FERMENTATION

Fermenter Fermenter 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.

INDUSTRIAL FERMENTERS

DESIGN OF FERMENTER Components of fermenter: Basic component includes drive motor, heaters, pump, etc. Vessels and accessories Peripheral equipment (reagent bottles) Instrumentation and sensors

Various components of an ideal fermenter for batch process are:

Fermenter construction 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

Optimisation of the Fermenter System contaminating 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 exists

Basic fermenter configuration 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.

Microbial Growth Kinetics Microbial 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 Phase Stationary Phase Death Phase

Microbial Growth Kinetics 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 Kinetics Exponential 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 Kinetics The 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 Kinetics Stationary 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 Kinetics Death 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 sustainability

Metabolites Primary metabolites are produced during active cell growth (log phase)/ trophophase Secondary metabolites are produced near the onset of stationary phase/ idiophase products which do not have an obvious role in cell metabolism

Metabolites

Metabolites

PRODUCTION OF PENICILLIN Penicillin was the first important commercial product produced by an aerobic, submerged fermentation First antibiotic to have been manufacture in bulk. Used as input material for some semi synthetic antibiotics. It is fermented in a batch culture.

Commercial Production Of Penicillin Like all antibiotics, penicillin is a secondary metabolite, so is only produced in the stationary phase.

The yield of penicillin can be increased by: Improvement in composition of the medium Isolation 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 main stages of Penicillin production are: