This document discusses the stages of formation, composition, and structure of microbial biofilms. It defines a biofilm as a group of microorganisms like bacteria that stick to surfaces and each other, embedded in an extracellular polymeric substance. The stages of biofilm formation include initial attachment, irreversible attachment, development, and maturation. The structure of a biofilm includes bacteria, polysaccharides, proteins, extracellular DNA, and water. The composition includes microbial cells, polysaccharides, proteins, DNA, RNA, and ions. Bacteria form biofilms to protect themselves from environmental stresses and antimicrobial agents.

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Tania Tabassum
2021-ag-2599
M.Phil. Chemistry (3rd)
Supervisor: Dr. M. Irfan Majeed
Submitted to: Dr. M. Adnan Iqbal
Dr. Shanza Rauf Khan
Department of Chemistry
University of Agriculture Faisalabad, Pakistan

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STAGES OF FORMATION, COMPOSITION &
STRUCTURE OF MICROBIAL BIOFILMS

4. Contents
OMicrobial biofilm
OForms of microbial growth
OFormation of biofilm
OStructure of biofilm
OComposition of biofilm
OConclusion
OReferences
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5. Microbial biofilm
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OA biofilm is any group of
microorganisms (bacteria)
O Microbial cells stick to
each other
OAdhere to a surface
OEmbedded in extracellular
polymeric substance (EPS)
Fig.1. Bacterial Biofilm

6. Extracellular Polymeric Substance (EPS)
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 Jelly-like material
 Secreted by microorganisms
Functions
O Act like glue in biofilm
formation
O Helps in aggregation
O Protects from antibiotics
O Protection from environmental
stresses such as temperature
Fig.2. EPS in Biofilm

7. Forms of Microbial Growth
1. Growth in planktonic form
• Isolated microbial cells
• Float freely in a fluid environment
2. Growth in biofilm form
• Microbial cells present in community
• Embedded in EPS & attached to surface
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Planktonic form Biofilm Form
Fig.3. Planktonic vs. Biofilm form

8. Example of biofilm
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O Dental plaque - a slimy buildup of bacteria
that forms on the surfaces of teeth.
O Streptococcus mutans bacteria responsible
for dental plaque
O Dental Plaque contains 400 different species
of bacteria
Fig.4. Dental Plaque

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Fig.5. Staphylococcus aureus Fig.6. Staphylococcus epidermidis
Biofilm forming bacteria

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Attachment Growth Dispersion/Detachment
1,
1. Initial
attachment
1,
2. Irreversible
attachment
5.
Dispersion
1,
4.
Maturation
1, 6.
Attachment
3.
Development
Fig.7. Stages of Biofilm Formation
Formation of Biofilm

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Bacterial
cell
Resistant
bacteria
Horizontal
Gene transfer
Protein Polysaccharides Extracellular DNA
Fig.8. Structure of biofilm
Structure of biofilm

12. Composition of Biofilm
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Components % of Matrix
Water Up to 97%
Microbial Cells 2-5%
Polysaccharides 1-2%
Proteins <1-2%
DNA and RNA <1-2%
Ions <1%

13. Bacteria form biofilms to protect themselves from:
O Environmental stresses such as UV radiation
O Antimicrobial agents
O Extreme temperature
O Limited nutrients
O Extreme pH
O High salt concentrations
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Conclusion

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• Castiblanco, L. F. and G. W. Sundin (2016). "New insights on molecular regulation
of biofilm formation in plant‐associated bacteria." Journal of integrative plant
biology 58(4): 362-372.
• Lohse, M. B., et al. (2018). "Development and regulation of single-and multi-
species Candida albicans biofilms." Nature Reviews Microbiology 16(1): 19-31.
• Toyofuku, M., et al. (2016). "Environmental factors that shape biofilm formation."
Bioscience, biotechnology, and biochemistry 80(1): 7-12.
References

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