FERMENTATION AND FERMENTOR

Dr. K. P. Narkhede

Dept. of Microbiology,

M. J. College, Jalgaon

nketan@yahoo.com

11.Aug.2009

FERMENTAION

Fermentation refers to any process by which

large organic molecules are broken down to

simpler molecules as the result of the action of

microorganisms.

e.g. Conversion of sugars and starches to alcohol

by enzymes in yeast - Alcoholic or Ethanolic

fermentation

French chemist Louis Pasteur was the first

zymologist,

EXAMPLES OF FERMENTATION

Alcoholic beverages from - grapes, berries, corn, rice, wheat,

honey, potatoes, barley, hops, cactus juice, cassava roots and other

plant materials.

Batter for bread is mixed with a small amount of sugar and yeast

is added, during the rising period, sugar is fermented by enzymes

in the yeast, with the formation of carbon dioxide gas.

Production of olives, cucumber pickles, and sauerkraut from the

raw olives, cucumbers, and cabbage, respectively.

Antibiotics and other drugs can be prepared by fermentation -

plant steroid known as diosgenin. Enzymes provided by the mold

Rhizopus nigricans.

Production of ethyl alcohol for use in gasohol. Mixture of about

90% gasoline and 10% alcohol.

Treatment of wastewater - activated sludge process, aerobic

bacteria are used to ferment organic material in wastewater.

FERMENTATION MEDIA

The growth medium used for the cultivation of production strain and subsequent production of product is called as production medium.

Composition

Provide essential nutrients for–growth of organism, energy production, building of cell substance, biosynthesis of product.

Nutritionally rich so as to allow the luxury metabolism of organism.

Excess amount of nutrients and metabolize it by using different pathways. This creates ‘metabolic stress’ on organism

Media usually contain 70-90% water

Minerals, metals and other substances that may be required in minute quantities

SYNTHETIC MEDIA VS CRUDE

MEDIA

Synthetic media

All the constituents are specifically defined and known compounds

Constituent is relatively pure and the exact amounts ---> allows to make variation

No foaming problem is observed for synthetic media.

Reproducibility of result is possible.

Recovery and purification of product is easy.

Expensive and often low yielding.

Crud media

Give higher yield of fermentation product

Supply precursors for biosynthesis of products

Provides excess of nutrients and growth factors

e.g. medium with soybean meal, black strap molasses, corn-steep liquor

RAW MATERIALS

Provide a cheaper C, N and energy source for the

growth of organism.

Economical - Mostly agricultural products

Produced in large quantities.

If exposed they cause pollution hazards and hence, it is

better to use them as a raw material.

Contain large amount of potentially useable proteins &

carbohydrates.

Caloric values of waste are recoverable.

Most of them are renewable and hence there is no

shortage of fermentable substrate.

Low cost.

TYPES OF RAW MATERIALS

Saccharine - carbon

Molasses : Black strap molasses (52% total sugar )

High taste molasses (70-75% sugar)

Beet molasses

Corn molasses (60% sugar and also high salt content).

Fruit juices 17% w/w sugar, 1% acid

Whey Lactose 4.62-5.01

Starchy

cereals ( e.g. wheat, rice, maize etc)

Roots and tubers e.g. potato, tapioca etc.

Starch require pretreatment - enzymatic or chemical

….cont.

TYPES OF RAW MATERIALS

Cellulosic

Sulfite waste liquor

liquor from pulp-paper industry (20% are sugar)

Wood molasses

Rice straw.

Nitrogenous compounds

Corn steep liquor

by- product obtained during manufacture of starch and

other products from corn.

Lactic acids, glucose and other reducing sugars , salts,

vitamins and precursors

….cont.

BIOREACTOR

It is a reactor vessel or container which is used

for actual fermentation process

Size of fermenter Laboratory fermenter: 1-2 lit to 12-15 lit

Pilot plant fermenter: 25 – 100 gal to 1000gal.They are used for scale

up studies.

Industrial scale fermenter: 5000 – 10,000 gal to 2, 50,000 – 5, 00,000

gal.

316 stainless steel, borosilicate glass, iron, copper

In selection of a fermenter following points should be considered:

The life span of the vessel should be more

Not be affected by the pH or temperature changes during the fermentation.

No effect of end-product on the vessel e.g. lactic acid.

Vessel should not produce any metal ions or toxic ions

Not show corrosion

Able to withstand the pressure of large volume of medium.

Inoculum addition Fermenter shows two part head and base, Opening provided with

head

Sterile medium addition Sterilized medium added , Sterilized after addition

….cont.

Temperature control

pH control

Aeration: Sparger - 1/32 to 1/64 inches in diameter.

Simple hollow tube with only one hole

Simple tube with many holes and

Ring sparger.

Agitation Impellar blades and impellar shaft -attached to electric motor

Baffles Continuous agitation :

Vortex formation

The segments of medium and microbial cells remain in relatively same position in the moving liquid

Decreased aeration due to little splashing at the liquid surface.

Sparger

Agitator

….cont.

Antifoam agents

Aeration and agitation of a liquid medium cause the

production of foam

If uncontrolled

Possibility of contamination, Loss of medium. Affect aeration

Mechanical defoamers OR Antifoaming agents

Inert antifoams: Various silicone compounds

Antifoams made from crude organic materials (lard oil,

corn oil, soybean oil )

Working volume - 3/4th

Butterfly valve - Leaky to expel the gases

accumulated in head-space

Sampling - At the bottom of the fermenter

….cont.

TYPES OF FERMENTATION

Batch fermentation

Continuous fermentation

Single stage , Single stage recycle

Multiple-stage continuous fermentation

Dual or multiple fermentations

Surface fermentation

Submerged fermentation

Solid state fermentation

FOR LABORATORY RESEARCH

Chemostat

Turbidostat

Air lift

Tower

Air lift Cylindro conical

THANK YOU ….

Any questions ……