Acetic Acid
Fermentation
Presented by : Fiza Sikandar
Roll no 19
Introduction:
• Acetic Acid is also known as Ethanoic acid .
• Colorless Liquid and Organic Compound.
• It is the second simples Carboxylic Acid.
• Vinger contains 4-8% acetic acid by volume apart from water
and other trace elements.
• Vinger is also known as Dilute Acetic Acid.
Bacteria carrying out Acetic
Acid Fermentation
• The group of Gram-negative bacteria capable of oxidizing ethanol to acetic
acid is called acetic acid bacteria (AAB).
• Acetic acid fermentation is generally carried out Two bacterial Genera:
 Gluconobacter sp
Acteobacter.aceti
• Both species are obligate aerobs
• They oxidize sugars, sugar alcohols and ethanol to ethanoic acid.
Acetic Acid
Production
• Substrates: Ethanol
(Preferbally small amount)
• Products : Acetic Acid
• Bacteria: Acetobacter.aceti ,
Gluconobacter
Mechanism of production:
• Ethanol
Ethanol/Alcohol dehydrogenase
Acetaldehyde
Hydrate
Acetaldehyde Hydrate
Acetic Acid
Acetaldehyde dehydrate
Gluconobacter. suboxydans
• Lacks the functional TCA cycle although all enzymes except succinate
dehydrogenase are present.
• It cannot ferment glucose or any other carbohydrate as Entner-Doudoroff
and EMP pathways are not present.
• Modified pentose cycle is used for metabolism of glucose under Aerobic
Conditions.
• Gluconobacter undergoes a very fast process
• It caries out partial oxidation of ethanol
Acetobacter.aceti
• It has the characteristic TCA cycle.
• The acetyl phosphate from cleavage of C2 and C3 cleavage of
pentose is oxidized to CO2 and energy is generated via oxidative
phosphorylation.
• It undergoes Full oxidation
• Also reffered as "Over Oxidizer"
• Appropriate conditions are required.
Step 1:
Alcohol is produced by yeast fermentation
(converting glucose to CO2 and alcohol).
Step 2 :
Acetobacter.aceti converts ethanol to acetic
acid
This process requires appropriate conditions
for maximum yield
Commercial
Preparation
Modified
Pentose Cycle
for Acetobacter
and
Gluconobacter
Industrial Applications
• The acetic acid bacteria (AAB) have important roles in food and
beverage production, as well as in the bioproduction of industrial
chemicals
• The AAB are also involved in spoilage of beer, wine, and cider
among fermentation
• Some of the biggest benefits of Acetic Acids is that it helps control
blood sugar, lowers blood pressure and inflammation
Applications :
• Acetic acid is more sour and more pungent than lactic acid.
• These bacteria are also used in the production of other metabolic products, for
example, gluconic acid, L-sorbose and bacterial cellulose, with potential applications
in the food and biomedical industries.
• Kombucha is a traditional beverage that is made by fermenting sugary tea with a
symbiotic culture of acidophilic yeasts and AAB embedded in a microbial cellulose
layer called tea fungus. AAB oxidises the produced ethanol to acetic acid
• The main AAB strains found in kombucha are A. aceti.
Applications:
• Gluconic acid occurs naturally in fruits, plants and other foods, such
as wine, vinegar and honey
• G. oxydans, used for the industrial production of gluconic acid
• AAB, particularly strains of the genus Gluconobacter that possess
an enormous oxidative capacity, can be used for oxidative
conversion of D-sorbitol to L-sorbose, an important intermediate in
the industrial production of L-ascorbic acid (vitamin C)
Thankyou !