Industrial Fermentation refers to the processes involved for large scale culture of microorganisms under controlled parameters of Nutrient composition, Temperature, pH, Oxygen level and other such factors which enable the production microorganism to mass produce the product of interest. It is an important process which has to be thoroughly executed to achieve desired level of target products and needs to be optimized at every stage prior to the main large scale fermentation. But the transition from Discovery of Microorganisms, to their optimization and the actual fermentation process has various stages in between.
Microorganisms have a tendency to adapt slowly to changes around them, hence there are procedures which need to be followed which in technical terms is known as "Upscaling" or "Upstream Processing". Since the cell population post optimization processes, such as Induced Mutations or Genetic Engineering, is very low and not sufficient for large scale fermentation, they need to be multiplied to a large population of microorganisms gradually.
The preserved production microorganism is first transferred to agar slants to start the process. A nutrient medium is added to the agar slants and agitated so a microbial suspension is prepared. This is now transferred to a bottle which contains sterile medium. The bottle is incubated at suitable temperatures to allow the microorganism to start multiplying.
Post a suitable amount of time and growth, the cell suspension from the bottle is transferred to shake flasks containing a liquid nutrient medium. The medium is sterilized in autoclaves prior to addition of the production microorganism. These flasks are now placed in an incubator shaker, where they are incubated at a controlled temperature along with constant agitation. The agitation allows for aeration and the cells now start multiplying at a rapid pace. This serves as a Working Culture which is used to prepare the Innoculum for the large scale fermentation.
There is yet another step between the actual large scale fermentation process and the working culture stage, the one of Seed Fermentation. This refers to the small scale fermentation carried out in Laboratory Fermenters (or Seed Fermentors). This is a small scale version of a large fermenter, having complete functionalities to control the parameters of pH, Temperature, Aeration and Monitor of Dissolved Oxygen, Foam control etc. The microbial cell suspension from the Shake flasks are used as Inoculum for the Seed Fermentation. The medium contains all the essential nutrients in a calculated composition to allow for effective growth of the microorganism and produce the metabolite of interest. This simulates the large scale fermentation process and allows monitoring of the process before scaling it for bulk production.
The Seed fermentation process is carried out for 1-2 days or more depending upon the production microorganism and this is now used as the microbial inoculum for the bulk fermentation process. The large scale process may be done in Submerged Fermentation or Solid Substrate Fermentation.
Submerged Fermentation refers to the mass culture of microbial cells in a liquid nutrient medium under controlled parameters of pH, Temperature, Dissolved Oxygen, Aeration, Foam control etc. These are carried out in large steel vessels specifically designed for the process along with instrumentation necessary to monitor the parameters and supplementation of additives to control them.
Solid Substrate Fermentation is the culture of microbial cells in a solid medium which serves as the nutrient and the anchor for cell growth. The metabolite production occurs near the surface of the solid medium which translates for fewer processing steps while downstream processing or recovery of the products. Also recent works in the field of Solid Substrate Fermentation have shown relatively higher yields as compared to Submerged Fermentation.
Since Fermentation is an important part of the manufacturing process, we are constantly looking at new approaches to optimization. Solid Substrate Fermentation holds the potential for future innovation and increased productivity in enzyme manufacturing, and we are actively involved in pursuing this production technology.