Chapter ad vant disadvantage ii) High biomass yield coefficient. iii) Filamentous growth iv) Tolerance to broad range of temperatures v) Tolerance to broad range of pH vi) High spontaneous mutation rate vii) Low aeration requirement. put i Disadvantage. High growth rate is needed for high output(weight of biomass roduced per unit of time). The only advantage could be that as the RNa content of cells is generally proportional to the growth rate, growth at low growth rate could result in a product with lower nucleic acid content. 1) Advantage. The biomass yield coefficient (weight of cells produced per unit of ubstrate consumed)should be high in order to give a high output. It also ensures efficient utilisation of the(expensive )substrate. Advantage/Disadvantage Compared to unicellularorganisms, filamentous ones are easier (and cheaper) to recover from fermentation media( by sieving or rotar vacuum filtration)and have a more fibrous texture. However dense broths filamentous organisms can be difficult to aerate and wall growth can cause problems such as clogging of pipes and valves o Advantage. Temperature increases can occur during fermentations, as growth processes are exothermic. The ability of an organism to tolerate raised temperature would reduce the need for cooling. The ability of an organism to grow at ambient temperatures also overcomes the need for heating and cooling The broader the temperature range tolerated, the less the need for temperature v) Advantage. The pHof a medium tends to change during fermentation. Most often media are buffered, and the fermentor is fitted with pH control. However, the bility to tolerate a wide range of ph can overcome the need for pHoontrol Fungi generally grow at lower pH than bacteria Use can sometimes be made of this by operating fungal processes at very low pH, preventing bacterial growth. This means that an aseptic process (using sterilising procedures to maintain a pure culture)will be less prone to contamination if aseptic procedures fail. In some circumstances non-aseptic (non-sterile) processes can be operated, saving Disadvantage Organisms for SCP production require a high degree of genetic stability. We have been considering the characteristics an organismmust have for sCP production. These characteristics are under genetic control and any mutation68 Chapter 4 advantage disadvantage i) Low growth rate. ii) High biomass yield coefficient. iii) Filamentous growth. iv) Tolerance to broad range of temperatures. v) Tolerance to broad range of pH. vi) High spontaneous mutation rate. vii) Low aeration requirement. Output i) Disadvantage. High growth rate is needed for high output (weight of biomass produced per unit of time). The only advantage could be that as the RNA content of cells is generally proportional to the growth rate, growth at low growth rate could result in a product with lower nucleic acid content. Advantage. The biomass yield coefficient (weight of cells produced per unit of substrate consumed) should be high in order to give a high output. It also ensures efficient utilisation of the (expensive) substrate. wall growth iii) AdvantageDisadvantage. Compared to unicellularorganisms, filamentous ones are easier (and cheaper) to recover from fermentation media (by sieving or rotary vacuum filtration) and have a more fibrous texture. However, dense broths of filamentous organisms can be difficult to aerate and wall growth can cause problems such as clogging of pipes and valves. Advantage. Temperature increases can occur during fermentations, as growth processes are exothermic. The ability of an organism to tolerate raised temperature would reduce the need for Cooling. The ability of an qanism to grow at ambient temperatures also overcomes the need for heating and cooling. The broader the temperature range tolerated, the less the need for temperature control. Advantage. The pH of a medium tends to change during fermentation. Most often media are buffered, and the fermentor is fitted with pH control. However, the ability to tolerate a wide range of pH can overcome the need for pH control. Fungi generally grow at lower pH than bacteria. Use can sometimes be made of this by operating fungal processes at very low pH, preventing bacterial growth. This means that an aseptic process (using sterilising procedures to maintain a pure culture) will be less prone to contamination if aseptic procedures fail. In some circumstances non-aseptic (non-sterile) processes can be operated, saving sterilisation costs. Disadvantage. Organisms for SCP production quire a high degree of genetic stability. We have been considering the characteristics an organism must have for s8 production. These characteristics are under genetic control and any mutation ii) iv) v) non-aseptic processes vi)