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Environmental Microbiology

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Title: Environmental Microbiology


1
Environmental Microbiology
Talaro Chapter 26
2
  • Environmental Microbiology
  • Study of microbes in their natural habitats
  • Microbial Diversity study of the different
    types of microbes in an environment
  • Microbial Ecology
  • Studies the interactions between microbes their
    environments
  • Involving biotic abiotic components
  • Distribution
  • Abundance numbers of bacteria

3
Microbes comprise approximately half of all the
biomass on Earth
Prokaryotes exist in all of the habitats on
Earth Extreme cold Extreme heat Low O2
Extreme pressure barophiles now called
piezophiles High salt (low aw)
Prokaryotes exits in environments that are too
extreme or inhospitable for eukaryotic cells
Extremophiles!!
Limits of life on Earth are defined by the
presence of prokaryotes which tells us what to
look for when looking for life on
extraterrestrial bodies
4
The primary role of microorganisms is to serve as
catalysts of biogeochemical cycles
textbookofbacteriology.net
5
Microbial catalysts interact on a much smaller
spatial scale, but affect the biosphere over a
long period of time
  • Nanometers to micrometers
  • Bacteria on the tip of a plant root
  • Bacteria living in specialized organs of
    invertebrates
  • Geologic Time
  • Production of O2
  • Millions to billions of years

6
Microorganism have a greater metabolic
versatility than do macroorganisms
  • Photoautotrophs
  • Chemoautrophs
  • Photoheterotroph
  • Chemoheterotrophs

7
Prokaryotes do not Exist in Isolation
Plant and animals are dependent upon the actions
of prokaryotes
Archaea and Bacteria participate in mutualistic
relationships that benefit both organisms
Only a small number of bacteria are pathogenic!
And there are bacteria that are pathogens of
animals and plants
8
Examples of Mutualism
  • Sheep and cattle (ruminants) live off grass
  • Lack the digestive enzymes to break down
    cellulose
  • Bacteria in intestinal tract break down
    cellulose
  • Products of cellulose degradation are converted
    to carbon
  • sources that the ruminants can use
  • CH4 is also produced in high amounts (belching!)
  • Sugars absorbed by animal and used for energy
  • Plants unable to fix atmospheric N2
  • Symbiotic bacteria infect roots
  • Plant requires nitrogen for proteins

9
Biofilms
Antarctica glaciers Hot springs
  • Complex aggregation
  • Bacteria, archaea, protozoa, algae
  • Microbial Mat
  • Free floating organism
  • Attached organism
  • Highly structured
  • Extracellular polysaccharide
  • Protective adhesive matrix
  • Protection from the environment
  • Protection from protozoans
  • Protection from antibiotics chemicals

Antarctic Sun February 12, 2006
10
  • Grows by cell division recruitment
  • Industrial biofilms
  • Pipe corrosion
  • Ship corrosion
  • Infections
  • Dental plaque
  • Contact lenses
  • Heart valves
  • Artificial hip joints

11
  • Physiologically Integrated
  • Each group performs a specialized metabolic
    function
  • Lateral gene transfer
  • Conjugation between different species
  • Transduction between different species
  • Cell to cell communication
  • Quorum sensing

12
1. Initial attachment
4. Maturation of Biofilm Architecture
2. Production of EPS
5. Dispersion
3. Early Biofilm Architecture
13
Microbial mat Cyanobacteria purple
bacteria Lake Cadagno, Switzerland White area is
precipitated sulfur
www.microbes.org/labs.asp
14
Cyanobacterial mat in run-off from a hot springs
at Yellowstone National Park
www.mit.edu/people/janelle/homepage.html
15
Winogradsky Column
Nutrient Cycling
  • A glass column that simulates the complex
    interactions of microbial biofilms in an aqueous
    environment
  • Upper aerobic zone
  • Microaerophilic zone
  • Lower anaerobic zone

Environmental Technology Consortium at Clark
Atlanta University and Northern Arizona
University 
16
  • Algae, cyanobacteria, aerobic heterotrophs
  • CO2 H2O ? CH2O O2
  • Oxygenic photosynthesis
  • H2O is a source of electrons
  • CH2O O2 ? CO2 H2O
  • Aerobic respiration
  • H2S oxidizers
  • CO2 H2S ? CH2O S H2O
  • Anoxygenic photosynthesis
  • H2S is a source of electrons

More on anoxygenic and oxygenic photosynthesis is
few moments
17
  • Purple nonsulfur photoheterotrophs
  • May exist as photoheterotrophs, photoautotrophs
    or chemoheterotrophs
  • Freely alternate between these metabolic modes
    depending on environmental conditions
  • Degree of anaerobiosis
  • Availability and types of carbon sources
  • CO2 for autotrophic growth
  • Organic compounds for heterotrophic growth
  • Availability of light for phototrophic growth
  • The non-sulfur label was used since it was
    originally thought that these bacteria could not
    use H2S as an electron donor
  • Can use H2S in low concentrations

