There are three types of fermentation processes and they are
- Batch fermentation
- Continuous fermentation
- Dual or multiple fermentation
- Batch fermentation
Batch fermentation is carried out in batches. Here, fermentation media is filled up to 80% space by fermentor, and the remaining space is used as head space. Head space plays an important role as some area of a fermentor is required for collection of air, gases, and foam which is produced during the fermentation process. Further, after inoculation of media the fermentor is steam sterilized and after sterilization, the nutrient media is cooled and inoculated with desired volume of inoculums under aseptic condition.
Fermentation process is carried out under optimum growth condition. It is stopped after specific period of time and the fermented media or broth are removed from the fermentor and the desired product is obtained.
The product obtained is passed through recovery and purification process. Later, the fermentor is cleaned and reused for the next batch. In this process, as the fermentation proceeds, the quantity of nutrients from the media gets depleted, and microbes and products increase. In batch fermentation, growth of micro-organism is slower down due to decrease of nutrients.
Advantages of batch fermentation
It requires less space, there are fewer chances of contamination and this process is easy to handle. The disadvantage is that it is a time consuming process and it requires more time for cleaning, sterilization, cooling. The yield of the product is also low.
- Continuous fermentation process.
In continous fermentation process fermentation runs continuously without emptying of fermentation tank. It involves continous addition of fresh media and withdrawal of fermentation product is constant.Each and every cell in fermentation media should be in log phase and not in stationary phase.The rate of addition of media should satisfy nutrient requirement of fermentation organism if rate of addition of media is slow there are chances that cells enter in stationary phase.There are three types of continuous fermentation processes.
i] Single stage continuous fermentation
ii] Single stage recycle continuous fermentation
iii] Multi-stage continuous fermentation