Lab 18 - Protein & Amino Acid Metabolism

Question 1

what are the 3 amino acid metabolic tests?

Answer 1

MIO test, Gelatin test, Urea test

Question 2

what does the MIO deep contain?

Answer 2

0.1% glucose
Amino acids
0.2% agar

Question 3

in MIO, once the bacteria run out of the small amount of glucose, what do they start metabolizing?

Answer 3

amino acids

Question 4

what are the 2 steps that bacteria metabolize amino acids?

Answer 4

1. They convert amino acids into organic acids by removing the amino group using the deamination reaction to produce ammonia (basic)
2. The organic acids are broken down to produce ATP

Question 5

what are the 3 things MIO tests for?

Answer 5

Motility, Indole, and Orithnine

Question 6

how do you know if an organism is motile in the MIO test?

Answer 6

if the bacteria is motile, it will be more turbid with diffused growth. One straight line that is clean means the organism is NOT motile.

Question 7

what is the indole test of the MIO asking?

Answer 7

Does the organism produce indole from tryptophan using tryptophanase? We add the Kovac’s reagent drop to see if the organism is positive indole or not

Question 8

what is a positive indole reaction in MIO?

Answer 8

a pink or red ring at the top after inserting Kovac’s reagent

Question 9

what is the ornithine test of the MIO asking?

Answer 9

Does the organism decarboxylate ornithine using ornithine decarboxylase?

Question 10

what is decarboxylate? what does it do?

Answer 10

it removes the carboxyl group, which makes the product that raises the pH, which makes the broth purple

Question 11

in the ornithine decarboxylase test of the MIO, what is the product that raises the pH of the media? what color does it make it?

Answer 11

Putrescine raises the pH of the media and the pH indicator becomes purple

Question 12

what is a positive ornithine decarboxylase test in MIO? negative test?

Answer 12

purple (or yellowish/purple)= positive
yellowish/green = negative

Question 13

in the MIO ornithine decarboxylase test, what is the correct inoculation + results of that?

Answer 13

by stabbing the MIO medium deep with a needle in a straight line, with leaving about a cm on the bottom. in a positive ornithine decarboxylase test, there should be some yellow at the bottom if it was inoculated correctly since the bottom of the tube shouldn’t have the inoculum.

Question 14

what is gelatin? what is its macromolecule?

Answer 14

It is a protein derived from the denaturation of collagen protein

Question 15

when is gelatin liquid and solid?

Answer 15

Liquid at room temperature, solid in the fridge/ice

Question 16

what are gelatinases or collagenases?

Answer 16

they are exozymes produced by organisms that are secreted out of the cell to break down gelatin into amino acids, which can then be transported inside the cell and catabolized for energy.

Question 17

what is the gelatin test?

Answer 17

testing if the bacteria makes gelatin

Question 18

what is a positive and negative gelatin test?

Answer 18

if the bacteria makes gelatin, the media will be liquid = positive
solid = negative

Question 19

what is the question that the urea test is asking?

Answer 19

does an organism break down urea using urease?

Question 20

what does the urea medium contain?

Answer 20

-urea
-glucose
-peptone
-phenol red (pH indicator)

Question 21

what does the phenol red pH indicator indicate?

Answer 21

yellow/orange < 8.4
pink > 8.4

Question 22

the breakdown of urea in the urea rest causes what to pH in the media?

Answer 22

an increase in pH

Question 23

what is a positive result of a urea test? what does this mean?

Answer 23

pink, meaning the urea is being broken down