18
  • Purple non-sulfur bacteria
  • CH2O O2 ? CO2 H2O (Chemoheterotrophs)
  • CH2O O2 ? CO2 H2O (Photoheterotrophs)
  • CO2 H2O ? CH2O O2 (Photoautotrophs)
  • Purple Green sulfur bacteria
  • Anoxygenic photosynthesis
  • H2, H2S or So ? SO42-
  • Sulfate reducers
  • SO42- ? S2- compound (H2S or FeS)

19
(No Transcript)
20
Quorum Sensing
  • Cell-cell communication in bacteria
  • Coordinate behavior/activities between bacterial
    cells of the same species
  • Autoinducers trigger a change when cells are in
    high concentration
  • Specific receptor for the inducer
  • Extracellular concentration of autoinducer
    increases with population
  • Threshold is reached
  • The population responds with an alteration in
    gene expression
  • Bioluminescence
  • Secretion of virulence factors
  • Biofilm formation
  • Sporulation
  • Competence

21
Energy Nutrient Flow
It is likely that most of the Earth's atmospheric
oxygen was produced by bacterial cells.
 
Plant cell chloroplast and oxygenic
photosynthesis are originated in prokaryotes.
22
Photosynthesis developed ? 3 bya
23
  • Anoxygenic Photosynthesis
  • Anaerobic bacterial photosynthesis that does not
    produce O2
  • CO2 H2S ? (CH2O)n S H2O
  • H2, H2S or So or organic compounds serves as a
    source of electrons
  • Need electrons to make fix C and make ATP
  • Purple and green photosynthetic sulfur bacteria
  • Aquatic anaerobic
  • Pigments that absorb different l
  • Bacteriochlorophyll (800 - 1000 nm far red)
  • Carotenoids (400 - 550 nm)
  • Phycobilins are not present
  • Only 1 photosystem
  • Rhodobacter
  • Oxidize succinate or butyrate during CO2 fixation
  • Hypothesized to be have become an endosymbiont of
    eucaryotes
  • Mitochondrion 16S rRNA sequences

24
Cyanobacteria purple bacteria Lake Cadagno,
Switzerland
www.microbes.org/labs.asp
25
  • Start here next time

26
Cyanobacteria
Tremendous ecological importance in the C, O and
N cycles Evolutionary relationship to
plants Cyanobacteria have chlorophyll a,
carotenoids and phycobilins
Same chlorophyll a in plants and
algae Chlorophyll a absorbs light at 450 nm 650
- 750 nm Pycobilins absorb at 550 and 650 nm
27
Some cyanobacteria fix nitrogen in specialized
cells HETEROCYSTS. Provide anaerobic environment
required for nitrogenase.
28
Cyanobacteria have membranes that resemble
photosynthetic thylakoids in plant
chloroplasts. Hypothesized that cyanobacteria
were the progenitors of eucaryotic chloroplasts
via endosymbiosis. Cyanobacteria are very
similar to the chloroplasts of red algae
(Rhodophyta).
29
Several species of cyanobacteria are symbionts of
liverworts, ferns, cycads, flagellated protozoa,
and algae. The photosynthetic partners of
lichens are commonly cyanobacteria. There is
also an example of a cyanobacterium as
endosymbionts of plant cells. A cyanobacterial
endophyte (Anabaena spp.) fixes nitrogen that
becomes available to the water fern, Azolla.
www.botany.wisc.edu/.../AnabaenaAzolla2.jpg
www.csupomona.edu
30
  • Several thousand cyanobacteria species.
  • Many are symbionts.
  • 200 species are free-living, nonsymbiotic
    procaryotes.
  • Cyanobacteria often are isolated from extreme
    environments.
  • Hot springs of the Yellowstone National Park
    Antarctica lakes
  • Copious mats 2 to 4 cm thick in water beneath
    more than 5 m of permanent ice.
  • Cyanobacteria are not found in acidic waters
    where algae (euckaryotic) predominate.

www.resa.net/nasa/antarctica.htm
31
Green alga
Figure 17. The distribution of photosynthetic
pigments among photosynthetic microorganisms.
Red alga
cyanobacterium
Green bacterium
Purple bacterium
textbookofbacteriology.net
32
Anoxygenic bacterial photosynthesis Photosystem
I Cyclic Photophosphorylation Cyanobacteria,
algae and plants, also have Photosystem II
iron sulfur protein
ATP is generated during photophosphorylation
bacterial chlorophyll
cyclic photophosphorylation
33
Anoxygenic bacterial photosynthesis Photosystem
I
Electrons from H2S are passed to ferredoxin NADP
is reduced
Autotrophic CO2 fixation CO2 ? (CH2O)n
CO2 H2S ? (CH2O)n S H2O Oxidation of H2S is
linked to PS1
textbookofbacteriology.net
34
Anoxygenic photosynthesis
  • Limitations on the amount of C that can be fixed
  • Need more electrons to fix more C

35
Oxygenic Photosynthesis Plants, algae and
cyanobacteria
Electrons lost here must be replenished
PS2 ensures a constant supply of electrons
ATP is generate by noncyclic photophosphorylation
CO2 ? (CH2O)n Calvin Cycle
Electrons from PS1 reduce ferredoxin Ferredoxin
passes the electrons to NADP
H2O is source of electrons
textbookofbacteriology.net
36
Table 6. Differences between plant and bacterial
photosynthesis
textbookofbacteriology.net
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