single cell prot7111

8/7/2019 single cell prot7111

1/19


2/19

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


3/19

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)


4/19

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)


5/19

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


6/19

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


7/19

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%


8/19

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.


9/19


10/19

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


11/19

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


12/19


13/19

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.


14/19

(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.


15/19

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


16/19


17/19


18/19


19/19

single cell prot7111

Documents

Transcript of single cell prot7111