Basic Details of Biofilm.

1. Presented by : KRISHANCHAND MAHRA
B.Sc. Biotechnology
4th semester
17120010

2. INTRODUCTION
 Biofilms are a collective of one or more types of
microorganisms that can grow on many different
surfaces. Microorganisms that form bio films include
bacteria, fungi and protists.
 Biofilms have established themselves in such
environments for a very long time. Fossil evidence of
biofilms dates to about 3.25 billion years ago,
according to a 2004 article published in the journal
Nature Reviews Microbiology.

3. STRUCTURE OF BIOFILM

4. STRUCTURE OF BIOFILM
 A microbial biofilm is made up of many
prokaryotic organisms that combine to form
a colony. The colony is adhered to a surface
and coated with a polysaccharide layer (or
slime layer). The slime consists of many
porous layers with channels which allow the
cells in the centre of the colony to receive
nutrients and remove waste products.

5. FORMATION OF BIOFILMS
 Initial attachment - The formation of a biofilm begins
with the attachment of free-floating microorganisms
to a surface. The first colonist bacteria of a biofilm may
adhere to the surface initially by the weak van der
Waals forces and hydrophobic effects. If the colonists
are not immediately separated from the surface, they
can anchor themselves more permanently using cell
adhesion structures such as pili.

6.  Irreversible attachment- For most frequent attachment
and biofilm formation rough, hydrophilic and coated
surfaces will provide better environment. Increased
attachment may also occur due to increase but not
exceeding critical level in flow velocity, temperature of
water or nutrients concentrations. Presence of locomotor
structures on cell surfaces such as flagella, pili, fimbriae,
proteins or polysaccharides are also important and may
possibly provide an advantage in biofilm formation when
there are mixed community.

7.  Micro colony formation - Micro-colony formation
takes place after bacteria adhered to the physical
surface/biological tissue and this binding then
becomes stable which results in formation of micro-
colony. Multiplication of bacteria in the biofilm starts
as a result of chemical signals. The genetic mechanism
of exopolysaccharide production is activated when
intensity of the signal cross certain threshold . So by
this way using such chemical signal, the bacterial cell
divisions take place within the embedded
exopolysaccharide matrix, which finally result in
micro-colony formation.

8.  Maturation - After micro-colony formation stage of
biofilm, expression of certain biofilm related genes
take place. These gene products are needed for the EPS
which is the main structure material of biofilm. It is
reported that bacterial attachment by itself can trigger
formation of extracellular matrix. Matrix formation is
followed by water-filled channels formation for
transport of nutrients within the biofilm. Researcher
have proposed that these water channels are like a
circulatory systems, distributing different nutrients to
and removing waste materials from the communities
in the micro-colonies of the biofilm

9.  Detachment - Detachment of planktonic bacterial cells from the
biofilm is a programmed detachment, having a natural pattern .
Sometime occasionally due to some mechanical stress bacteria
are detached from the colony into the surrounding. But in most
cases some bacteria stop EPS production and are detached into
environment. Dispersing of biofilm cells occur either by
detachment of new formed cells from growing cells or dispersion
of biofilm aggregates due to flowing effects or due to quorum-
sensing . In biofilm of cells are removed due to an enzyme action
that causes alginate digestion. Phenotypic characters of
organisms are apparently affected by the mode of biofilm
dispersion. Dispersed cells from the biofilm have the ability to
retain certain properties of biofilm, such as antibiotic in-
sensitivity. The cells which are dispersed form biofilm as result of
growth may return quickly to their normal planktonic
phenotype.

10. Formation of biofilms

11. QUORUM SENSING
 During biofilm formation many species of bacteria are able to
communicate with one another through a mechanism called
quoreum sensing. It is a system of stimulus to co-ordinate gene
expression with other cells and response related to the density of
their local population. During quorum sensing signalling
molecules attach to receptors of new bacteria and help in
transcription of genes within a single species of bacteria as well
as between different bacterial species. QS system enables
communication between intraspecies and interspecies which
involves in terms of biofilm formation, food shortages and
environmental stress conditions, such as disinfectants,
antibiotics, bacterial colonization, the identification of annoying
species, the establishment of normal intestinal flora as well as
the prevention of harmful intestinal flora. Many clinically-
associated bacteria use QS for the regulation of the collective
production of virulence factors.

12. ADVANTAGES OF BIOFILMS
1. Bioremediation- Microorganism introduced to
consume and break down environmental
pollutants.
2. Biofilm in waste water treatment – Activated sludge
chamber contain microorganism to degrade organic
compound.
3. Microbial leeching- extracting metals from ores
with the use of microorganism.
4. Bioreacter
5. Biofilteration

13. DISADVANTAGES
1. Biofilms are major cause of infection-
Biofilms are implicated in otitis media, the most common acute ear infection in children in the
U.S. Other diseases in which biofilms play a role include bacterial endocarditis (infection of
the inner surface of the heart and its valves), cystic fibrosis (a chronic disorder resulting in
increased susceptibility to serious lung infection), and Legionnaire's disease (an acute
respiratory infection resulting from the aspiration of clumps of Legionnella biofilms detached
from air and water heating/cooling and distribution systems).
2. To Environment - Microbes can negatively impact environments on a global level
including producing and consuming atmospheric gases that affect climate; mobilizing toxic
elements such as mercury, arsenic and selenium; and producing toxic algal blooms and creating
oxygen depletion zones in lakes, rivers and coastal environments (eutrophication). Furthermore,
the incidence of microbial diseases such as plague, cholera, Lyme disease, and West Nile Virus
are linked to global change.

14. 3. To Industary - Biofouling, biocorrosion, equipment damage and
product contamination are constant and expensive problems in industry.
4. To Household items - Biofilms avidly colonize many household
surfaces, including toilets, sinks, countertops, and cutting boards in the
kitchen and bath. Poor disinfection practices and ineffective cleaning
products may increase the incidence of illnesses associated with
pathogenic organisms in the household environment.
5. To Implants - biofilms often form on the inert surfaces of implanted
devices such as catheters, prosthetic cardiac valves and intrauterine
devices.

15. THANK YOU