Lecture 3 Growth

Question 1

What are the four requirements for growth?

Answer 1

1) Elements for synthesis of new cellular materials
2) Components of cell it is unable to synthesise itself
3) Inorganic elements for support of cellular enzymes
4) Source of energy

Question 2

What do you need to grow bacteria in?

Answer 2

A nutrient or luria broth.

Both contain mixtures of amino acids, carbohydrates, vitamins and other growth factors.

Question 3

What agar does S. aureus need to grow in?

Answer 3

Mannitol/salt agar.

S. aureus has a high tolerance for NaCl, this agar is 7.5% NaCl which inhibits most competing organisms

Question 4

What colour colonies do lactose fermenters (e.g E.coli) produce?

Answer 4

Red and pink colonies.

Question 5

What colour colonies do lactose non-fermenters produce?

Answer 5

White colonies

Question 6

What does MacConkey agar contain?

Answer 6

Bile salts and crystal violet to inhibit gram positives. Contains lactose as a carbon source.