3. A structured community
of bacterial cells
Enclosed in a self-produced
extracellular polymeric
substance(EPS)
Structure EPS Surface
Adherent to an inert or
living surface
Biofilms
7. Detachment Environmental Biotechnology
● Abrasion
-Direct physical contact with biofilm structure
● Erosion
-shear forces exerted on the biofilm
● Sloughing
-Result of chemical changes
-Regulated by the biofilm community
● Enzymatic EPS degradation
12. Biofilms – The social life of microorganism
More than 99 % of all microorganisms on earth
prefer to live in biofilms
WHY ?
!
7 secrets of the Good Life in Biofilms
13. Secret #1: EPS-The House of Biofilms Cells
● What is EPS?
-A high-molecular-weight polymer that is composed of
polysaccharides, proteins, nucleic acids, lipids and other
biological macromolecules
-Secreted by a micro-organism into the surrounding
environment
!
!
● What does EPS do?
-Envelops cells and helps
the aggregates adhere to
surfaces
14. What does EPS keep together?
Environmental Biotechnology
Weak Interactions
15. ● 50% or more of void in biofilm volume
!
●Flux of oxygen into the biofilm is not simply planar
-Flux from void spaces
-Flux from channels
!
●Oxygen can penetrate to substratum
!
●No oxygen found inside dense cell aggregates
!
●Heterogeneity of oxygen distribution causes heterogeneous growth
Secret #2 Oxygen Gradients Environmental Biotechnology
Water
channels
Substratum
16. Secret #3 Microconsortia
!
● Methane-oxidizing cell aggregates from
marine sediments. The aggregates contain
methanogenic bacteria (red) surrounded
by sulfate-reducing bacteria (green).
!
● Possible mechanism for syntrophic
anoxic methane oxidation in the cell
aggregates.
Environmental Biotechnology
17. Secret #4 Resistant to Antimicrobial Compounds
1. Slow growers are spared the effects of antibiotic drugs which is effective
against fast-growing cells.
2. Intracellular signals can alter the physiology of the biofilm.
3. Negatively charged biofilm binds to positively charged antimicrobials.
4. Persister cells do not grow or die in the presence of an antibiotic.
5. Population diversity – improve the chance to survive anyhow
19. Secret #6 Density dependent communicationEnvironmental Biotechnology
● First observed in Vibrio fischeri
●Bioluminescence :
-Only happens when - population density reaches a certain level.
-Brighter during the nighttime
-Protection against –
:Ultraviolet radiation damage to genes of V.fischeri
:The pathogenicity of bioluminescent V. fischeri
Euprymna scolopes– Host of V.fischeri
V.fischeri
Formation of biofilm is needed to develop the symbiotic relationship
20. Secret #7 Sex (as horizontal gene transfer)
● High cell density in biofilms
!
● Gene exchange facilitated
Environmental Biotechnology
male
female
Sex pilus
21. Advantages of “the Biofilm Mode of Life”
Environmental Biotechnology
●Provide defense
-Physical forces
-Phagocytosis
-Penetration of antimicrobials
!
●Provide favorable microniche
-Can attach to nutrient rich surfaces
-Can attach to surface in flowing systems
-Fixes the bacterial cells where the nutrients
are either abundant or often replenished
!
●Allow microbes to live in close proximity
-Facilitates communication and cooperation
-Can result in genetic exchange
!
●Nature’s default
-Best mode of growth in the “real world”
Cellular process of engulfing
solid particles by the cell
membrane for the acquisition of
nutrients
22. How is a Biofilm like a CITY?
Careful selection of locationLimited settlement of too many
microorganism
Storage of energy (EPS)
Intracellular communication
(Quorum Sensing)
Transfer of information
(genetic transfer)
Emigration when population gets
Too large for resources
Biofilm
City
25. Beneficial Biofilms
● Many play an important role in the ecology of the earth and the sustainability
of life in general.
- The report, "Global Environmental Change”:. Microbes have major roles in the
recycling of elements vital to life."
!
- We are learning, those microbes often live in biofilm colonies on surfaces.
Bioremediation
Water
treatment
Microbial
Fuel Cell
Microbial
Leaching
27. Bioremediation
● Soil Biofilms
- Continuous surface films (5-15 um in thickness)
- Variety of aggregate films (5-30 um in diameter)
- EPS, extracellular polymeric substances, which protrude from the surface film
and form bridges to adjacent sand grains
Confocal micrograph of biofilm on sand particles
28. ● Biofilm enhances bioavailability
-Polynuclear Aromatic Hydrocarbons (PAHs):
two or more fused benzene rings
Hydrophobic and low bioavailable
- Strategies to promote bioavailability
EPS
Biofilm production
Bioremediation
29. ● Bioavailability Enhancement
- Some EPS (e.g., sphingan): effective at taking up PAHs
!
: PAHs taken up by these polysaccharides are bioavailable
!
: EPS acts to temporarily store pollutants for use during periods of
nutrient deficiency
!
: During periods of high nutrient delivery, bacteria may utilize
available nutrients and collect hydrophobic contaminants for later
use
Bioremediation
31. Water Treatment
- Oldest design
- 1-4” rocks, variety of plastic packing materials
Water flows as thin film over rocks, most of area is void space open to air. Detached
biofilm settles out, is dewatered and disposed of.
● Trickling filter
● Biological tower
- Plastic media, not rocks (lighter)
- Higher Surface Area
- Smaller land area
32. Water Treatment
• Attached growth system
• Design based on
specific surface area
• Aeration by rotating disks
• Lower organic loading,
Longer detention time
Little short-circuiting
! better performance
33. Water Treatment
● Fluidized Bed
- Attached growth system
!
