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Today’s Plan:
Start Environmental Microbiology.
 
Unit 4- Role of Microbes in Health, Disease and Environment
 
A. Environmental Microbiology – applications of microbial interactions
1. Community Interactions
a. Populations, communities
b. Producers, decomposers, consumers
c. Interactions
Symbiosis, commensalism, mutualism, parasitism
d. Biogeochemical cycling
C-cycle, N-cycle

 

 
Environmental Microbiology

 

Environmental Microbiology deals with microbial processes and the interaction of microbes with each other and with the environment
Microbes are ubiquitous!
 

If you were to chose one role or niche for bacteria in the environment, what would if be?

DECOMPOSERS!
 

They keep “cycles” moving

 

Arsenic-rich thermal mat

Populations Groups of one species
Community Groups of populations
Ecosystem Biotic and abiotic factors
 

Microbial roles

Photoautotrophs- Algae
Decomposers- Bacteria and Fungi
Consumers- Protists
 

Symbiosis - living together

 

Commensalism

Nutrient broth incubated aerobically with:
Pseudomonas aeruginosa
+
Clostridium sporogenes
 
Feed together but
different “niches”
 

Mutualism

Both organisms benefit
 
Lichen = fungus and alga
(or cyanobacterium
Fungus- Chemoheterotroph (right?)
Cyano/alga- Photoautotroph
What does each provide?
    Fungus- provides water and nutrients to alga
    Cyano/alga- Provides carbon (sugars) to fungus
 
Fungal cortex protects
the algal layer
Fungal medulla attaches
to the substrate
 
Parasitism
One organism benefits and
harms the host organism
 
What makes an effective parasite?
Not killing your host
is a good idea!
 
d. Biogeochemical Cycles
Microbes play an important role in the cycling of major elements in Nature, Carbon, Nitrogen, Sulfur, and Phosphorus.
 

We will just look at Carbon and Nitrogen

 

The Carbon Cycle

The global carbon reservoirs:
 
Atmosphere
•Land
•Aquatic environments
 

Fig. 27.3

 

Processes:

C-fixation - inorganic C to organic C
Respiration - organic C to inorganic C (w/ O2)
Fermentation - organic C to inorganic C (w/o O2)
Methanogenesis - CH4 production
Methane oxidation - CH4 consumption
 

The Nitrogen Cycle

•N exists in a number of oxidation states
•N is needed for proteins, nucleic acids and other compounds
•N2 constitutes about 80% of the Earth’s atm
•Eukaryotes can not use N2
•Nitrate NO3- is the form usable by plants
•
•What information do we need to understand the Nitrogen cycle?
 

Energy Transferred

•Oxidation
–electron lost (hydrogen)
–energy released
•Reduction
–electron gained (hydrogen)
–energy bound
 
Fig.27.4

 

Denitrifiers

BacillusPseudomonas

NO3- --> NO2-, NO, N2O or N2
 

Processes:

Denitrification - NO3- to N2 gas
N fixation - N2 gas to NH3
N mineralization (ammonification) - Organic N to NH4+ 
Nitrification - NH4+ to NO2- and NO3-

Is fixation anabolic or catabolic?

Is energy used or released?
Where are the electrons? Bound!
With the hydrogens in ammonia

 

Is nitrification and ammonification anabolic or catabolic?
Is energy used or released?
Where are the electrons? Generating ATP
 

SEM of microbes on a sponge

 
Most of the previously mentioned
interactions are occurring