biofilm

1. Biofilm - Basics & Recent
Concepts
Dr.Sheeja S.Varghese
Saveetha Dental College

2. History
• Dates back to 1684
when Van Leewenhoek
identified the bacteria
(animicules) from dental
plaque (scruf)

3. Important turn
• Mid 1800 – Robert koch
developed nutrient
medium for growth and
isolation of microbes.
• Concentrated on
planktonic growth

4. 20th century
• Henrici(1933) & Heukelekian and
A.Heller(1940) reported the growth of
microbes on surface.
• 1940 - Claude ZoBell described fundamental
characteristics of attached microbial
community
• Harremoes (1977) used the term biofilm

5. What is Biofilm?
• A matrix enclosed bacterial population
adherent to each other and or to surface or
interface.
• Ecological communities that evolved to
permit survival of the community as a whole

6. Biofilm
• Structure
• Formation
• Properties
• Oral biofilm – An ecosystem
• Dental Plaque – A Biofilm
• Biofilm – Role in Periodontal Health & Diseases
• Molecular Genetics of biofilm
• Biofilm - Methods to study
• Strategies of therapy

7. Biofilm
• Structure
• Formation
• Properties
• Oral biofilm – An ecosystem
• Dental Plaque – A Biofilm
• Biofilm – Role in Periodontal Health & Diseases
• Molecular Genetics of biofilm
• Biofilm - Methods to study
• Strategies of therapy

8. • Three Components
1. Surface for Attachment
2. Biofilm Community
3. Bulk Fluid

9. 1. Attachment Surface
- Non Shedding Surface
- Shedding Surface
2. Biofilm Community
1. Micro colonies of bacterial cells -dense layer & loose layer
(15 - 20%)
2. Matrix of glycocalyx (75 -80%)with open fluid filled channels
Organic & Inorganic components.
Exopolysaccharides are the major component
Types 1. neutral or charged
2. ordered or disordered
3. Bulk Fluid
Stationary sublayer
Layer of fluid in motion

10. Biofilm
• Structure
• Formation
• Properties
• Oral biofilm – An ecosystem
• Dental Plaque – A Biofilm
• Biofilm – Role in Periodontal Health & Diseases
• Molecular Genetics of biofilm
• Biofilm - Methods to study
• Strategies of therapy

12. Formation of conditioning film (pellicle)
By selective adsorption of macromolecules.
Components:
Glycoproteins (mucins)
Proline rich proteins
Phospho protein (statherin)
Histidine rich protein
Enzymes (amylase)
Sialic acid
They act as receptors.

13. Role of Cryptitopes in bacterial adhesion.
- They are hidden receptors
- Hidden molecular segments undergo
conformational changes as they adsorb to apatite
crystals.
- They also become exposed by enzymatic action
(proteases)

14. Initial or Primary colonization
Transport to the surface
Brownian movement
Active movement
Initial adhesion
DLVO theory (Derjagvin, Landau, verwey, overbeek)
Total interaction energy is summation of electrostatic
(repulsive) and Vander Waals (attractive) force.

15. Three stages
1. Secondary minimum (reversible attraction)
2. Positive maximum (energy barrier)
3. Primary minimum (irreversible attraction)

16. Attachment of bacteria - firm anchorage
between pellicle and bacteria
1. Force generating movement of bacteria by
flagella
- to overcome the repulsive force (positive
maximum)
2. By mean of fimbriae, fimbrils
3. Cell surface proteins – adhesins

17. Co-Aggregation - Co-adhesion
• Ability of two genetically distinct bacteria to
recognize and adhere to one another in termed as
co-aggregation.
• 1st reported by Gibbson & Nygaard in 1970 as
inter bacterial aggregation.
• Co-adhesion - attachment of planktonic bacteria
to recognize and adhere to already attached
bacteria. Can be intra species or interspecies.

