Announcements:
 
 
Today’s Plan:
 
 
 
 More 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
2. What’s it like in the wild?
a. Characteristics
b. How do microbes make it?
Nutrient capture, shape, biofilms
3. Degradation of Synthetic Chemicals
  a. Bioremediation - use of microbes to detoxify or degrade pollutants
  i. Intrinsic, enhanced
  a) fertilizing
b) bioaugmentation
  b. The Exxon Valdez
 

 

Microbial life in the ‘wild’
Competition
How many organisms in 1 gram of moist  soil?
About the same number as the world’s population (109)
•Competition is stiff!
•Limited nutrients
•Limited space
•

Skin lab will demonstrate how competition will limit growth of certain bacteria

How do pathogens invade?
Open wounds!
Opportunism!
•

Bacteria have been around since the beginning of life

•Evolution allows survival
•Rapid evolution due to lateral gene transfer and rapid reproduction, recombination and frequency of mutations
•

Bacterial “weapons” 

•Offensive weapons = Antibiotics
•Defensive weapons = Plasmids  
–R-factors transfer of resistance to antibiotics to others
 

Resistance

Non-resistant are killed
Resistant cells survive
Genetic exchange
Antibiotic no longer effective
•

Quorum Sensing – inducible genes are turned on, transcribed and translated

Triggered by surrounding cell density,
environmental changes, by-products,
proteins, pheromones, etc.

"Cell to cell communication"

Biofilm formation
What is a b

iofilm?

Industrial Biofilms
Voice prosthesis biofilm
Biofilms on teeth
Dental plaque stained by neutral red on an original tooth surface on a human volunteer after nine days of no oral hygiene. Reason why physical means of removal (brushing) is necessary versus chemical only (disinfecting mouthwash).
 

Contact lens case biofilm

 

Wastewater Treatment!

Trickling Filters
 

Biofilm resistance

Biofilm treated with chloramine disinfectant.
Red = actively respiring cells, Green = non-respiring
Non-respiring  (green) cells are less
susceptible to treatment
 
Bioremediation
Use of microbes to detoxify or degrade pollutants
 

Emulsification- small droplets give greater surface

 

Intrinsic biodegradation
Natural attenuation - allowing natural processes act on contaminants to reduce them to acceptable levels.
Advantages:
Cheap
Less intrusive/disruptive

Disadvantages:
Hard to prove it’s occurring

Slow
Doesn’t always work
 

Leaking Underground Storage Tanks (LUST)

About half of all gasoline storage tanks are believed to be leaking.
Hard to tell if bioremediation is occurring or simply dilution.
 

Treatment options

Excavation- Take soil for better conditions for degradation

Soil Vapor Extraction collect vapors pumping air increases degradation
Fertilization will promote growth of degrading organisms
Bioaugmentation adding degrading organisms
Bioremediation formulations
 

True or false?

Microorganisms that are potential pathogens can not be introduced into the environment.

False