- Slides: 18
Fermentation • Submerged fermentation (Smf)/ Liquid fermentation (Lf) • Solid state fermentation (SSF)
Submerged fermentation • Media concentration is very much lower as compared to water content. • Required processed ingredients are expensive • Higher water activity becomes the major cause of contamination in SLF • Large-scale bioreactors are required because media is very much diluted.
• High air pressure consumes more power and there is poor transfer of gas in SLF • Vigorous mixing makes diffusion easy. • Online sensors are available and sampling is easy for biomass measurement. • Water makes downstream process difficult and very expensive. • High quantity of liquid waste is produced, causes difficulties in dumping
Solid state fermentation (SSF) • Organisms requiring less water for growth are preferred such as filamentous fungi. • Inert support (natural or artificial), containing all components for growth in the form of solution • Less chances of contamination because of low availability of water • Small size bioreactors can be used.
• Less consumption of energy for aeration and gas transfer. • Limiting factor for growth is diffusion of nutrients • Lots of difficulties in measuring the quantity of biomass present and other online processes • Downstream processing is easy, cheaper and less time consuming. • Liquid waste is not produced
Fermentation Process • Batch • Fed batch • Continuous
Batch Fermentation • Fermentation Kinetics • μ (h-1): Specific growth rate dx/dt • Yx/s: g of cell biomass formed/g of substrate consumed • Yp/x: Product produced/g of cells formed • Yp/s: Product produced/g of substrate consumed
Continuous Fermentation • Homogeneously mixed Bioreactor • Chemostat or turbidostat • Chemostat- growth controlled by adjusting conc. Of substrate • Turbidostat- cell growth kept constant, by using turbidity to monitor biomass conc. • Plug flow Reactor- solution flows through tubular reactor
Fermentation classification • Type 1 - product directly derived from primary metabolism. E. g. SCP, Ethanol • Type II- product also derived from substrate, but production takes place in secondary pathway e. g. citric acid • Type III- primary metabolism function first, accompanied by substrate consumption, growth, product is formed by intermediary metabolism e. g. Antibiotics
Flask Fermentation • Lab Scale
Fermenter • Height and width 2: 1 -6: 1 • 4 -12 baffles 1: 10 -1: 12 • 4 -8 radial blades • SS jacket 316, 317
Sterilization • In situ • Ex situ
Air Lift fermenter