Strain improvement technique (exam point of view)
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Strain improvement involves developing industrial strains that tolerate environmental conditions and produce desired metabolites in larger quantities than wild type strains, achieved through genetic changes. Key methods include mutation and mutant selection, protoplast fusion, and recombinant DNA techniques, which enhance fermentation efficiency and product yield. Examples of successful improved strains include penicillin-producing strains developed via mutagenesis and protoplast fusion.
Strain improvement technique (exam point of view)
- 1. STRAIN IMPROVEMENT TECHNIQUE (EXAM POINT OF VIEW) Sijo.A
- 2. STRAIN IMPROVEMENT The development of industrial strains, that can tolerate cultural environment and produces the desired metabolite in large amount from wild type strain is called strain improvement. The rate of production is controlled by genome of an organism. Hence the rate of production can be increased by inducing necessory changes in genome of the organism. Hence it is also called genetic improvement of microbial strain.
- 3. The improved strain possess the following characteristics: 1) Shorter time of fermentation 2) Capable of metabolizing low cost substrates. 3) Reduced oxygen demand 4) Decreased foam formation 5) Non-production of undesirable compounds. 6) Tolerance to high concentration of carbon and nitrogen sources. 7) Resistant to infection of bacteriophages. Strain improvement can be performed in following ways. 1. Mutation and mutant selection 2. Protoplast fusion 3. Recombinant DNA technique
- 4. MUTATION AND MUTANT SELECTION Mutation is the change in the base sequence of DNA and it changes characteristics of an organism. The organism exhibiting changed characteristics is called mutant. The process of inducing mutation is called mutagenesis. Mutagenesis is a suitable method to develop new strain with superior qualities from a wild type organism. Usually X-ray, UV-ray and chemical mutagens are used for inducing variation. By this method, if wild type is unstable it would made into stable. P.chrysogenum strain was screened from wild type culture by culturing in a plates under biochemical test. It produces about 80-100 units of penicillin per ml.
- 5. Another example is the production of Wisconsin 5120. X-ray UV-ray P.chrysogenum X 1612 Wisconsin Q176 NTG Wisconsin 5120 (Commercial Strain) N-methyl-N-nitro-N-nitroguanidine (NTG) is a commercial strain used in industries for producing penicillin. It produces 2,500-5,000 units of penicillin per ml.
- 6. PROTOPLAST FUSION Protoplast are the cells devoid of cell wall. It is produced using lysosome (cell wall degrading enzyme) in isotonic solution. Fusion of protoplast obtained from somatic cells of fungi and bacteria is very useful to develop industrial strain in many cases. Hamlin and ball fused the protoplasts of two strains of cephalosporium acremonium using PEG (polyethylene glycol). The resultant protoplast produced more cephalosporin. Chang et.al fused the protoplast of two strains of penicillium chrysogenum. The resultant protoplast produced penicillin-v.
- 7. RECOMBINANT DNA TECHNIQUE Many industrial strains have been developed using rDNA technology . The gene is transferred into the harmless microbe through DNA vector is called cloning vehicle. So organism become improved strain for the production of particular product. Eg: the human insulin gene was transferred into the E.coli K12 strain using cloning vehicle pBR322 . Hence E.coli K12 started to producing insulin.
- 8. REFERENCE 1) Biotechnology; V.Kumeresan 2) Biotechnology; B.D.Singh