Lecture 6: Microbial Growth Flashcards
What is a biofilm? (3 part definition)
Microbial communities (1), attached to a surface (2), covered with a protective matrix (3)
What are these cells called?
What are their characteristics?
What do they initiate?
Planktonic cells
Free-living, often motile cells
Initiate the 1st step of biofilm creation
What is stage 1?
What happens in stage 1?
- Attachment Phase
- Planktonic cells attach to a surface
- Pre-conditioning helps
- Pili play an important role
- Adherence proteins in cell membrane also help with attachment
What is stage 2?
What happens here?
What is a specific process that cells use in this stage?
Colonization Phase
Cells lose their motility, increase in cell #
Use Quorum Sensing: density dependent, cell to cell signaling.
Once a certain quorum is reached (cell density), it activates gene expression on individual cells to make a protective matrix of polysaccharides, proten and DNA
What is stage 3?
What happens here?
Maturation Stage
Form mushroom looking structures with channels for nutrients and oxygen gradients
What is stage 4?
Dispersal
What are dental carries and how does bacteria affect the teeth?
Dental carries are tooth decay
Dental plaque is a biofilm with more than 300 microbial species
The bacteria ferment, which creates an acidic environement that then breaks down enamel
Ex: Streptococcus mutans
What is periodontal disease?
What is a contributing bacteria?
Microbial infection with inflammation and tissue destruction
Porphyromonas gingivalis
What are microbes that grow in extreme environments called?
Extremophiles
What is this organisms relationship with oxygen?
Obligate aerobe
Need oxygen
What is this organism’s relationship with oxygen?
Facultative anaerobe
Prefers oxygen
What is this organism’s relationship with oxygen?
Aerotolerant anaerobe
Ignores oxygen
What is this organism’s relationship with oxygen?
Obligate anaerobe
Oxygen is toxic
What is this organism’s relationship with oxygen?
Microaerophile
Needs oxygen, but in a specific % range
What is this a picture of?
What domain is it in?
What genus?
Picture of extremophile (hyperthermophile) in domain Archaea
Genus: Geogemma
Strain 121: survives at 121 degrees C
