Transcript Bean recipe

TYPE OF ENERGY SOURCES AND
CHARACTERISTIC FOR A LARGE SCALE
MEDIA
INTRODUCTION TO THE
MEDIA OF FERMENTATION
•All
micro-organisms require water, sources of energy,
carbon, nitrogen, mineral element and vitamin plus
oxygen in their growth medium.
•On
a small scale, it is simple to device a medium
containing pure compounds, but the resulting
medium although satisfy the growth, may be
unsuitable for use in a large scale process.
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On a large scale one must use sources of cheap
nutrient to create a medium which will meet as many
as possible of the following criteria:
1.
2.
3.
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5.
6.
It will produce a maximum yield of product at
biomass per gram of substrate used.
It will produce a maximum concentration of product
or biomass.
It will permit the maximum rate of product
formation.
It will be the minimum yield of undesired product.
It will be cheap and of a consistent quality and is
readily available throughout the year.
It will cause minimal problem in other aspects of
production and agitation, extraction, purification
and waste treatment.
Use of molasses, cereal grain, glucose, sucrose and
lactose as carbon sources
and ammonium salts, urea, nitrates, soya bean meal,
slaughter-house waste and fermentation residues as
nitrogen source
have tended to meet the above criteria for production
media.
The medium selected will affect the design of the
fermenter to be used.
 A laboratory medium may not ideal in a large
fermenter with a low gas-transfer pattern.
 Media with a high viscosity will also need a higher
power input for effective stirring.
 Besides the requirement for growth and product
formation, medium may also influence pH variation,
foam formation, oxidation-reduction potential and the
morphological form of the organisms.
 It may also be necessary to provide precursors or
metabolic inhibitors.
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Typical Media
MEDIUM FORMULATION
Medium
formulation is an essential stage in the
design of
~successful laboratory experiments
~pilot-scale development
~manufacturing processes
The
constituents of a medium must satisfy
~the elemental requirements for cell biomass and
metabolite production
~must be an adequate supply of energy for
biosynthesis and cell maintenance
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Equation based on the stoichiometry for growth and
product formation.
Carbon and energy source + nitrogen source + other
requirements
cell biomass + products + CO2
+ H2O + heat
This equation should be expressed in quantitative terms,
which is economical design of media if component wastage
is to be minimal.
It should be possible to calculate
~the minimal quantities of nutrients which will be needed
to produce a specific amount of biomass
~the substrate concentration in order to produce required
product yield
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A knowledge of the elemental composition of a named
micro-organisms, which should include the content of
C, H, O, N, S, P, Mg and K, is required in the solution
of the elemantal balance equation.
Elemental composition of micro-organism in medium.
 From
Table 4.2:
~the absolute minimum quantities that needed to
include in an initial medium recipe are N, S, P,
Mg and K.
~trace elements may also be needed in smaller
quantities such as Fe, Zn, Cu, Mn, Co, Mo, B.
 An
analysis of relative concentrations of
individual elements in bacterial cells shows
~ some nutrients are frequently added in
substantial excess of that required e.g. P, K
~others are often near limiting values, e.g. Zn, Cu.
 Some
micro-organisms cannot synthesize
specific nutrients such as amino acid, vitamins
or nucleotides.
 Once
a specific growth factor has been
identified it can be incorporated into a medium
in adequate amounts as a pure compound or as
a component of a complex mixture.
 The
role of carbon substrate involved in
~biosynthesis
~energy generation

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The carbon requirement under aerobic condition may
be estimated from the cellular yield coefficient (Y)
which s defined as:
= Quantity of cell dry matter produced
Quantity of carbon substrate utilized
Some value are given in Table 4.3
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Thus, for bacteria
Y of glucose = 0.5 = 0.5 g cells 1.0 g glucose-1
= the quantity of glucose neededto obtain 30 g dm-3
= 30/0.5
= 60 g dm-3 glucose
thus, medium would also need to contain
approximately
3.0 g dm-3N, 1.0 g dm-3P and 0.3 g dm-3S.
An adequate supply of the carbon source is also
essential for a product forming fermentation process.
In a critical study, analyses are made to determine how
the observed conversion of the carbon source to the
product compares with the theoretical maximum yield.
 Cooney
(1979) has calculated theoretical yield
for penicillin G biosynthesis on the basis of
material and energy balances using a
biosynthetic pathway based on reaction
stoichiometry.
 The
stoichiometry for the overall synthesis is:
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Solution of this equation yields:
In this instance it was calculated that the theoretical
yield was 1.1 g penicillin G g-1 glucose.
The other major nutrient which will be required is
oxygen which will be provided by aerating the culture.
The design of medium will influence the oxygen
demand of a culture in that the more reduced carbon
sources will result in higher oxygen demand.
Water
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Major component of all fermentation media
Factors need to be considered
 pH
 Dissolve salt
 Effluent contamination
Mineral water content of water is very important in
brewing, and most critical in the mashing process, and
historically influenced the siting of breweries and the
type of beer produced.
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Nowadays, the water may be treated by deionization
or other techniques and salts added, or pH adjusted, to
favour different beers so that breweries are not so
depend on the local water sources.
In large continuous-culture SCP plants it is common
practice to recycle the water streams.
It may even be possible to reuse all the water in the
fermenter fed with appropriate adjustment of nutrient
levels.
Energy Sources
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Energy for growth comes from either the oxidation of
medium components or from light.
Most industrial micro-organisms are chemoorganotrophs, therefore the commonest sources of
energy will be the carbon source such as
carbohydrates, lipids and proteins.
Some micro-organisms can use methane or methanol
as carbon and energy sources.
CARBON SOURCE
Carbon requirement for the medium is
normally provided by:
•
Nutrient
Raw material
Sucrose
Sugarcane, sugar beet molasses
Glucose
Corn sugar, starch, cellulose
Lactose
Milk whey
Fats
Vegetable oil
Starch
Maize grains, cereals, potatoes and
casava
Hydrocarbons Petroleum fractions
CONT..
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i.
ii.
iii.
Barley grains
It may be partially germinated and heat
treated to give material known as malt.
Malt:
Contains a variety of sugar besides starch
Is the main substrate for brewing in many
countries.
Malt extract may also be prepared from malted
grain.
Sucrose
 Obtained from sugar cane and sugar beet
 Commonly used in fermentation media in very impure
form as beet or cane molasses
Lactose and crude lactose(milk whey)
Now is extremely limited in media formulation since
the introduction of continuous-feeding process.
 Whey is used as a substrate for biomass production
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Vegetable oil
 Example:
olive, maize, cotton seed, linseed,
soya bean, etc.
 Source of carbon : oleic, linoleic and linolenic
acid.
 As an antifoam in association with a surface
active agent.
Other carbon sources:
 Example:
i.
Alcohols
ii.
Simple organic acids with alkanes
-more expensive than equivalent quantities of crude
carbohydrate.
 These compound can be obtained in a pure form
-by simplify subsequent recovery and purification
process
 For methane, methanol and n-alkalines:
- Utilized as a substrates for biomass production.
VITAMINS

Biotin
also known as vitamin H or B7

chemical formula :

C10 H16 N 2O3 S