Post on 13-Jan-2016
Introduction to Fermentation
FERMENTATIONFermenter is a vessel or tank in which whole cells or cell-free enzymes transform raw materials into biochemical products and/or less undesirable by-products. It is also termed as Bioreactor.The basic function of a fermenter is to provide a suitable environment in which an organism can efficiently produce a target product that may be - cell biomass, - a metabolite, - or bioconversion product.
Fermenter
INDUSTRIAL FERMENTERS Components of fermenter:Basic component includes drive motor, heaters, pump, etc.Vessels and accessoriesPeripheral equipment (reagent bottles)Instrumentation and sensorsDESIGN OF FERMENTER
Various components of an ideal fermenter for batch process are:
corrosion resistant
non-toxic
withstand repeated sterilization with high pressure steam
mechanical stress
Visual inspection of the medium and culture is advantageous, transparent materials should be used Fermenter constructioncontaminating organisms
Culture volume should remain constant
Dissolved oxygen level must be maintained above critical levels of aeration and culture agitation for aerobic organisms
Parameters such as temperature of pH must be controlled, and the culture volume must be well mixed. Therefore a need for control existsOptimisation of the Fermenter System
A microbial fermentation can be viewed as a three-phase system, involving liquid-solid, gas-solid, and gas-liquid reactions.
The liquid phase contains dissolved nutrients, dissolved substrates and dissolved metabolites.The solid phase consists of individual cells, pellets, insoluble substrates, or precipitated metabolic products.The gaseous phase provides a reservoir for oxygen supply and for CO2 removal.
Basic fermenter configurationMicrobial Growth KineticsMicrobial Growth Kinetics describe how the microbe grows in the fermenter. This information is important to determine optimal batch times. The growth of microbes in a fermenter can be broken down into four stages:Lag Phase Exponential PhaseStationary PhaseDeath Phase
Lag Phase
This is the first phase in the fermentation process and it may be absent in certain fermentation processes.
It is a period of adaptation of the cells to their new environment.
Cell growth is minimal in this phase. Microbial Growth KineticsExponential Phase
This is the second phase in the fermentation process. It is also known as log phase.
The cells have adjusted to their environment and rapid growth takes place.
Cell growth rate is highest in this phase.
At some point the cell growth rate will level off and become constant.
Microbial Growth KineticsThe most likely cause of this leveling off is substrate limited inhibition.Substrate limited inhibition means that the microbes do not have enough nutrients in the medium to continue multiplying. Microbial Growth KineticsStationary phase
This is the third phase in the fermentation process.
The cell growth rate has leveled off and become constant.
The number of cells multiplying equals the number of cells dying.Microbial Growth KineticsDeath phase
The fourth phase in the fermentation process
The number of cells dying is greater than the number of cells multiplying
The cause of the death phase is usually that the cells have consumed most of the nutrients in the medium and there is not enough left for sustainabilityMicrobial Growth KineticsPrimary metabolites are produced during active cell growth (log phase)/ trophophase
Secondary metabolites are produced near the onset of stationary phase/ idiophaseproducts which do not have an obvious role in cell metabolismMetabolitesMetabolites
Metabolites
Penicillin was the first important commercial product produced by an aerobic, submerged fermentationFirst antibiotic to have been manufacture in bulk.Used as input material for some semi synthetic antibiotics.It is fermented in a batch culture.
PRODUCTION OF PENICILLINLike all antibiotics, penicillin is a secondary metabolite, so is only produced in the stationary phase.
Commercial Production Of Penicillin
Improvement in composition of the mediumIsolation of better penicillin producing mold sp. Penicillium chrysogenum which grow better in huge deep fermentation tank.Development of submerged culture technique for cultivation of mold in large volume of liquid medium through which sterile air is forced.The yield of penicillin can be increased by:
The main stages of Penicillin production are: