introduction of biofilm in microorganisms and stage of biofilm formation and method of detected biofilm-forming bacteria.

1. Biofilm
presentation
by
Marwa A. Al-Asady

2. Introduction of biofilm
 There are two types of growth patterns present in the bacterial cell
include planktonic cell (single cell) and sessile aggregate, which known
as the biofilm.
 So, biofilm can be defined as complex sessile communities of microbes
adhering to each other to biotic or non-biotic surfaces and buried firmly
in a self-produced extracellular matrix (ECM) composed mainly of
extracellular polysaccharide (EPS), proteins such as amyloid-like fibers
(ALF) and nucleic acids.
 The microbial cells within biofilms are coordinated in a way with
considerable different physiology and physical properties, which
facilitates adherence of these microorganisms to bio-medical surfaces
Marwa A. Al-Asady

3.  Biofilm formation is a major virulence factor for Gram-positive and
Gram-negative pathogens responsible for serious chronic infections
such as chronic wound infections, pneumonia in cystic fibrosis
patients, osteomyelitis, and otitis media.
 Biofilm supports the bacterial growth. Biofilm are a common mode of
bacterial growth in nature and their presence has an enormous
impact on many aspects of our lives, such as sewage treatment,
corrosion of materials, food contamination during processing, pipe
collapse, plant-microorganisms interaction in the biosphere, the
formation of dental plaque…etc.
Marwa A. Al-Asady

4.  Biofilms major cause of Nosocomial infections. Microbial biofilms,
which often are formed by antimicrobial-resistant organisms, are
responsible for 65% of infections treated in the developed world.
 Biofilms are remarkably difficult to treat with antimicrobials.
Antimicrobials may be readily inactivated or fail to penetrate into the
biofilm. In addition, bacteria within biofilms have increased (up to
1000-fold higher) resistance to antimicrobial compounds, even though
these same bacteria are sensitive to these agents if grown under
plank tonic conditions.
Marwa A. Al-Asady

5. Composition of biofilm
 The principal significant composition of the biofilm matrix varies in
different bacterial strains at different growth stages.
 The structure of the extracellular polysaccharide substance (EPS) of
biofilm contain host factor, proteins (including enzymes), extracellular
DNA (eDNA), polysaccharide and water. These components truly make
them hardy and allow them to survive hostile conditions.
 Different natures of forces like the hydrogen bonds and electrostatic
force of attraction are responsible for holding the microbial cells
together in a biofilm and the interstitial spaces and the water channels
play a significant role in the flow of nutrients to every cell in the biofilm
Marwa A. Al-Asady

6. Steps of biofilm development
 Biofilm development can be divided into several key steps including
attachment, micro colony formation, biofilm maturation and dispersion;
and in each step bacteria may recruit different components and
molecules including flagella, type IV pili, DNA and polysaccharides.
 Bacteria living in a biofilm can have significantly different properties
from free-floating bacteria, as the dense and protected environment of
the film allows them to cooperate and interact in various ways. One
benefit of this environment is increased resistance to detergents and
antibiotics, as the dense extracellular matrix and the outer layer of
cells protect the interior of the community.
Marwa A. Al-Asady

7. Biofilms protects from Immune responses
 Bacteria embedded within biofilms are resistant to both immunological
and non- specific defense mechanisms of the body. Contact with a
solid surface triggers the expression of a panel of bacterial enzymes
which catalyze the formation of sticky polysaccharides that promote
colonization and protection.
 Phagocytes are unable to effectively engulf a bacterium growing
within a complex polysaccharide matrix attached to a solid surface.
This causes the phagocyte to release large amounts of pro-
inflammatory enzymes and cytokines, leading to inflammation and
destruction of nearby tissues
Marwa A. Al-Asady

8. Detection and measurement of biofilm
 Microscopic Examination (electron microscope)
 Quantitative detection (tissue culture plate method)
 Qualitative detection (Tube method)
 Molecular detection (PCR • RT-PCR • RFLP • RAPD).
Marwa A. Al-Asady

9. References
 Roy, R., Tiwari, M., Donelli, G., and Tiwari, V. (2018). Strategies for combating
bacterial biofilms: A focus on anti-biofilm agents and their mechanisms of action.
Virulence. 9(1): 522-554.
 Li, X. H., and Lee, J. H. (2017). Antibiofilm agents: A new perspective for antimicrobial
strategy. J. Microbiol. 55(10):753-766.
 Vasudevan, R. (2014). Biofilms: Microbial Cities of Scientific Significance. J. Microbiol
Exp. 1(3).
Marwa A. Al-Asady

10. Thanks for lessening