2

Bacteria central in element transformations Found
er of soil microbiology
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Martinus Beijerinck (1851-1931)
The way I approach microbiology...can be
concisely stated as the study of microbial
ecology, i.e., of the relation between
environmental conditions and the special forms of
life corresponding to them
Founder of the Dutch Delft School Of Microbiology
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Martinus Beijerinck (1851-1931)

• - a man of science does not marry
• isolated N fixers and S reducers
• microbial ubiquity all microorganisms are
  everywhere conditions and resources determine
  who flourishes
• enrichment culture growth medium tailored to
  suit particular metabolic function
• with Winogradsky, recognized that microbes are
  the major players in element transformations
• led to field of global biogeochemistry

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Albert Jan Kluyver (1888-1956)

• student of Beijerinck
• microbial physiology
• comparative approach
• unifying metabolic featuresamong microbes
• leader of the Dutch school after Beijerinck

microbial physiology comparative approach
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Cornelius Bernardus van Niel (1897-1985)

• -entered army at age 18, discouraged by
  impersonal life
• in military, read Zola, France, Ibsen, Shaw,
  Nietzsche majorlater influence on his teaching
• -Kluyvers lecture inspired himto study
  microbiology
• -student of Kluyver, third in theDutch Delft
  School
• Isolated purple sulfur bacteria

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Kees van Neil

• moved to US in 1928, bringing the Delft school
  tradition with him
• Nover intended to immigrate didnt like US
  materialism
• But he was immediately taken with Carmels charm,
  stayed for the rest of his life (even turning
  down Kluyvers chair!)
• worked at Hopkins Marine Station, focusing on
  purple and green bacteria
• Major contribution, chemistry of photosynthesis
• 2 H2A CO2 CH2O 2 A H2O
• where A can be S or O
• extended model to photosynthesis in green plants
• oxygen from water, not from CO2
• Also, chemistry of denitrification, definition of
  prokaryote in 1961 (with R. Stanier)

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Kees van Neil

• taught famous lab course focusing on studying
  microbes from nature(first course in microbial
  ecology?)
• Lecture experiments
• Excellent facultystudent ratio
• Philosophy of hypothesis testing, falsification
  moving from clearly erroneous to more correct,
  but never immutable conclusions

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Robert E. Hungate (1908-2004)
-student of van Niel -methods for isolating
anaerobes -culture methods select using
natural substrates, rather than guesses about
what organisms eat -microbiology of guts of
rumen, termites -ASM president when
EnvironmentalMicrobiology and Microbial
Ecology formally recognized
AKA Grampa Bob Anaerobic methodsCows and
termites
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1960s Ronald Atlas, Richard Bartha - studies
of petroleum degradation - led to new field of
bioremediation, - extended to many other
pollutants DDT, PCBs, mercury, selenium,
industrial solvents   1970s fuel-shortage -
shortage in N fertilizer - sparked interest in
the biology of nitrogen fixers    
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Current trends in microbial ecology a. space
exploration microbes in extreme environments
(hot springs, thermal vents, lithosphere) b.
molecular techniques diversity of
microorganisms (Carl Woese), new methods to
assess presence/abundance of individual species
in situ c. realization that with pure
culture/enrichment techniques, we know somewhere
between 1-10 of existing microbial species
lots to learn! d. biology of climate change,
global biogeochemistry Next time, Bacteria and
Earth History. Read Chung and Bryant 1997 and
Schopf 1992, for discussion.