19. Basic principles of Co-aggregation
1. Specificity
It is highly specific and not random.
Mediated by receptors and adhesins
Receptors - usually polysaccharide
Adhesin - lectin
Two types
lactose inhibitable
lactose non inhibitable

20. Streptococcus - actinomyces
Kolenbrander & Anderson(1990)

21. Specific associations in dental biofilm
Socransky & Haffajee (1998)

22. 2. Functional similarity
Even though structurally distinct but functionally similar
adhesins on each species can bind to the same receptor on
common partner.

24. 3. Co-aggregation bridging
• This is formed when the common partner bears
two or more types of co-aggregation mediators.
It can be various polysaccharide receptors
Or
Various adhesins
Or
Mixture of two

26. 4. Co-Aggregation competition
Competition occurs when
multiple cell types
recognize the same co-
aggregation mediator on
the common co-
aggregation partner.

27. Role of early colonizer in co-aggregation
Reasons for numerical dominance of streptococci in early colonizers.
1. Ability to bind to non shedding surface
2. Less sensitive to exposure to air
3. Intra generic co-aggregation.
Major surface proteins in streptococci which help in co-adhesion
- SspA and Ssp B – (adhesins)
- Polysaccharide receptors
Ssp protein also mediate attachment to pellicle
• Majority of co-aggregation partners of S-oralis, S-sanguis,
S-mitis, S-gordoni are gram –ve
• Receptors and adhesins borne on the same cell do not recognize each
other.

28. F-nucleatum – Co-Aggregation bridge
F nucleatum can bind to both early and late
colonizers.
F nucleatum –> Pg, Aa, T denticola
galactose specific leutin like adhesin
F nucleatum -> streptococci
arginin inhibitable adhesin(Rad A)
Thus binding of F nucleatum to streptococci will
not occupy all of the fusobacterial adhesins.

29. P gingivalis – Co Adhesion
Constituent of both supra and sub gingival Biofilm.
P gingivalis co-adhesion is through
Long fimbriae (Fim A)
Short Fimbriae (Mfa)
Arg-gingipain (rgP)B
Pgingivalis - streptococcus gordoni
Fim A - GAPDH (glycoraldehyde 3 phosphate dehydrogenase)
Mfa - Ssp Surface protein.
P.gingivalis does not co-aggregate with S.mutans
Pg strain (W83) does not form biofilm - no fimbriae

30. Synergism -antagonism

31. Aa - Co aggregation
• Long thick fimbrils composed of pili modulate
cell-surface, cell-cell interactions
• gene cluster. (flp-rcp-tad) is involved in
synthesis of the pili.
• PGA – linear polymer of N-acetyl - D - gluco
samine (extracellular polysaccharide) synthesis
by Aa helps in biofilm development.

32. T-denticola – Co Aggregation
• T denticola & Pg have synergestic interactions.
• Proteins which facilitate co-aggregation are
Dentilisin - with Pg
Cell surface Proteins -Msp, Prtp
flagella protein (flgE - gene)
Cytoplasmic filament protein (cfpA - gene)

33. Morphological Co-aggregation patterns
Rosette formation
• Seen in early biofilm
formation
• Single coccus
surrounded by large
number of cocci

34. Corn Cob Pattern
(Listgarten 1973)
Cocci - bacilli
usually seen in gingivitis.
F nucleatum - P gingivalis
- Actinobacillus
- Streptococcus
- Veillonella
Prevotella loescheii - S.oralis

35. Corn Cob Pattern

36. Test tube brush formation
• Bacilli - filamentous
organism
• usually seen in
Periodontitis.

37. Factors influencing development of
Biofilm
1. Factors related to attachment surface.
2. Factors related to Biofilm community
3. Factors related to bulk fluid
4. Environmental factors

38. Factors related to attachment surface
1. Physical factors
Surface roughness - se surface area
- protection from shear force
- se difficulty in cleaning
• chemical composition of the surface.
- brass reduces attachment
- polyvinyl chloride encourages biofilm growth.
Type of tissue and the genetic background of the host
which might alter the receptors