- Media (sand, activated
carbon) fluidized in reactor
!
- Requires relatively small
space and simple to operate
!
- Used for denitrification
34. ● Nitrification/Denitrification
- Nitrification
: Oxidation of ammonia (NH4
+) to nitrate (NO3
-) via nitrite
(NO2
-)
: Nitrosomonas; 2NH4
+ + 3O2 ! 2NO2
- + 4H+ + 2H2O
: Nitrobacter; 2NO2
- + O2 ! 2NO3
-
!
- Denitrification
: Bacillus, Pseudomonas; nitrate (NO3
-) to nitrogen gas
(N2)
Water Treatment
35. Traditionally…
Membranes can serve purpose of clarifier!
Can get rid of these… …by installing these
Membrane BioReactor (MBR) consists of an activated sludge reactor and a micro/ultrafiltration membrane.
36. Biofilms and Membranes
1BNR (Biological Nutrient Removal): advanced treatment of nitrogen and
phosphorus
1Membrane unit: physical barrier for separation between
water and microorganisms
3Membrane Bio-Reactor (MBR) = The SYNERGY effect
!
* Increase; MLSS concentration and contact time
* Decrease; sludge production
* E.coli free effluent ! offering the possibility of water reuse
* Compact process (50% of CASP : classic activated sludge process)
+
=
From prof. Shin’s Lab
38. ● The extraction process, when done with chemicals, is
called "leaching."
Microbial Leaching
- Leaching : is commercially used for the extraction of Cu, Pb, Zn, and Ur
from sulfide-containing ores
- Thiobacillus thiooxidans and Thiobacillus ferrooxidans are acidophilic and
generally found in acid environments e.g. hot springs and sulfide ore
deposits
- they obtain carbon from CO2 and energy for growth from the oxidation of
either iron or sulfur
39. - low grade Cu ores contain <0.5% Cu in the form of covellite (CuS)
8 Fe2+ + 2 O2 +8 H+ 8 Fe3+ + 4 H2O
CuS + 8 Fe3+ + 4 H2O Cu2++ 8 Fe2++ SO4
2-+ 8 H+
T. ferrooxidans
● Microbial leaching in Copper mining
Microbial Leaching
Thiobacillus ferrooxidans
41. ● Dump leaching
Microbial Leaching (Technical Application)
- Most commonly applied method
- Very slow process (3-10% of the copper content leached out per year_20 years in complete)
- Simple, cheap, little labor
- 2.0-3.5 of pH is circulating by liquor
- Thiobacillus ferrooxidans need only inorganic nutrient taken from ore
- 20-25% of total copper production in USA, 5% in the whole world by bio leaching
42. ● In situ leaching
Microbial Leaching (Technical Application)
- Difficult if the ore body is impermeable
- These leaching were done abiotic without
using bacteria
In Canadian uranium mines
48. In natural environments
● Biofilms grow virtually everywhere
● Moisture
● Nutrients
● Surface
!
!
● Producing toxic alga blooms
● Creating oxygen depletion zones in lakes, rivers and coastal environments
● Mobilize toxic elements
Green algae form at surface of river.
49. Mobilizing toxic elements
➢Nature (2004)
■ A pink biofilm was found growing hundreds of feet
underground
■ The pink biofilm
■ bacteria and fungi that grow on surfaces.
■ contain acidic solution-laden with dissolved iron, copper, zinc
and arsenic-emanating
Environmental Biotechnology
➢How??
▪Formation of biofilm
▪Hazardous metals trap in it
▪Energy source
!
50. In industrial environments
Waste water treatmentMarine Biofilms
Water distribution
Filtration Application
Water cooling
distribution
Biofilms
51. Membrane fouling (Biofouling)
Definition : Biofouling refers to undesirable accumulation of
biotic deposit on surface (membrane)
Membrane filtration process
Adapted from Ivnitsky et al. 2005.
Desalination 185: 255-268.
52. Membrane fouling mechanisms
●External fouling
Hydraulic permeability and solute transmission characteristics
are altered due to:
❑Increase in the effective membrane thickness
❑Blockage of pore entrance
❑Constriction of pore entrance
53. Environmental Biotechnology
Membrane fouling mechanisms
●Internal fouling
Hydraulic permeability and solute transmission
characteristics are altered due to:
❑Internal blockage of pore
❑Internal constriction of pore
❑Alteration of pore tortuosity
!
58. ● Affect turbidity, taste, and odor
● Red (iron) and black (manganese) in H2O
● Increased frictional resistance
● Pipe corrosion
● Failure to meet water quality criteria
Effect of biofilm in pipeline water distribution
59. Water cooling
distribution
Biofilms in cooling
water systems are
known to reduce
heat transfer
!
Legionella is still a
problem in cooling
towers.
!
Biofilms can
cause clogging in
filters and pipes.
!
!
!
Piling
Offshore platforms,
ship hull
Others
!
In shipping industry
• Biofilm coating the hull
• Effect efficiency of the
vessel
!
!
Marine StructuresWater Filtration
61. Human Health
●Control of biofilms is a major concern
➢ Health
➢ Economic
●Biofilms cause for contaminations of medical devices
➢ Nosocomial infections
62. Human Health - lung infectionEnvironmental Biotechnology
Single microbes attach
in alveoli
Biofilm start to forms
Biofilm become thicker
(matured)
65. Solution
● Several methods to control biofilms
➢Mechanical approach : ultrasonic energy
➢Combination approach : ultrasonic with antibiotics
!
●More effective methods are greatly needed !!
Environmental Biotechnology
66. Environmental Biotechnology
!
There is a good side and bad sites of biofilms…so our
job to utilize and control them
!
Thank you for listening
Save our environments and earth..
PEACE!!!!
