Genetic improvement of microbial strains

Genetic improvement of microbial strains

1. Genetic Improvement of microbial strains By, Abhinava J V University of Agricultural Sciences, Dharwad

2. Need of Genetic Improvement For increase in yield of the desired product, medium and growth conditions should be optimized. Medium and growth optimization is having limited effect on increase in the product due to organism’s maximum ability to synthesize the product which is controlled by its genome. Thus if one want to increase the product then one should modify the genome. This is called as genetic improvement of that organisms.

3. Genetic Improvement can be achieved by:

4. Mutation and Selection In nature, mutations (changes in the chromosome of an organism) occur spontaneously at very low rates (one mutational event in every 10 6 to 10 7 cells per generation. The mutation rate can be dramatically increased by exposure of microorganisms to mutagenic agents, such as ultraviolet light or various chemicals, which induce changes in the deoxyribonucleic acid (DNA) of host cells.

5. Types of mutagens

6. Physical Mutagens

7. Chemical Mutagens

8. Biological Mutagens

9. Natural Gene Transfer Methods

10. Transduction Transduction involves genetic exchange mediated by a bacterial virus ( bacteriophage ).

11. Conjugation Conjugation, or bacterial mating, is a natural gene transfer system that requires close physical contact between donors and recipients and is responsible for the dissemination of plasmids in nature.

12. Transformation Certain microorganisms are able to take up naked DNA present in the surrounding medium. This process is called transformation and this gene transfer process is limited to strains that are naturally competent.

13. Electroporation This technique involving the application of high-voltage electric pulses of short duration to induce the formation of transient pores in cell walls and membranes. Under appropriate conditions, DNA present in the surrounding medium may enter through the pores. This is the physical method to make the cell competent.

14. Genetic Engineering Genetic engineering is revolutionizing the science of strain improvement and is destined to have a major impact on the food fermentation industry. Genes code for desirable traits can be used from any living organism (plant, animal, microbe or virus). Engineered bacteria, yeast, and molds could also be used for the production of other products, including food additives and ingredients, processing aids such as enzymes, and pharmaceuticals.

15. Metabolic engineering Metabolic engineering is generally defined as the redirection of one or more enzymatic reactions to produce new compounds in an organism, improve the production of existing compounds, or mediate the degradation of compounds. Metabolic engineering is the use of genetic engineering to modify the metabolism of an organism.

16. Metabolic engineering requires the basic molecular biological technologies such as cloning, promoter analysis, protein targeting, plant transformation, biochemical genetics, and other areas of plant biology. The most successful metabolic engineering approach is Golden rice, production of Vitamin A in rice by introducing new pathways.

17. Mode

18. Process

19. Application