Lecture 8-MT2

Question 1

What strains of bacteria are always found in yogurt?

Answer 1

-Streptococcus thermophilus
-Lactobacillus bulgaricus

Question 2

Psychrotrophiles

Answer 2

Bacteria that love low temperature
-0 to 10 degrees celsius

Question 3

Mesophiles

Answer 3

Bacteria that live in middle temperatures
-10 to 50 degrees celsius

Question 4

Thermophiles

Answer 4

Bacteria that love higher temperatures
-40 to 70 degrees celsius

Question 5

Hyperthermophiles

Answer 5

Bacteria that love very high temperatures
-65 to over 100 degrees celsius

Question 6

What is the the optimal temperature for S.thermophilus and L.bulgaricus

Answer 6

Both bacteria are thermophiles
-Optimal temp = 43 degrees celsius

Question 7

What is the optimal temp for Lactococcus lactis and Lactobacillus acidophilus?

Answer 7

Both bacteria are mesophiles
-Optimal temp = 39 degrees celsius

Question 8

Are S. thermophilus and L. bulgaricus Gram (-) or (+)

Answer 8

Gram (+)

Question 9

Streptococcus and Lactobacillus ferment lactose and produce lactic acid via?

Answer 9

Homolactic fermentation

Question 10

Anabolic vs catabolic?

Answer 10

-Anabolic: synthesis of organic compounds (makes things)
-Catabolic: breaks down organic compounds

Question 11

How do we make energy (which pathway) and why?

Answer 11

Cellular respiration
-Makes a lot of ATP

Question 12

Why do we use O2 in respiration?

Answer 12

Oxygen is the best electron receptor

Question 13

What are the products of glycolysis?

Answer 13

2 ATPs are made per glucose

Question 14

True or false: Fermentation is a pathway to make energy

Answer 14

False
-fermentation is NOT a pathway to make energy b/c it has no ETC
-fermentation is just a way for glycolysis to continue

Question 15

Homolactic fermentation

Answer 15

Leads to production of ONE fermentation product
-Lactate (lactic acid)

Question 16

Heterolactic fermentation

Answer 16

Leads to production of MORE than one product
-lactate, ethanol, and CO2

Question 17

What kind of O2 requirement do S. thermophilus and L.bulgaricus have?

Answer 17

Faculatative anaerobes

Question 18

True or false: strictly aerobe bacteria exist in yogurt

Answer 18

False
-will never find strictly aerobe bacteria in yogurt b/c they will not ferment

Question 19

How does casein help with yogurt production?

Answer 19

When pH drops below 4.6 calcium casein forms casein
-Casein denatures at low pH and separates from whey
-milk curdles–>denaturation of casein occurs

Question 20

True or false: S. thermophilus cannot catabolize galactose

Answer 20

True

Question 21

True or false: L. bulgaricus can catabolize galactose

Answer 21

True
-Can catabolize galactose but prefers GLUCOSE

Question 22

Why is Lactobacillus significant for pH

Answer 22

Helps maintain acidic pH in vagina
-lower than 4, during pregnancy protects pathogenic bacteria from growing