39. Factors related to Biofilm community
Role of Exopolysaccharides
a. Maintain biofilm structure – networked cross linked linear
macromolecules
b. Chemical composition and tertiary structure determine the adhesive character and
hydrophilic or hydrophobic nature.
c. Protect the microorganism – from desiccation, harmful agents
d. Create a nutritional environment
- by binding cations
- by retaining extracellular enzymes
e. Act as a buffer

40. Role of Micro organisms
• Pre emptive colonization
• Through Co-aggregation
• Through metabolic interactions

41. Factors related to bulk fluid
Saliva - for supragingival
GCF - for subgingival
Bulk fluid provides nutrients, remove waste products and act as a vehicle for
transport of bacterial cells.
bulk fluid influence through
1. Cohesiveness of fluid
2. Composition
- nutrient content
- antibacterial agents
3. Hydrodynamics
- shear force
high shear forces (turbulent flow) - thinner and denser -
elongated with streamers, capable of oscillation or patches of ripples
low shear forces (laminar flow) - thicker with voids - like
tower or mushroom

44. Environmental Factors
1. Addition of nutrients
2. Osmolarity
3. pH
4. Iron availability
5. Oxygen tension
6. Temperature
7. Physical barrier - availability of space
8. Chemical & biologic barrier

45. Biofilm
• Structure
• Formation
• Properties
• Oral biofilm – An ecosystem
• Dental Plaque – A Biofilm
• Biofilm – Role in Periodontal Health & Diseases
• Molecular Genetics of biofilm
• Biofilm - Methods to study
• Strategies of therapy

46. 1. Physiological heterogeneity
2. Functional heterogeneity
3. Metabolic interaction
4. Communication
5. Horizontal gene transfer
6. Antimicrobial resistance
7. Increased virulence
8. Detachment

47. Physiological heterogeneity
• Cells of same microbial species can exhibit
different physiological states within a biofilm.
• pH can vary over a short distance in a biofilm.
• No: of metal ions differ in a biofilm.
• Conc: of oxygen and other gases (CO2, NH3 etc)
differ.

48. Functional heterogeneity
Due to
Poly microbial nature
- metabolically diverse bacteria contribute
Functional differentiation
- cells residing on superficial areas are more
resistant to antimicrobials than at the
attachment surface.
Cell to cell communication

49. Metabolic interaction

50. Antagonistic interactions
• Through the production of
H2O2 and bacteriocins.
• Streptococcus cristatus
inhibit P-gingivalis
colonization.
- by downregulating Fim A
expression.

51. Communication
• Quorum sensing
• Intercellular communication through
accumulation of signaling compounds that
regulate the expression of specific genes which
allow the bacteria to mount co-ordinated response
to their environment.
• Quorum sensing in biofilm was 1st reported by
Cooper et al 1995 and in oral biofilm by Lijemark
1997

52. General properties of quorum sensing signaling
molecules
• It is a two component system.
• Continuously expressed
• Cell density dependent
• Evolutionarily conserved
• It can bring about inter species and intra species
communication.

53. Quorum sensing facilitates
1. Genetic competence
2. Antibiotic resistance
3. Encourage the growth of beneficial species.
4. Discourage growth of competitors

54. Types of Quorum sensing molecules
Autoinducer 1
1st detected in Vibrio fisheri - by Nealson et al 1979
Chemically – N – Acyl Homoserine Lactone(AHL)
Proteins involved are designated as
Lux I & Lux R
Lux I - Catalyses the synthesis of AHL
Lux R - transcriptional regulator
Autoinducer 1 is not common in oral biofilm.
It usually regulates gene expression in genetically identical cells.

