Lecture 12 Strain improvment Flashcards
Give two types of strain improvment.
Mutagenisis & screening
Metabolic engineering
What is the strain improvment process?
The strain is isoloated, screened, improved and screende again untill good enough to be preserved.
Which are substrate improvment targets?
Substrate range, tolerance, yield, product concentartion and new products.
How can new micro-organisms be found?
- Isolation and screening
- Classical strain improvement
- Introduction of targetted genetic alterations
Dufference between stain isolation from nature compared to strain collection.
Strain collections • Few microorganisms available • Well known • Cheap • The best strains are not available
Nature • Very many types can be explored • Expensive • Time consuming • Special properties
Describe method for classical strain improvment.
- Mutation
- Recombination/Breeding/Mating
- Protoplast fusion
- Evolutionary engineering
- The methods are generally used in combination to develop high producing strains.
Example of physical mutagenes
g Rays, X Rays, UV Rays and High Energy e
Example of chemical mutagnes
Alkylating agents, HNO2 Deaminating agents and Base analogs.
What is evolutionary engineering?
Experimental improvement of cellular
properties exploiting genetic variation in
large microbial populations and selection
through under a controlled selection
pressure for predetermined functions.
What controlles a chemostat, turbidostat, auxostat and a productostat?
CHEMOSTAT: steady state is controlled by keeping volume or weigh constant with constant flow in and out
TURBIDOSTAT: controlled by keeping cell concentration constant (pump is controlled by an OD probe)
AUXOSTAT: controlled by keeping pH constant
(pump is controlled by a pH probe)
PRODUCTOSTAT: controlled by keeping the on centration of an on-line measured product constant (pump is controlled by an online sensor)
What is proplast fusion
Protoplasts are cells devoid of their cell walls
• Cell fusion follwed by fusion of the nuclei may occur
between protoplast of different strains
• Regeneration of cell wall occurs
• Protoplast fusion products can be used for further
studies
What is metabolic engineering?
Improvement of cellular activities by manipulation of enzymatic, transport and regulatory functions of the cell with the use of recombinant DNA technology.
