Physiological Characteristics: Hydrolytic and Degradative Reactions (Exercise 37)

Question 1

Fat Hydrolysis Testing

Answer 1

Media: Spirit Blue Agar

Enzyme: Lipase

Reaction: Triglycerides–>lipase–>glycerol + fatty acids

Fatty acids decrease pH, which causes a dark blue precipitate, glycerol droplets may also be present.

Question 2

Starch Hydrolysis

Answer 2

Media: Starch medium

Enzyme: Amylase

Indicator: Iodine

A starch indicator, iodine, is used to look for zones of clearing.

Question 3

Urea Hydrolysis

Answer 3

Indicator: Phenol Red

Enzyme: Urease

Urease breaks down urea releasing ammonia causing an increase in pH and a color change to pink.