56. Autoinducer 2
First observed by Schauder et al 2001
• Collection of molecules formed from spontaneous rearrangement of 4,5
dihydroxy-2-3 pentanedione (DPP)
• Produced by both gran +ve & -ve organism
• Gene responsible for it production - lux S - protein - LuxS
• In the absence of two component response circuit (receptor protein)
auto inducer does not function in cell-cell communication but functions
in basic metabolism - catalyses methyl cycle.
• Autoinducer 2 mediate gene expression in mixed communities.
• It is also density dependent
• Commensal bacteria respond to low levels and pathogenic bacteria
respond to high levels of autoinducer 2

57. Other functions of autoinducer 2
1. Regulate iron uptake in Aa
2. Regulate hemin (iron source) acquisition in Pg.
3. Regulate enzymes involved in stress related function.
4. Control the formation of multi species biofilm.
5. Induces expression of leukotoxon in Aa and modulate
protease activities in Pg.

58. Competence stimulating peptide(CSP)
• This mediate quorum sensing in S.mutans
• Increase genetic competence
(transformation frequencies)
• Increase acid tolerance in recipient cells
within biofilm.
• It is also cell density dependent
• Two component system.

59. Horizontal gene transfer
Mobile genetic elements in the oral bacteria.
1. Those that transfer from cell to cell.
eg: conjugative plasmids
conjugative transposon
genomes of bacteriophage
2. Those that only capable of transposition within
genome.
eg: insertion sequence, intergrons, genomic
islands, class II transposon,mobile introns

60. • Plasmid - It is an extra chromosomal
genetic element consisting of DNA
situated in the cytoplasm in free state and
reproducing independently.
• They are grouped in compatibility groups
(inc groups) based on their ability to co-
exist in the same cell.

61. • Transposon - segment of DNA that has the ability
to move around between chromosomal and extra
chromosomal DNA molecules within cells. It is
also called jumping genes.
• It is a segment of DNA with one or more
genes in the centre and two ends carrying inverted
repeat sequence nucleotide which are
complementary to each other but in reverse order.
It usually encodes an enzyme tranposase.

63. • Bacteriophage - viruses
that parasitize bacteria
and consist of nucleic
acid core and a protein
coat.

64. Mechanisms of horizontal gene transfer
1. Transformation
2. Transduction
3. Conjugation

65. Transformation
• It is the transfer of
genetic information through
the agency of free DNA.
(source free DNA - dead
bacteria)
• Competence is the
physiological state in which
cell can take up DNA.

66. Successful transformation depends on
1.Physical & Chemical factors
• Size, conformation, origin and conc: of DNA
• UV light
• Salt
• pH
• Temperature
• Nucleases in the environment
2. Genetic Factor
• Presence of restriction system in transformant
• Ability of the incoming DNA to replicate
autonomously or integrate in to recipient’s genome.

67. Transduction
• It is the transfer of a portion of DNA from one bacterium to
another by a bacteriophage.
• In transduction bacterial DNA is erroneously packaged in to
phage head and when the phage infects other bacteria it
injects that bacterial DNA.
• Bacteriophage can also bring about lysogenic conversion
(phage genome enter the bacterial genome and results in
phenotypic change)
• Bacteriophage contribute more to virulence transfer than to
antibiotic resistance.

68. Transduction

69. Conjugation
Process whereby a donor bacterium (having sex
pili) make physical contact with the recipient
bacterium and transfer genetic element in to it
through a conjugation tube.
Mediated by conjugative transposon and
conjugative plasmid.
eg: tet B - efflux gene for tetracycline resistance
is transferable between strains of Aa and Aa &H
influenza by conjugative plasmid

71. Antimicrobial Resistance
Biofilm bacteria are resistant to:-
- removal due to firm attachment & matrix
- surfactant
- innate immune response - release of
membrane vesicles & cell wall
fragments which act as decoy
receptors.
- antimicrobial agents.

