12. Microbial Biofilms & their Biotechnological Applications

Question 1

what are the five stages of biofilm development?

Answer 1

• planktonic growth attached to surface
• the monolayer is formed and the matrix is being produced
• multi-layer microcolony is formed
• the characteristic ‘mushroom’ of ploysaccharides is formed, being the mature biofilm
• a new cycle starts as detachment and reversion to planktonic growth occurs

Question 2

what are the four structures of a mature biofilm?

Answer 2

• detatchment area
• core of biofilm
• adhesion area
• basis of biofilm

Question 3

why do microbes grow/live inside a biofilm?

Answer 3

• Protection
• Proximity to nutrients
• Micro-environments
• Ease of gene transfer
• Co-operative metabolism

Question 4

what are the uses of biofilms in the medical field? **

Answer 4

-

Question 5

what are the uses of biofilms in bioprocesses?

Answer 5

• wastewater treatment
  – granules consisting of microbial communities
  – granules described as collection of self-immobilized cells into spherical form (considered special case of biofilm growth)
• immobilisation of biofilsm onto support material
• biofilms are effective during bioleaching

Question 6

what is EPS?

Answer 6

• extracellular polymeric substance
• boundary between microorganisms and surrounding abiotic environments
• facilitates transformation of microenvrionment within biofilm
  – allowing niche and ideal conditions for proliferation of biofilm-associated microbial community in harsh environments
• compisition and quatity will vary depending on microorganisms age and environmental factors
  – neutral / polyanionic (gram +ve)
  – cationic nature (gram -ve)

Question 7

what are the roles of quorum sensing in the context of microbial biofilms?

Answer 7

• Attachment
  – the cell begins planktonic growth due to environmental and QS cues (proteins absorbed, and attachment to surface)
• Biofilm growth
  – The formation of the monolayer begins as the colony density has increased due to formation of specific enzyme
  – the multi-layer colony has formed, and colony density increases further
  – the mushroom is formed when colony density is at its highest without having produced a certain amount of specific QS enzymes
• Detachment
  – the detachment of cells from the mature biofilm occurs due cell growth and division, or the removal of the biofilm due to actions occuring from QS special enzymes.

Question 8

name three physical components of a biofilm

Answer 8

• eDNA
• EPS
• waterchannels