Week 5 (after midterm material)

Question 1

what are biofilms

Answer 1

Most prokaryotes and many microbial fungi prefer to grow in communities that stick together on organic/inorganic surfaces, forms specialized structures called biofilms

Question 2

Life cycle of biofilms

Answer 2

○ Form when and were nutrient are plentiful
○ Once nutrients are scarce they detach from community in search for new sources
○ Biofilms in nature can take different forms and serve different functions

Question 3

Formation of biofilms

Answer 3

-Attachment of planktonic bacteria through cell envelope/surface appendages
-Attached bacteria form microcolonies
-EPS secretion
-Biofilm elaboration and maturation, forms thick layered tower
-Lots of nutrients around, favourable to be released and dissolution and dispersal to colonize a different area
-Cued by different environmental signals
-Regulated by quorum sensing

Question 4

What is quorum sensing?

Answer 4

○ Assessing bacterial density
○ Autoinducers (signaling molecules) secreted into surroundings
§ Freely diffuses in and out of bacterial cells, binds to cytoplasmic receptor protein, a transcriptional regulator
§ At certain [ ] the transcription regulator is activated binds to DNA-activating quorum sensing regulated genes
§ Results in coordinated response by all cells in community
○ Extracellular [ ] of inducer increases with population density
○ Mechanism for regulating density dependent community behaviours

Question 5

How can biofilms be beneficial and detrimental

Answer 5

• Can be beneficial
  ○ Allows microbes to work together effectively
  ○ Normal microbiota biofilms of plants and animals are essential and beneficial
  
  • Can be detrimental
    ○ Damage equipment and infrastructure (concrete, pipes)
    ○ Colonize surface put into body (heart valves etc.)
    ○ Biofilms of pathogenic bacteria problems in medicine (tooth decay from plaque)
    ○ Biofilm bacteria highly resistant to antimicrobials and killing by immune response defenses

Question 6

Biofilms role in human health

Answer 6

○ Plays important role in medicine and infectious diseases
○ Pathogenic bacteria and fungi can form biofilms on human tissue, medical equipment and implanted devices
○ Difficult to treat with antimicrobials, significant clinical concern