Science

2. Crude Media
• The non-synthetic media with naturally available sources are better suited for
fermentation.
• Crude media is generally used on an industrial scale for fermentation process.
Crude media contains a rough composition of media required for fermentation.
• It gives high yield of product and contains undefined sources of ingredients. Crude
media contains high level of nutrients, vitamins, proteins, growth factors, anti-
foaming agents and precursors.

3. Ingredients of Crude Media
Inorganic nutrients
Crude media contains inorganic salts containing cations and anion along with a
carbon source. Sometimes, fermentation micro-organisms have a specific
requirement of ions like magnesium ions, phosphates or sulphates. These
requirements are fulfilled by addition of these ions to balance the crude media

4. Carbon source
• Simple to complex carbohydrates can be added to media as a source of carbon. We
can add different sugars like mannitol, sorbitol, organic acids, fatty acids, proteins,
peptides we can choose any of these as a source of carbon.
• The selection of carbon source depends upon the availability as well as the cost of
raw material. In most of the fermentation media, crude source of carbon is added.

5. Substrates Used As Carbon Sources:
Molasses:
• Molasses is a byproduct of sugar industry and is one of the cheapest sources of
carbohydrates. Molasses are concentrated syrups or mother liquors recovered at any one
of several steps in sugar refining process with different names depending on the step from
which it is recovered.
• Blaskstrap molasses from sugar cane is normally the cheapest and most used sugar source
for industrial fermentation. Sugar cane molasses (sucrose around 48%) and sugar beet
molasses (sucrose around 33%) are commonly used. Besides being rich in sugar, molasses
also contain nitrogenous substances, vitamins and trace elements.

6. Malt extract:
• Malt extract, an aqueous extract of malted barley, contains about 80%
carbohydrates (glucose, fructose, sucrose, and maltose). Nitrogen compounds
constitute around 4.5% (proteins, peptides, amino acids, purines, pyrimidine’s).
Malt extract are useful carbon sources for the cultivation of filamentous fungi,
yeast and actinomycetes.

7. Sulfite waste liquor:
• It is derived from paper pulping industry after wood for paper manufacture is digested to
cellulose pulp.
• The Sulfurous acid (SO2 in water) and its salts of Ca, Na, Mg, and NH4 used in the
sulfite pulping cause hydrolysis of the more easily hydrolysable components of raw
materials like hemi cellulose It can be used as a dilute fermentation medium for ethanol
production by S.cerivisiae. Waste liquors from coniferous trees contain 2-3 sugar, which
is a mixture of hexoses (80%) and pentoses (20%)..

8. Whey:
• Whey is a byproduct of dairy industry and is produced worldwide.
Most of it is consumed by- humans and animals. Whey is a reasonably
good source of carbon for the production of alcohol, single-cell
protein, vitamin B12, lactic acid and gibberellic acid. Storage of whey
is a limiting factor for its widespread use in fermentation industry.

9. Corn steep liquor:
• This is formed during starch production from corn. Corn steep liquor is rich in
nitrogen (about 4%) and is very efficiently utilized by microorganisms.
Concentrated extracts generally contain about 4%(w/v) nitrogen, including several
amino acids (alanine, valine, methionine, arginine, threonine, glutamate). Its first
use in fermentations was for penicillin production in the 1940s. The extract
composition of the liquor varies depending on the quality of the corn and the
processing conditions.