Abira Khan

 The first stage in the screening for microorganisms of potential industrial application  Involves obtaining either pure or mixed cultures followed by their assessment

 The nutritional characteristics of the organism  The optimum temperature of the organism  The reaction of the organism with the equipment to be employed and the suitability of the organism to the type of process to be used  The stability of the organism and its amenability to genetic manipulation  The productivity of the organism, measured in its ability to convert substrate into product and to give a high yield of product per unit time  The ease of product recovery from the culture

 The ideal isolation procedure commences with environmental source (frequently soil) the  Industrially important characteristic is used as a selective factor  Selective pressure may be used in isolation of organisms

 Isolation methods utilizing selection of the desired characteristic 1. Enrichment liquid culture 2. Enrichment culture using solid media  Isolation methods not utilizing selection of the desired characteristic

 Antibiotics were initially detected by growing potential producer on an agar plate in the presence of an organism (or organisms) against  The microbial isolate could be grown in liquid culture and the cell-free broth tested for activity  Inhibition of enzymes  Receptor-ligand binding assays

 The provision of test organisms that have increased sensitivities, or resistances, to known agents. For example, the use of super-sensitive strains for the detection of β -lactam antibiotics  (The cloning of genes coding for enzymes or receptors that may be used in inhibitor or binding screens makes such materials more accessible and available in much larger amounts  The development of reporter gene assays.  Molecular probes for particular gene sequences  The development of immunologically based assays such as ELISA

 Storage at reduced temperature 1. Storage on agar slopes 2. Storage under liquid nitrogen  Storage in a dehydrated form 1. Dried cultures 2. Lyophilization  Quality control of preserved stock cultures

 Selection of induced mutants synthesizing improved levels of primary metabolites 1. Modification of the permeability 2. Isolation of mutants which do not produce feedback inhibitors or repressors 3. The use of auxotrophs for the production of primary metabolites 4. Isolation of mutants that do not recognize inhibitors or repressors- Analogue resistant, Revertant

 Isolation of induced mutants producing improved yields of secondary metabolites where directed selection is difficult to apply 1. Isolation of auxotrophic mutants 2. Isolation of resistant mutants- Analogue/Feedback effect/Toxic effect/Toxic effects (Secondary) 3. Isolation of revertant mutants  Recombination systems 1. Application of the parasexual cycle 2. Protoplast fusion techniques 3. Recombinant DNA techniques- Heterologous proteins, improvement of native microbial products

 Improvement of industrial strains by modifying properties other than the yield of product 1. Stable strains 2. Strains resistant to infection 3. Non-foaming strains 4. Strains which are resistant to components of the medium 5. Morphologically favorable strains 6. Strains which are tolerant of low oxygen tension 7. Elimination of undesirable products from a production strain 8. Strains producing new fermentation products

 Concerted or multivalent feedback control  Co-operative feedback control  Cumulative feedback control  Sequential feedback control  Isoenzyme control

 Principles of Fermentation Technology- Stanbury- 2nd edition, Chapter 3