Bioreactor vs Fermentor
The process of fermentation is known to mankind for thousands of years but its scientific studies were first conducted by French scientist Louis Pasteur in 1850’s when he studied formation of lactic acid. He found that souring of milk was a result of activity of living organisms, and not a chemical change as was thought earlier. Recent advances in techniques in the field of fermentation have led to the development of fermentors and bioreactors that are both based upon the activities of living organisms. Despite similarities in working principle, there are differences in a fermentor and a bioreactor that will be discussed in this article.
While in earlier times, the process of fermentation was mainly used for production of brewing alcoholic beverages only, with the increase in our knowledge about bacteria and fungi, fermentors have been developed that are being put to more productive uses. Bioreactors are a step ahead in design and construction. While fermentors are systems used for growth and maintenance in a controlled manner, of a population of bacterial or fungal cells, bioreactor is a system used for growth and maintenance of mammalian and insect cells. Thus it is clear that there are natural differences between the two, and these differences are enlisted below.
• While mammalian cells are fragile having shear sensitive cell membranes, bacterial cells are robust as they have strong cell walls.
• Mammalian cells are slow in their growth (they have 24 hour doubling time). On the other hand, bacterial cells are fast growing and double in just 20 minutes.
• Insect and mammalian cells have low oxygen demand whereas bacterial cells have a very high oxygen demand
• There is no viral threat in case of bacterial cells whereas this threat is present in case of mammalian cells and has to be either inactivated or removed.
There are differences in sterilization process also. While in the case of a fermentor, it has to be sterilized full, a bioreactor is so designed so as to be sterilized empty.
Bioreactors are large in comparison to fermentors and range in size from a few liters to cubic meters whereas fermentors are typically small having a capacity of up to 2 liters. Bioreactors are cylindrical vessels made of stainless steel.