72. Resistance to Antimicrobial agents
Streptococcus sobrinmus in biofilm is resistant to
Chlorhexidine - 300 times greater than planktonic form
Amine fluoride - 75 times greater
Streptococcus sanguis is resistant to
Chlorhexidine - 10-15 times greater
Vancomycin - 1000 times greater.
Older plaque is more tolerant to antimicrobials than younger plaque.
Increased resistance in biofilm depends on
1. species
2. type of antibiotic
3. habitat

73. Mechanisms of increased antibiotic resistance
1. Slower growth rate
slower growing bacteria over express non specific defence
mechanism including shock proteins and multi drug efflux pump
(arc AB) and demonstrate increased expolymer synthesis.
2. Expolymer matrix can retard the diffusion of drug and concentrate
extra cellular enzymes such as β lactamase
3. Over expression of antibiotic resistant gene – through horizontal
gene transfer.
4. Super resistance bacteria in biofilm – multi drug resistance pump.

74. Increased virulence
• Community life style lead to more
virulent phenotype by differential gene
expression.
• S gordonii contribute to the conversion of
Pg to a more virulent phenotype through
formimino – tetrahydrofolate biosynthesis
pathway.

75. • Link was found between pathogenisity of organism and
their ability to degrade histidine

76. Detachment or dissemination

77. By active or passive means
by growth & motility of organisms environmental influence
Cells detach in different fashions.
1. Erosion - detachment of single cells in a continuous
predictable fashion.
2. Sloughing - sporadic detachment of large group of cells
3. Intermediate - large groups in predictable manner
4. Bodily movement of biofilm en masse

78. Biofilm
• Structure
• Formation
• Properties
• Oral biofilm – An ecosystem
• Dental Plaque – A Biofilm
• Biofilm – Role in Periodontal Health & Diseases
• Molecular Genetics of biofilm
• Biofilm - Methods to study
• Strategies of therapy

79. Ecosystem
An ecosystem consists of the biological community
that occurs in some locale and the physical and chemical factors
that make up its non-living or abiotic environment.
Habitat - it is the site at which a population or community
grows, reproduces or survives.
Niche - functional role of an organism in a habitat.
Hierarchy
Ecosystem community population single organism .
Habitat affect the community and the community affect its habitat.

80. Influence of habitat on microbial composition
Around 700 species are identified
Composition of oral micro flora varies significantly at
distinct surfaces within the mouth.
Three similar clusters are identified (Mager et al 2003)
1st - dorsum and lateral aspect of tongue and saliva
2nd - other soft tissues of oral cavity.
3rd - supra and sub gingival plaque.
Between the clusters 1st & 2nd are more similar

82. Influence of disease on ecological shift and
microbial composition

83. Species habitat interaction in gingivitis

84. Climax Community
The interaction between the microbial and non
microbial components of an ecosystem ultimately
lead to a form of stabilization in which microbial
and non microbial forms exist in harmony and
equilibrium with their environment. This is termed
as climax community.
It is stable over time
It is dynamic - cells are dying & being replaced
Can be modified by exogenous forces.

85. Developed dental plaque represent Climax community

86. Biofilm
• Structure
• Formation
• Properties
• Oral biofilm – An ecosystem
• Dental Plaque – A Biofilm
• Biofilm – Role in Periodontal Health & Diseases
• Molecular Genetics of biofilm
• Biofilm - Methods to study
• Strategies of therapy

88. Biofilm
• Structure
• Formation
• Properties
• Oral biofilm – An ecosystem
• Dental Plaque – A Biofilm
• Biofilm – Role in Periodontal Health & Diseases
• Molecular Genetics of biofilm
• Biofilm - Methods to study
• Strategies of therapy

89. Role of biofilm in periodontal health & diseases
1. Biofilm bacterial cell fragment shedding
governs innate host response

90. 2. Biofilm composition influence innate host
inflammatory surveillance.
Non destructive microbial flora –
symbiotic relationship with host

91. Benefits of resident flora
Act as a barrier - colonization resistance to
pathogens
Mechanisms
Enhanced competitiveness,
Occupation of potential attachment sites,
Production of inhibitory compounds,
Development of an environment not
conducive to pathogens.

