Question

In: Biology

1) How are phenol red broth test, urea test and lipase test connected to one another?...

1) How are phenol red broth test, urea test and lipase test connected to one another?

a) they use the same enzyme                         b)they have the same products

c) they use the same indicator                      d) they have the same color of a positive result

2) I am a microorganism that causes skin infections. Yes, I can live at higher salt concentration almost like the perfect Staphylococcus aureus, but due to the nature of my ecological niche, I also must be able to digest .................

When I digest that important chemical substance, I will turn the indicator in the test, which is called

Lipid hydrolysis yellow.

3) I am an inhibitor of an enzyme that plays an important role in the Krebs cycle. I am a part of a specialized microbiological test that uses bromthymol blue as an indicator and generates blue color as positive test result.

My name is Malonate Test

the name of the substance that I am a structural analog of is called succinate

the name of the enzyme that I bother to be an inhibitor of is succinate dehydrogenase

4) The name of the other microbiological test that uses the same indicator as the indicator used in the test named after me is Pyruvate dehydrogenase test/pyruvate carboxylase test/kreb’s cycle/indicator as succinate dehydrogenase

And an organism positive for the production of casease is capable for digesting:

a) lipids   b) carbohydrates   c) DNA   d) casein

Solutions

Expert Solution

Question 1

Phenol red is as indicator. The indicator is yellow in acidic medium and pink in alkaline medium. Phenol red broth test is a differential medium which identifies enteric bacteria. This broth uses phenol red as indicator. Urease broth is a differential medium that hydrolyzes urea to ammonia and carbon dioxide. This test uses phenol red which changes from yellow to pink as ammonia provides an alkaline medium. Lipase test is used for screening lipolytic organisms which also uses phenol red as an indicator dye. Thus, phenol red broth, urea test and lipase test are connected since (c.) they all use the same indicator phenol red.

Question 2

Lipids are macromolecules that are important for respiration processess. Lipids such as triglycerides are hydrolyzed by enzymes lipases (esterases) to form glycerol and fatty acids. In the lipase test, the triglyceride tributyrin is used as the lipid substrate and phenol red as an indicator. If the microorganism can hydrolyze triglyceride tributyrin, the end product fatty acids are released in the medium making it acidic to produce a yellow color. Therefore the organism digests triglycerides and the test is lipid hydrolysis test.

Question 3

Malonate is an inhibitor of the enzyme succinate dehydrogenase and is a structural analog is succinate. Succinate dehydrogenase is an enzyme in the Krebs cycle that converts succinate to fumarate. The malonate test is used as a differential medium to identify the family of Enterobacteriaceae. This test is done to identify if an organism can utilize sodium malonate as carbon source and ammonium sulfate as its nitrogen source. The medium has sodium malonate, ammonium sulfate and bromothymol blue. If an organism utilizes sodium malonate and ammonium sulfate, it forms sodium hydroxide which makes the medium alkaline. The indicator in alkaline medium turns prussian blue from its original green color (acidic). Therefore the structural analog is succinate, enzyme is succinate dehydrogenase and the test is malonate test.

Question 4

Casein forms an opaque suspension of milk that makes the milk appear white.Casease is an enzyme that allows the organisms that to break down casein into smaller peptides, and amino acids that can cross the cell membrane and be utilized by the organism. Therefore an organism which has casease digests casein.


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