LG 5.8 - Growth of Bacteria

Question 1

Define colony?

Answer 1

• Population of cells arising from a single cell or endospore, or from a group of attached cells.

Question 2

Define pure culture?

Answer 2

• Only one species or strain.

Question 3

Define mixed culture?

Answer 3

• Various species or strains.

Question 4

Roughly, what is the cycle of binary fission?

Answer 4

• Way that bacterial cells replicate.

- Double their contents and divide in half.

Question 5

What is an aerotolerant anaerobe? Micro-aerophile?

Answer 5

• Aerotolerant: only anaerobic growth, but continues in presence of oxygen.
• Micro: only aerobic growth, oxygen required in low concentration.

Question 6

(7) What is the definition of fermentation?

Answer 6

• any metabolic process that releases energy from a sugar or other organic molecule, does not require O2 or an ETC, and uses an organic molecule as the final electron acceptor. Does not use Krebs cycle.

Question 7

(7) What is the downside to fermentation?

Answer 7

• Only produce 1 or 2 ATPs per starting molecule.

Question 8

(7) What is the difference between planktonic phenotype and biofilm phenotype?

Answer 8

• Planktonic: “free floating”, may be motile.

- Biofilm: “Sticky, slimy, tenacious”. mixed, heterogenous, dynamic, slime covered city.

Question 9

(7) Mixed, heterogenous, dynamic,

slime-covered?

Answer 9

• Mixed: many different types of bacteria present.
• Heterogenous: inside the biofilm there may be several different types of environments (O2, pH, etc.).
• Dynamic: planktonic “showering”, movment.
• Slime-covered: water, polysaccharide,

Question 10

(8) Why are biofilms more antibiotic resistant?

Answer 10

• Largely phenotypic: persister cells that are inactive, highly protected. altered gene transcription.
• Heterogeneous and mixed
• Slow-growth/ dormant
• matrix
• close proximity for resistance gene exchange