92. 3. Microbial shift influence destructive
inflammatory response.
• Pathologic flora - dysbiosis.
• Through the virulence factors
• Biofilm influence expression of bacterial virulence.
• Pg can be considered as an opportunistic pathogen -
opportunity to be a pathogen may be provided by
the right combination of other bacteria

93. Microbial flora in health & disease

94. Microbial flora in health & disease

95. Changing views about microbial etiology
Non specific plaque hypothesis - entire plaque
flora is responsible
Specific plaque hypothesis - specific pathogens
in plaque is responsible (Loesche 1976) .
Microbial shift hypothesis - due to decrease in
the no: of beneficial symbionts and/or increase in
the number of pathogen (dysbiosis)
Ecologic plaque hypothesis - change in the
environment (habitat) increase competitiveness
of putative pathogen (Marsh 1991)

96. Ecological plaque hypothesis in periodontal
diseases

97. Biofilm
• Structure
• Formation
• Properties
• Oral biofilm – An ecosystem
• Dental Plaque – A Biofilm
• Biofilm – Role in Periodontal Health & Diseases
• Molecular Genetics of biofilm
• Biofilm - Methods to study
• Strategies of therapy

98. Genes required for biofilm development are
mainly
1. Surface adhesion for cell to cell & cell to
surface interactions
2. For quorum sensing
3. environmental sensing two component
systems
4. General stress response.

99. Genes & proteins expressed in Streptococcus gordonii - a
primary colonizer
AbpA, AbpB - amylase binding protein
Hsa - sialic acid binding proteins
bind to salivary mucins & platelets.
SSaB - adhesin
LuxS - autoinducer 2
brpA - biofilm regulatory protein A
Com D - competence for genetic transformation
HK/RR 11 - two component regulatory system – role
in biofilm development.
mvt T - DNA replication/ repair
PBP2B, PBP5, glmM bacc A- peptidoglycan biosynthesis

100. Genes & proteins expressed in Aa
flp - rcp-tad - gene cluster for long thick fimbrils
moaA, moeA - synthesis of molybdenum
cofactor (Moco)
OMP34 - heat modifiable surface protein
pgaa ABCD - for synthesis of PGA - a linear
polymer of N-acetyl - D-
glucosamine in β linkage(component
of extracellular matrix)
Crp (cyclic AMP receptor protein) - global regulatory
protein of sugar metabolism.

101. Genes & proteins expressed by P gingivalis
Around 486 genes are differently expressed in biofilm.
83 up regulated 403 down regulated
Up regulated genes - transport and binding proteins.
Down regulated genes -
Cell envelope biosynthesis
DNA replication
Energy production
Biosynthesis of co factors
Prosthetic groups and carriers
Fatty acid and phospholipids metabolism and central
intermediary metabolism

102. Biofilm
• Structure
• Formation
• Properties
• Oral biofilm – An ecosystem
• Dental Plaque – A Biofilm
• Biofilm – Role in Periodontal Health & Diseases
• Molecular Genetics of biofilm
• Biofilm - Methods to study
• Strategies of therapy

103. Methods to grow biofilm
1. Static systems
- good method to inspect the biofilm in early
development
- cannot be used to study different stages of
biofilm development
2. Flow cell systems (nutrients constantly flowing system)
- Can be used to examine biofilm development
under different growth conditions
Methods to measure biofilm environment
- miniature micro electrode – to measure pH and solute
- micro sensor - to measure the conc: of oxygen and other
gases

104. Detection of bacterial species in biofilm
1. Light microscopy - rapid but limited in the precision of
identification
2. Dark field microscopy - rapid, only for motile organisms, limited
in precision.
3. Electron microscopy - fine distinction of bacterial species based
on cell wall structure and various appendages
- can not identify a cell to the species level.
- can not be used for hydrated samples
4. Confocal microscopy
Allows visualization of fully hydrated samples with delineation
of spatial arrangement of organism.

