2. Deepwater Horizon rig explosion, April 2010
Other major spills - many much larger - Gulf War II (1991)
Gulf of Mexico (1979)
Caribbean (1979) Central Asia (1992)
Gulf War I (1983)
Angola (1991)
S Africa (1983)
Brittany France (1978)
PHYSICAL CLEAN - UP METHODS:
booms, skimmers, & absorbents in open water
pressure washing, rakes & bulldozers on shorelines
CHEMICAL CLEAN - UP METHODS
dispersants - act like a soap to break up oil
gels - react with oil to form solid
FOCUS OF THIS UNIT - BIOLOGICAL METHODS...

3. BENZENE, A KNOWN CARCINOGEN, IS VERY STABLE/LONG-LASTING IN THE ENVIRONMENT
IT IS ALSO A COMMON BY-PRODUCT OF THE OIL EXPLORATION PROCESSES (NOT SPILLS)
IT CAN BE DIGESTED BY A SALT-TOLERANT BACTERIUM, Marinobacter

4. BIOREMEDIATION by Pseudomonas bacteria, in a specific mixture:

5. OF MERCURY - the bad and the good of microbes...
BIOREMEDIATION
OF MERCURY - the bad and the good
of microbes...
First, Desulfovibrio bacteria adds a methyl group to the dumped mercury, which makes the mercury much more likely to attach to plankton, which are eaten by fish
Then, Pseudomonas bacteria convert the methyl mercury to (relatively) harmless elemental form of Hg

6. BIOFILMS - revisiting “emergent properties” - their success depends upon:
and the properties that emerge are…
COMPLEX ARCHITECTURE
QUORUM SENSING
ANTIMICROBIAL RESISTANCE

7. So, where are these biofilms found? everywhere!
your mouth - dental plaque
desert rocks - “varnish” - what is carved away in petroglyphs
ponds, shorelines, oceans...Mars???

8. Quorum Sensing and EPS (Extracellular Polymeric Substances)
Green Fluorescent Protein is used to tag the gene expression of an EPS in conditions (a) favoring and (b) inhibiting quorum sensing

9. How do bacteria “communicate” in QS?

10. Initial colonizers of a Staphylococcus aureus biofilm on the fibers of a medical gauze dressing.
Model of biofilm resistance to antibiotics.
Initially the antibiotic kills some biofilm cells (white). The immune system should kill persisters (pink). After the antibiotic treat- ment is reduced, any persisters repopulate the biofilm. (Nature Reviews 5: 48-56)

11. Nice animation showing the development of a biofilm in the context of a joint replacement recovery. Don’t be daunted by the references to the immune system specifics - cytokines etc...just pull out the stages that the bacterial population goes through to become a biofilm.

12. BIOFILMS & TRICKLE FILTER BEDS...
trickle filter system at a sewage plant

14. Fighting bacteria with viruses - bacteriophage T4
view the animation of the T4 life cycle below.
Such bacteriophage have been employed for use in
disinfection of waste water.

15. Nitrogen levels reduced 95%
Results:
Nitrogen levels reduced 95%
Phosphate levels
reduced 40%
Oxygen levels
increased 60 fold
Rafts of floating islands of plants and their biofilms are being used to reduce the levels of pollutants in small bodies of water such as the one shown here.