I-Biomass
1) Baker’s yeast:Baker’s yeast (Saccharomycescervisiae) is used mainly for baking
By Fed batch production to maintain the sugar conc. between
0.5 0.5-1.5 %? 22
2) Single-cell protein (SCP):Torulautilisor Hansenulaanomala(microbial cells)
For use in human and / or animal feed could serve as new sources of proteins and vitamins.
Substrates mainly petrochemicls
SCP is as cheap as Soya meal. But still there is some barriers of use???
3) Microbes as insecticides:Instead of chemical insecticides.
They are more safe compounds that can kill harmful insects by:
a) Direct infection (Bacillus popilliae )
b) Toxin production (Bacillus thuringiensis thuringiensis).
Water soluble toxin = αα-exotoxin
Protein crystal = parasporalparasporalcrystal or crystal δδ-endotoxin endotoxin.
4) Rhizobiumas a fertilizer:
Gram Gram-negative rods
2-3 nitrogen fixing ability
I-Biomass (cont.)
3) Microbes as insecticides:Instead of chemical insecticides.
They are more safe compounds that can kill harmful insects by:
a) Direct infection (Bacillus popilliae )
b) Toxin production (Bacillus thuringiensis thuringiensis).
Water soluble toxin = αα-exotoxin
Protein crystal = parasporalparasporalcrystal or crystal δδ-endotoxin endotoxin.
4) Rhizobiumas a fertilizer:
Gram Gram-negative rods
2-3 nitrogen fixing ability
I-Biomass (cont.)
The production of vinegar (acetic acid):
Empirically: by leaving wine bottles in open air. Commercially vinegar is produced in two steps:CarbohydCarbohyd. .
Alcohol Acetic acidAcetic acid The starting materials may be fruits such as The grapesgrapes(wine(wine--vinegar), oranges, apples or pearsoranges, pears(cider vinegar), (corn or vegetablescorn vegetablessuch as such potatoespotatoes. . SaccharomycescervisiaeAnaerobicAcetobacterAerobic
Alcohol Acetic acidAcetic acid The starting materials may be fruits such as The grapesgrapes(wine(wine--vinegar), oranges, apples or pearsoranges, pears(cider vinegar), (corn or vegetablescorn vegetablessuch as such potatoespotatoes. . SaccharomycescervisiaeAnaerobicAcetobacterAerobic
III-Microbial enzymes
Enzyme stabilization
a) Substrate stabilization:Glucose isomerase, for instance, can be stabilized against heat damage by adding glucose and α-amylase can be stabilized by adding starch.
b)Solvent stabilization: Many solvents stabilize the enzyme when used at low concentration. However, high concentration cause denaturationof enzymes.
C) Cationstabilization:For example calcium ions were found to stabilize the tertiary structure of proteases and α-amylases.
d) Immobilization:Enzymes can also be stabilized by immobilization. In all the stabilization methods listed above the enzymes can be stored softly but since they are still soluble, they can not be recycled after use. On the other hand, immobilized enzymes have the advantage of beingno longer soluble and can be reused or even used continuously.
Immobilized-enzyme technology
Immobilization of enzymes is carried out by:
1. Cross Cross-linking between enzymes: linking with 2 or more
functional groups.
used as polymerizing agent to cross link Glutraldehyde E.g.
several enzymes
2. Bonding enzyme to a carrier (carrier carrier-bond
enzymes): may be by:
Adsorption: cause least damage but the bond is weak
and enzymes can easily eluted from the carrier
Ionic bonding: Weak bonding
Covalent bonding: Strong bonding and most widely used
Immobilized-enzyme technology
Immobilized enzymes within cells
Advantage:
1. Shorter recovery and purification times (i.e. low costs)
2. Cofactors, required for enzyme activity may be already present within the cells
3. Multi-enzyme reactions can be carried out.
Disadvantages: Undesirable side reactions by other enzymes may occur.
but difficult and expensive