105. Confocal image of biofilm

106. 5. Culture
- identification based on phenotypic and
biochemical criteria.
- useful in antibiotic sensitivity assessment
- time consuming
- many biofilm bacteria are not cultivable.
6. Immuno diagnostics
- based on identification of specific antigen
through antibodies.
- limited only to certain species.

107. Molecular Diagnostics
- Based on DNA or RNA sequence
- improved sensitivity & specificity
Example:
• FISH (Fluorescent in situ hybridization)
- oligo - nucleotide probe
- to identify and localize particular species within
biofilm community
• Checker board hybridization
• Quantitative PCR
- Real time PCR
- Quantitative reverse transcription PCR
• T-RFLP – (Terminal restriction fragment length polymorphism)
- based on position of a restriction site close to a
labeled end of an amplified gene.

108. Pyrosequencing
• Successful incorporation of
nucleotide into nucleic acid
template leads to release of
pyrophosphate which in turn
converted to ATP and trigger
enzymatic cascade leading
to luminescence signal.
• Since the order in which the
nucleotide added is known,
according to the
luminescence burst (ccd
camera) the template
sequence and its quantity
can be reconstructed.

109. • Microarrays - identify micro organisms and the
expression of genes. They identify key
genes that are switched on&off during
different stages of bacterial interactions.
• High density microarray - contain thousand
to million probes
• Low density microarray - contain hundred to
thousand probes.

110. Next generation sequencing
Three generations 1st 2nd & 3rd
1st - rely on DNA amplification
- do not permit single molecule detection
2nd & 3rd - can detect single molecules

111. Chronology of various diagnostic techniques

112. Biofilm
• Structure
• Formation
• Properties
• Oral biofilm – An ecosystem
• Dental Plaque – A Biofilm
• Biofilm – Role in Periodontal Health & Diseases
• Molecular Genetics of biofilm
• Biofilm - Methods to study
• Strategies of therapy

113. 1. Mechanical debridement
2. Kill or affect the metabolism of organism. –
antiseptics, antibiotics, photodynamic therapy.
3. Alter the habitat
- diminish nutrient availability
- reduce gingival inflammation
4. Replacement therapy-probiotics
5. Vaccines

114. Future Approach
Based on the proteome and transcriptome of biofilm community.
a. Target the signaling molecules and disrupt the network
formation and inhibit the biofilm development.
b. Selective elimination of particular pathogens by targeted
antimicrobial peptide.
eg: CSP fused to antimicrobial peptide against S.mutans.
SMP - 28(antimicrobial peptide) linked to IgG specific for P
gingivalis surface components.
c. Identification of pathogenic genes by functional microarrays
and blockage of the same.

115. To Conclude
• Biofilms are spatially & functionally organised
metabolically interconnected microbial ecosystem.
• Features such as functional differentiation,
communication and division of(metabolic) labor
collectively makes us to consider biofilm community
holistically even as a primitive multicellular organism.
• Habitat is equally important in determining the
biofilm community.
• Thus periodontal therapy should also be directed
on these aspects instead of targeting individual species
alone

116. References
• Periodontology 2000 vol.14 1997, 12-32
• Periodontology 2000 vol.28 2002, 12-55
• Periodontology 2000 vol.38 2005, 135-187
• Periodontology 2000 vol.42 2006, 27-35
• Periodontology 2000 vol.42 2006, 47-79
• Periodontology 2000 vol.42 2006, 7-26
• Periodontology 2000 vol.52 2010, 38-52
• Periodontology 2000 vol.55 2011, 16-47
• Periodontology 2000 vol.55 2011, 70-86
• Clinical Periodontology 10th edition: Carranza,
Neuman &Takei

117. 24 Jan 09