Lab Quiz 2

Front 1

Which organisms that you tested could not grow on the glucose mineral medium, and which could? Why did certain ones grow?

Back 1

S.aureus (requires growth factor)

Which organisms that you tested could grow on it?

B.thuringeinsis- slowly, because it's using energy to make all growth factors

E.Coli- grew slowly

P.aeruginosa- grew faster because it makes all of its growth factors

Front 2

Which organisms that you tested do not require any growth factors?

Back 2

E. Coli, Pseudomonas and Enterobacter

Front 3

.Of the organisms that could grow on both TSA and glucose mineral agar, did some organisms grow better on the TSA than on the glucose mineral? Why?

Back 3

Organisms can grow better on a complex medium such as TSA because it contains many preformed molecules that do not need to be synthesized

Front 4

In general, EMB agar selects for what kinds of organisms?

Back 4

Coliforms

Front 5

Which organisms could grow on the EMB agar? How did they appear, and what did they do? Which can not grow and why?

Back 5

E.coli (metallic green) ++ (fermented lactose)

E.aerogenes (pink) ++ (lactose fermenter)

P.aeroginosa (white)++

S epi. Can not, inhibited by emb and it is gram positive

Front 6

Which organisms could ferment lactose? Could they ferment lactose, and if so how much?

Back 6

E.coli (lots of acidic products)

E.aero (smaller amounts of acidic products)

Front 7

What organisms could grow on the TSA?

Back 7

All

Front 8

Define complex medium

Back 8

The exact amounts of chemical components and their composition are unknown because it is made of extracts.

Front 9

Define chemically defined medium.

Back 9

A synthetic medium composed of inorganic salts and usually carbon source such as glucose.

Front 10

What type of medium is Glucose Mineral Agar?

Back 10

Chemically defined, selective. Only organisms that can make all their componenets from glucose and inorganic salts can grow on it.

Front 11

What is TSA?

Back 11

Rich, complex medium, from protein digests and Soy.

Differential or non-selective

Organisms that require vitamins or other growth factors can grow on it.

Front 12

EMB?

Back 12

Selective Medium Permits growth of Gram negative enteric rods, inhibits growth of Gram positive. It is also differential because it contains sugar lactose, Organisms that can ferment lactose appear different than those that don't. Lactose fermentation produces acidic products which causes ph to decreas, changes color

Front 13

Different Medium?

Back 13

MEdium permitting certain organisms to be distinguished from others by the appearance of their colonies.

Front 14

MSA?

Back 14

Differential purpose: The MSA contains mannitol and the ph indicator phenol red.

Organisms thag ferment manitol will appear different from those that dont. Example: When S aureus ferments the mannitol, the fermentation products are acidic, which changes the color of the ph indicator to yellow.

Selective purpose: The 7.5% NaCl in the MSA inhibits the growth of many types of bacteria (i.e., non-salt tolerant). Only salt tolerant bacteria (e.g., Staphylococcus sp, Micrococcus sp) can grow.

Front 15

What organisms could grow on the MSA, and which couldn't?

Which could ferment manitol, and which couldn't?

Why couldn't certain ones grow?

Back 15

S.aureus could grow, and fermentated manitol S.epidermididis could grow, and did not ferment manitol

B.thur and e coli did not grow, because they cannot tolerate salt

Front 16

.Would you expect an obligate anaerobe to grow on a slant or plate incubated aerobically? Why?

Back 16

No, cannot grow in the presence of oxygen.

Front 17

Which kind of organisms can grow aerobically on slants or at the top of thioglycollate tubes?

Back 17

Aerobes and facultative

Front 18

Why did you boil the agar deeps longer than it took to melt the agar?

Back 18

To completely drive out the oxygen

Front 19

.If air can diffuse into agar and broth, how were the obligate anaerobes grown in the broth before class?

Back 19

Probably an anaerobe jar

Front 20

What is Clostridium sporogenis? How did it grow, what is it classified as?

Back 20

Obligate Anaerobe

Grew throughout agar but not on top.

This is because of the gas. Gas is a bi-product of fermentation

Front 21

What is M. luteus? How did it grow, what is it classified as?

Back 21

Only grew at the top, grew on the slant. It is an obligate aerobe.

Front 22

Which of the three organisms you inoculated can grow throughout agar deep and on top?

Back 22

E.Coli (it is faculative) Produced gaseous product

Front 23

What kind of organism would you expect to grow on or in both types of media?

Back 23

Facultative anaerobes.

Front 24

What is Micrococcus Luteus?

Back 24

Obligate aerobe

Growth only on top.

Front 25

Which chemical reaction produced the color yellow?

Back 25

The action of B-galactosidase on ONPG

Front 26

.In the catabolite repression exercise, did the Bacillus have the capacity to synthesize amylase?

Back 26

The bacillus could synthesize amylase because there was a zone of clearing when testing for starch with iodine indicating there no longer was any starch present

Front 27

Did you observe catabolic repression when glucose was added to the starch?

Back 27

Yes, because the zone of clearing was not observed in the presence of glucose and therefore the starch was not broken down and utilized

Front 28

What results would you expect if amylase were a constructive enzyme?

Back 28

The starch would then always be degraded, even in the presence of glucose.

Front 29

Did you observe catabolic repression when glucose was added to the starch?

Back 29

Yes, because the zone of clearing was not observed in the presence of glucose and therefore the starch was not broken down and utilized.

Amylase was repressed

Front 30

.What results would you expect if B-galactosidase were a constructive enzyme?

Back 30

All the tubes would be yellow is B-galac were constructive

Front 31

What is B-galactosidase?

Back 31

An enzyme that Breaks down lactose (disacharide) into monosacharides- glucose and galactose --> they are then catabolized for energy

Front 32

What does ONPG tell?

Back 32

Whether you have B-gal present or not

Front 33

What does the presence of glucose determine?

Back 33

Absence of lactose, therefore, no B-gal expression.

It would be insufficient for the cell to synthesize b gal if lactose were not present, therefore only the presence of lactose induces the synthesis of b gal.

Front 34

.Why would a cell use glucose?

Back 34

Because the cell would use less energy, since glucose can enter the glycolytic pathway. Starch must first be cleaved with amylase and other enzymnes that cost the cell energy.

Front 35

What does the presence of glucose determine?

Back 35

Absence of lactose, therefore, no B-gal expression

Front 36

How do you test for b galactosidase?

Back 36

Add ONPG. if it is present, it will cleave ONPG and form a yellow dye. So positive test for b gal is yellow color in presence of ONPG