Microbial Nutrition and Ecology
Chapters 6 & Chapter 25
Some topics also covered in lab:
-- O2 requirements
-- culture media and conditions
In Chapter 25…
You are not responsible for
-- food preservation will be covered later
-- water quality testing is also covered in lab
Understand purposes of 1O & 2O wastewater treatment.
Prevention of food spoilage will be covered later in the semester
Hmmm…? Biological warfare is under “applied microbiology”! Read for
general enlightenment
Microbial Ecology
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Numbers of bacteria
From Naturalist, by E.O Wilson
“If I could do it all over again, and relive my
vision in the twenty-first century, I would be a
microbial ecologist. Ten billion bacteria live in
a gram of ordinary soil, a mere pinch held
between thumb and forefinger. They represent
thousands of species, almost none of which are
known to science. Into that world I would go
with the aid of modern microscopy and
molecular analysis. I would …travel in an
imagined submarine through drops of water
proportionately the size of lakes, and track
predators and prey in order to discover new
life ways and alien food webs. All this, and I
need venture no farther than ten paces outside
my laboratory building. (p 364)
Some Recent Estimates of Bacteria
On humans:
1014 / human
On leaves:
1011 / meter2
In oceans:
1029 cells
In soils:
1029 cells
In Earth’s crust:
1030 cells
1012 = 1 trillion
Total carbon allocation: (~ ½ that of plants)
Microbial Ecology
Whitman et al, (1998) PNAS 95:6578
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How does growth in nature differ from growth in the lab?
Inter-species interactions
Microhabitats prevail
“Feast or famine”
Biofilms
Biofilms
Biofilm on plant surface
Quorum sensing
Cell Density
Biofilms
Virulence
Engineered GFP QS
Danino et al(2010) Nature 463, 326-330 (Supplementary Movie 5)
http://www.nature.com/nature/journal/v463/n7279/full/nature08753.html
Microbial Ecology
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What are the different modes of Microbial Nutrition?
All organisms have
three fundamental requirements
Carbon
Energy
Mineral nutrients
Bacterial Growth and Metabolism
4
Prokaryotes are much more varied in their sources
of C and energy
Bacterial autotrophs
Phototrophs
-- photosynthetic bacteria
Chemoautotrophs
“Lithotrophs”
-- mineral oxidizing bacteria
Bacterial Growth and Metabolism
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Bacterial heterotrophs
Photoheterotrophs
Chemoheterotrophs
saprophytic
parasitic
Generalists vs
fastidious bacteria
Bacterial Growth and Metabolism
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Chemoheterotrophic Metabolism
Overview of Cellular Respiration
Stages of cellular respiration
** Review on your own**
Aerobic vs anaerobic metabolism
Where does chemiosmotic ATP synthesis
occur in prokaryotes?
-- no mitochondria!
Bacterial Growth and Metabolism
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Fastidious bacteria often have
metabolic deficiencies
Auxotrophic bacteria
-- need specific
organic nutrient(s)
Some bacteria are said to be
‘Metabolically defective’
Rocky Mountain Spotted fever
-- often obligate intracellular pathogens
Chlamydia trachomatis (Chlamydia)
-- cannot produce ATP
Ricketsia ricksii (Rickettsia)
-- very fastidious; cofactors,
-- does not produce pyruvate
Bacterial Growth and Metabolism
Rocky Mountain
wood tick
8
Chlamydia
Chlamydia trachomatis
-- metabolically defective
nongonorrheal urethritis
Most common STD in US
3-5 million
often undiagnosed
Complex life cycle
-- elementary bodies (0.3 μm)
-- reticulate body (~ 0.8 μm)
causes Trachoma
-- blindness
Pathology
9
Bacterial O2 requirements
vary widely (covered in lab)
Obligate aerobes
Facultative aerobes
Microaerophiles
Obligate anaerobes
-- cannot grow in presence of O2
-- why?
Aerotolerant anaerobes
-- can grow with O2 but do not use it
-- why?
Some Anaerobes can use
other terminal e- acceptors
-- diminishes ATP yield
Bacterial Growth and Metabolism
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Fermentation
Functions
End products
End products important for
-- bacterial identification
-- food and chemical industries
Bacterial Growth and Metabolism
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Beer production
Normal beer: only yeast
… boring!
Lambic beer … yeast and bacteria!
Yeast CO2 production
Bacterial Growth and Metabolism
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Cheese production
Involves bacteria (and sometimes fungi)
Curdling stage
Ripening stage
Bacterial Growth and Metabolism
13
Autotrophic bacteria
CO2 is carbon source
Energy from light (phototrophs)
or inorganics (chemoautotrophs)
Phototrophs
Purple sulfur bacteria
-- anoxygenic Ps
Cyanobacteria
-- oxygenic Ps
We will discuss Chemoautotrophs
under ecology
Bacterial Growth and Metabolism
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Cyanobacteria
“blue-green” pigmentation
Visit NASA’a
“Stromatolite
Explorer” on-line
Habitat
Stromatolites
Oxygenic photosynthesis
Bacterial Growth and Metabolism
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Purple sulfur bacteria
Anoxygenic Photosynthesis
Habitat
Pigmentation
Sulfur granules
Bacterial Growth and Metabolism
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Chemoautotrophic bacteria
CO2 is source of carbon
inorganic minerals are energy source
Groups we will examine:
Nitrifying bacteria
Iron bacteria
Sulfur bacteria
Chemoautotrophs ‘oxidize’ their energy sources
i.e., electrons removed
Play important ecological roles
Microbial Ecology
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Iron-oxidizing Chemoautotrophs
Thiobacillus ferrooxidans
need ferric (Fe2+) iron
obligate acidophiles
acid mine drainage
Microbial Ecology
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Biohydrometalurgy of copper
Employs chemoautrophs
low grade ore, tailings (< 0.4% Cu)
Environmental issues
Microbial Ecology
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Bacteria and Biogeochemical Cycles
Preparation of an aquarium
N cycling in aquatic ecosystems
The Nitrogen Cycle
Nitrification
N Assimilation
Decomposition & Excretion
Denitrificatiion (anaerobes)
N fixation
Nitrogen Cycle
Microbial Ecology
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Nitrogen-fixing bacteria
Rhizobium
Symbionts with legumes
Azotobacter
Soil inhabitants
Microbial Ecology
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Sulfur cycle
-- demonstrated in a Winogradsky column
Sergius Winogradsky (1856-1953)
Martinus Beijerinck (1851-1931)
Important roles of
Sulfur assimilation
-- all organisms assimilate S into protein
Chemoautotrophs
-- extract e- from reduced S (H2S, S2)
Photoautotrophs
-- H2S is e- source
Heterotrophic anaerobes
-- SO4 is alternative O2 acceptor
Microbial Ecology
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Endosymbiosis in Riftia
Sulfur-oxidizing chemoautotrophs
Hydrothermal vents
Thermal vent
Vent Community
Microbial Ecology
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Symbiosis between bacteria and animals is very common
Humans
Ruminants (cows, sheep, deer,
giraffes, goats, etc)
- Rumen
- Bacterial fermentation
- Acid production
The incredible hoatzin
(pronounced ‘what-seen’)
National bird of Guyana
Fistulated cow
Microbial Ecology
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