single cell prot7111
Transcript of single cell prot7111
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SINGLE CELL PROTEIN
Dead, dry cells of micro organisms e.g., yeast, bacteria, fungi and algae
Properties:
Small doubling time of cells, so greater productivity
Also,
Independent of land and climate
Work on continuous basis
can be genetically controlled
causes less pollution
Factors that impair the usefulness of SCP
a. Non digestible cell wall
b. High nucleic acid content
c. unacceptable coloration
d. disagreeable flavor
SCP treatment
a. Kill the cells
b. Improve digestability
c. Reduce the nucleic acid content
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Due to this property, the productivity of protein production form micro-organisms
is greater than that of traditional proteins
Small doubling time
Efficiency of protein production of several protein sources in 24 hours (16)
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Nutritional value of SCP
Average composition of the main groups of micro-organisms (% dry weight)
Essential amino acid content of the cell protein in comparison with several
reference proteins (grams of amino acid per 100 grams of protein)
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SCP production
General Steps involved in SCP process
Preparation of suitable medium with suitable carbon source Prevention of contamination of medium and plant
production of desired microorganism
separation of microbial biomass and its processing
Media for SCP
a. varies with type of microbe
b. Carbon sources- 2 types
1. Fossil: n alkanes, gaseous hydrocarbons, methanol etc
2. Renewable: Molasses, whey, effluents or other solid substrates
Sterlizationa. By passing media and air through filters
b. by autoclaving
Desired microorganism
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Microbial biomass separation
Fermentor type depends on microbe
Proper aeration is required
Cooling device to remove heat generated during cultivation
production ranges from 4-30gm/lt of microbial biomass at 38C
to 40C and pH 6.8
Microbial biomass harvested by different mechanism
a. Centrifugation e.g., Yeastb. Filtration e.g., filamentous fungi
Drying of biomass
Treatment of biomass for reducing nucleic acid content
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Single Cell Protein
Substrates for SCP production
Gaseous hydrocarbons
Methane: the predominant gas in natural gas
advantage : absence of residual hydrocarbon in the single cell protein produced
from it, unlike the case with liquid hydrocarbons.
Disadvantages: highly inflammable.
Composition of natural gas
Gas %
Methane 82-90
Ethane 4-8
Propane 2-3Others
iso-butane, n-Butane, iso-pentane,
n-Potone, Heptanes plus CO2,
Nitrogen Less than 1%
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Production from methane
Uses continuous cultures and a mixed population of microorganisms.
CH4 + O2 + XH2 CH3OH + H2O + X
Methane oxygenase oxidizes methane to methanol
Channeled into phosphogluconate pathway
CH3OH HCHO HCOOH CO2
Mixed Cultures:-Ensures higher growth rate
-higher yield coefficient
-greater stability
-resistance to contaminations
various members of a four-organism mixture perform different Functions:
the unnamed methane bacterium utilizes methane slowly alone and produces
methanol.
Hyphomicrobium utilizes the methanol,
the other members, Flavobacterium and Acinetobacter (which do not grow on
methane) remove waste products.
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Liquid hydrocarbons
e.g., crude petroleum.
source of microbial vitamins and lipids
Dewaxing of paraffin: removal of higher n-alkanes from crude petroleumfractions
The petroleum hydrocarbons used to grow SCP are diesel oil, gas oil, fuel oil,
n-alkanes (C10 - C30 and C14 C18, C11 C18, C10- C18) n-hexadecane, n-
dodecane.
Not popular because of cost of production
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Alcohols
Methanol is produced
by the oxidation of paraffins in the gas or liquid phase or
by the catalytic reduction by hydrogen of CO and CO2, either singly ormixed.
The catalysts used are mixed zinc and chromium oxides.
Methanol is suitable as a substrate
(a) it is highly soluble in water and this avoids the three-phase (water-
paraffin-cell) transfer problems inherent in the use of paraffins;
(b) the explosion hazard of methanol is minimized in comparison with
methane-oxygen mixtures;
(c) it is readily available in a wide range of hydrocarbon sources ranging from
methane to naphtha;(d) it can be readily purified in a process which avoids the carry over of the
most toxic polycyclic aromatic compounds;
(e) it requires less oxygen than methane for metabolism by micro-organisms
(f) it is not utilized by many organisms
e.g., Over 20 species from the genera Hansenula, (Hansenula polymorpha Pichia,Torulo sis and Candida have been shown to row on methanol
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Waste Products
(i) Plant/wood wastes :
they usually have to be treated in some form such as acid, alkali, sodium chlorate or
liquid ammonia treatment.
The treated material can be digested by a chemical means or by the use of
microorganisms.
Cellulosic agricultural wastes are available in large amounts all over the world;
they are usually of little economic value, and are non-toxic.
(ii) Starch-wastes:
Starch-containing wastes from rice, potatoes etc
relatively easy hydrolyze
e.g., Symba Process developed by the Swedish Sugar Corporation.
In this process two yeasts are used symbiotically:
Endomycopsis fibuligera hydrolyses starch to the sugars glucose and maltose
with alpha and beta amylases. Candida utilis then utilizes these sugars for
growth.
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(iii) Dairy wastes:
Whey e.g.,Saccharomyces fragilis
(iv) Wastes from chemical industries:e.g.,C. lipolutica or Trichosporon cutaneum can be used for SCP production
in oxanone water, a waste mixture of organic acids from the copralactam
used for the manufacture of nylon.
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MICROORGANISMS USED IN SCP PRODUCTION
(a) Absence of pathogenicity and toxicity
(a) Protein quality and content
(c) Digestibility and organoleptic qualities: The organism should not only be
digestible, but it should possess acceptable taste and aroma.
(d)Growth rate: It must grow rapidly in a cheap, easily available medium.
(e) Adaptability to unusual environmental conditions: In order to eliminate
contaminants and hence reduce the cost of production, environmental
conditions which are antagonistic to possible contaminants are oftenadvantageous. Thus, strains which grow at low pH conditions or at high
temperature are beneficial
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