This is a slide on BIOFILMS which I have prepared during my second semester of B.Tech Dairy Technology course. Hope this helps you :")

1. Topic :- Biofilms
Presented by:- Guided by:-
Tiasha Biswas Dr. Vaibhao Lule
Reg no:- D/19/007 (Asst.Professor)
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD)
Subject :- Microbiology of Fluid Milk (DM/202)
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2. Table Of Content
▪ INTRODUCTION
▪ WHEN MICROBES FORM BIOFILMS ?
▪ STEPS IN THE FORMATION OF BIOFILMS
▪ IDENTIFICATION
▪ HOW ARE BIOFILMS CHARACTERIZED?
▪ ULTRASTRUCTURE OF BIOFILM
▪ IMPORTANCE OF THE STRUCTURE OF BIOFILM
▪ FUNCTIONING OF BIOFILM
▪ BENEFITS OF BIOFILMS TO MICROBES
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD) 2

3. INTRODUCTION
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD)
Biofilm is an assemblage of microbial cells that is
irreversibly associated (not removed by gentle
rinsing) with a surface and enclosed in a matrix of
primarily polysaccharide material.
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4. INTRODUCTION
⮚ A biofilm is an assemblage of surface-associated
microbial cells that is enclosed in an
extracellular polymeric substance matrix.
⮚ Biofilms may form on a wide variety of
surfaces, including living tissues, indwelling
medical devices, industrial or potable water
system piping.
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD) 4

5. WHEN MICROBES FORM
BIOFILMS?
⚫ Mainly when they are capable of recognition of
specific or non-specific attachment sites on a surface.
⚫ Nutritional cues.
⚫ Exposure to planktonic cells to sub-inhibitory
concentrations of antibiotics.
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD) 5

6. STEPS IN THE FORMATION OF BIOFILM
❑ STEP 1: Planktonic (free floating) bacteria adhere to the
biomaterial surface.
❑ STEP 2: Cells aggregate, form micro colonies and excrete
extracellular polymeric substances (EPS), i.e. slime. The attachment
becomes irreversible.
❑ STEP 3: A biofilm is formed. It matures and cells form multi-
layered clusters.
❑ STEP 4: Three-dimensional growth and further maturation of the
biofilm, providing protection against host defense mechanisms and
antibiotics.
❑ STEP 5: The biofilm reaches a critical mass and disperses
planktonic bacteria, ready to colonize other surfaces.
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD) 6

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Dairy Technology (PUSAD) 7

8. Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD)

9. IDENTIFICATION
▪ A microbial biofilm is considered a community that meets the following
four basic criteria:
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD)
1) Must possess the abilities to self-organize.
(Autopoiesis)
2) Resist environmental perturbations.
(Homeostasis)
3) Must be more effective in association
than in isolation. (Synergy)
4) Respond to environmental changes as a
group rather than single individuals.
(Communality)
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10. HOW ARE BIOFILMS CHARACTERIZED
⚫ Biofilms are characterized by:-
1. Surface attachment
2. Extracellular matrix or polymeric substances
3. Structural heterogeneity
4. Genetic diversity
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD) 10

11. ULTRA STRUCTURE OF BIOFILM
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD)
• Composed primarily of microbial cells
and glycocalyx like matrix
(Extracellular Polymeric Substance).
• Fully developed biofilm is described as
heterogeneous arrangement of microbial
cells on a solid surface.
• Basic structural unit of a biofilm is the
micro colonies or cell cluster formed by
the surface adherent bacterial cells.
i. 85% :- Matrix (Polysaccharides,
Proteins, Nucleic acids and Salts)
ii. 15% :- Bacterial Cells
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12. IMPORTANCE OF THE STRUCTURE
OF BIOFILM
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD)
• Biofilm structure protects the residing bacteria from environmental threats.
• Structure of biofilm permits trapping of
nutrients and metabolic cooperativity between
resident cells of the same species and/or
different species.
• Biofilm structure displays organized internal
compartmentalization.
• Bacterial cells in a biofilm community
may communicate and exchange genetic
materials to acquire new traits.
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13. FUNCTIONING OF BIOFILM
⮚ Outermost layer
o Highest concentration of oxygen and nutrients, resembles their planktonic counterparts.
o They slough off and initiate biofilm formation downstream.
⮚ Middle layer
o Organisms here decrease their metabolic activities.
o Although they can clearly utilize the nutrients, exchange genes and have the potential for multiple drug
resistance.
o The benefit is obtained from their alignment in this layer which depends upon spatial arrangement,
physiologic heterogeneity and non uniformity.
⮚ Innermost layer
o Attached to the substratum and is the earliest part of the biofilm.
o Efficiently decrease the metabolic activities.
o Provides inheritance for future populations that transfer laterally.
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD) 13

14. BENEFITS OF BIOFILMS TO
MICROBES
Dept. of Dairy Microbiology, College of
Dairy Technology (PUSAD)
• Helps the bacteria to survive in unfavorable
environment and nutritional conditions.
• Resistance to antimicrobial agents.
• Increase in local concentration of nutrients.
• Opportunity of genetic material exchange.
• Ability to communicate between bacterial
population of same and/or different species.
• Produce growth factors across species
boundaries.
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Dairy Technology (PUSAD) 15
QUERIES

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Dairy Technology (PUSAD) 16