Environmental Microbiology. Talaro Chapter 26. 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
Prokaryotes exist in all of the habitats on Earth
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
Nanometers to micrometers
Bacteria on the tip of a plant root
Bacteria living in specialized organs of invertebrates
Production of O2
Millions to billions of years
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
Antarctic Sun February 12, 2006
4. Maturation of Biofilm Architecture
2. Production of EPS
3. Early Biofilm Architecture
Cyanobacteria & purple bacteria
Lake Cadagno, Switzerland
White area is precipitated sulfur
a hot springs at Yellowstone National Park
More on anoxygenic and oxygenic photosynthesis is few moments
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.
Lake Cadagno, Switzerland
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
Some cyanobacteria fix nitrogen in specialized cellsHETEROCYSTS.
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).
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.
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.
Figure 17. The distribution of photosynthetic pigments among photosynthetic microorganisms.
Cyanobacteria, algae and plants, also have Photosystem II
iron sulfur protein
ATP is generated during photophosphorylation
Electrons from H2S are passed to ferredoxin
NADP is reduced
Autotrophic CO2 fixation
CO2 + H2S (CH2O)n + S + H2O
Oxidation of H2S is linked to PS1
Limitations on the amount of C that can be fixed
Need more electrons to fix more C
Plants, algae and cyanobacteria
Electrons lost here must be replenished
PS2 ensures a constant supply of electrons
ATP is generate by noncyclic photophosphorylation
Electrons from PS1 reduce ferredoxin Ferredoxin passes the electrons to NADP
H2O is source of electrons
Table 6. Differences between plant and bacterial photosynthesis