Alchohol Fermentation

8/11/2019 Alchohol Fermentation

1/18

Anaerobic Respiration: AlcoholicFermentation of Saccharomyces

cerevisiae

Repotente, Elmer Casley

Rodriguez, Princess Vanessa

Sevilla, Emmanuel Ruthe

Tan, Keana Dehnielle

Trinidad, Kyle Celine


2/18

Saccharomyces cerevisiae

Objectives

Describe alcoholic fermentation, naming reactants

and products

To demonstrate the end products CO2and ethanol

To observe the difference of aerobic and anaerobicrespiration

To explain the process of aerobic and anaerobic

respiration


3/18


4/18


5/18

Fermentation tube

A is unclear and

cloudy.


6/18

The yeast settled at thebottom of tube B after 2

days of adding the live

yeast suspension. There are

also bubbles formed at the

arm of the fermentation

tube


7/18

The microorganism has undergone aerobicrespiration using the dissolved oxygen to buildup its cell population

Aerobic respiration requires oxygen as theterminal electron acceptor. Since there is

presence of oxygen, it breaks down glucoseaerobically following the metabolic sequenceof glycolysis, intermediate reactions, Krebscycle, and electron transport system. Withthe energy released, carbon dioxide and waterbecome the by-products of the reaction.


8/18

Tube C

Remove the cotton plug and smell the content

To prove the presence of CO2, prepare andnumber two test tubes in a test tube rack

Test Tube 1: Transfer a pipetteful of

fermentation medium from tube C

Add one drop of phenol redsolution

Test Tube 2: Place a similar pipetteful ofsimilar distilled water.

Add one drop of phenol redsolution

Tube CThe bubbles

formed at the

arm of the tubeis reduced. A

precipitation

has formed andsettled in the

tube.


9/18

5 days after adding the live yeast suspension

in the solvent consisting of 50 mL 10%

glucose, 30 mL 2% peptone, and 0.5% yeastextract, the organism used the excess glucose

anaerobically.

Anaerobic respiration is a respiration without

oxygen and it is often called fermentation.

Without oxygen, only glycolysis takes

place.

Glucose is metabolized to pyruvate (end

product of glycolysis) which will beconverted into two waste products:


10/18

TUBE C

There is a sour unpleasant odor thatstank as soon as we remove thecotton in tube C.

The sour smell of is the odor given offby yeast fermentation, specificallyby the


11/18

Presence of CO2from tube C:

Phenol red is a pH indicator; it is

and

Color with Phenol

Red

pH

Tube 1 Yellow Acidic

Tube 2 Red Basic


12/18

The first tube exhibited a yellow color which

only means that it is acidic. It is because of the CO2of aerobic respiration

and water producing carbonic acid.

The pyruvate is first converted toacetaldehyde, and the NADH (Nicotinamide-adenine dinucleotide ) reacts with that,forming ethanol (ethyl alcohol).

The second tube showed a red orangesolution which is interpreted as basic.

To prove the presence of

ethanol, you will do theiodoform test.

Test Tube 1: 2.5 mLdistilled water

Test Tube 2: 1.25 mLdistilled water and

1.25% ethanol

2.5 mL medium fromfermentation tube C


13/18

Tube Sample Iodoform Result

1 2.5 mL distilled

water

-

2 1.25 mL distilledwater and 1.25 %

ethanol

-

3 2.5 mL medium

from

fermentation

tube C

+

Iodoform

testTEST TUBE 3

- POSITIVE


14/18

Yeast Cells under LPO and HPO


15/18

The presence or absence of O2 makes a

difference

The fate of pyruvatedepends on oxygen availability:

+ O2 - O2

Aerobic respiration Fermentation


16/18

CONCLUSION

In aerobic respiration, the end products arecarbon dioxide and water. In anaerobic

respiration, the end products are ethyl alcohol

or lactic acid, and carbon dioxide. The presence of Carbon dioxide as a by-

product of respiration is proven by the yellow

color of the phenol-red treated sample.

The presence of ethanol is proven by the

iodoform formed in the sample taken.


17/18

When the oxygen became low, the yeast,

switched from cellular respiration to alcoholic

fermentation.


18/18

References:

Vasquez, R.D., et al. (2013). Laboratory

Manual for Pharmaceutical Botany. Espaa,Manila: University of Santo Tomas Press.

Mauseth, J.D. (2013). Botany: An Introduction

to Plant Biology. Quezon City: Mind MoverPublishing House, Inc.

http://www.anaerobicrespiration.net/general/aanerobic-respiration-fermentation/

http://hyperphysics.phy-astr.gsu.edu/hbase/organic/pyruvate.html
http://www.anaerobicrespiration.net/general/aanerobic-respiration-fermentation/http://www.anaerobicrespiration.net/general/aanerobic-respiration-fermentation/http://www.anaerobicrespiration.net/general/aanerobic-respiration-fermentation/http://www.anaerobicrespiration.net/general/aanerobic-respiration-fermentation/http://www.anaerobicrespiration.net/general/aanerobic-respiration-fermentation/http://www.anaerobicrespiration.net/general/aanerobic-respiration-fermentation/http://www.anaerobicrespiration.net/general/aanerobic-respiration-fermentation/http://www.anaerobicrespiration.net/general/aanerobic-respiration-fermentation/

Documents

Alchohol Fermentation