WHY UNDERSTANDING MICROBIAL PHYSIOLOGY IS IMPORTANT IN FERMENTATION TECHNOLOGY?

The fourth definition of the fermentation is the mass cultivation of microorganisms or single cells in a specially designed vessel called fermentor or bioreactor. It is in these vessels that optimum conditions are provided that can support the growth of high concentrations of microorganisms and/or to carry out the biological transformations.

In this definition which is probably proposed by engineers, there is no requirement for differentiation between aerobic or anaerobic conditions. It only refers to the technology of mass cultivation of single cells and biochemical transformations

In order to provide the optimal growth conditions to support the cultivation of microorganisms there is the need first of all to understand the requirements of growth of the microorganisms.
Then there is the need to understand the behaviour of the microorganisms grown at high concentrations in the fermentor.

It is rather foolish to admit the basic principle that one simply cannot control the process if one first of all do not understand the process involved. In simple statement : if we cannot or do not understand the physiology of the microorganisms in the fermentor environment, there is no point in the first place to build the fermentor or even try to control the process during the growth of the microorganisms in the fermentor. In most cases even if we proceed to carry out the fermentation process we will not be able to control the growth of the microorganisms or the fermentation process optimally.

It is a sad thing to say that the knowledge of microbial physiology in standard microbiology textbooks are too limited or have no connection with the situation in the fermentation technology. An average microbiology textbook is too general to be applied to the field of fermentation technology. Traditional microbiology textbooks are often too taxonomic, too medically inclined or too ecological in content. Try reading the popular textbook on microbiology by Brock and Madigan! There are simply too few pages being allocated to industrial and environmental microbiology.

If this is bad for the microbiology students, its even worst for the engineering students whose knowledge on microbiology is even weaker.

To compound the disaster in teaching microbiology for fermentation technology, the subjects are more often than not taught by biologists or microbiologists who are not inclined or knows nothing about fermentation technology. This will lead to poor input of the relevant part of microbiology needed by fermentation technology students. A lot that will be taught will show no connection or irrelevant to the subject of fermentation technology. I might even say it will be far worst when chemical engineers have to teach the subject of microbiology to their engineering students.

What I have observed in engineers writing books on microbiology for engineering students are either the subjects of microbial physiology become too mathematical or they would teach what a general microbiology is about. It is doubtful they can give in depth understanding to the subject.
( no wonder students sleep in their lectures)

The internal environment for the cultivation of high concentration of microorganisms is far different from those in nature. In industrial fermentation there is the clear intention of cultivating high concentration of microorganisms within a very limited and confined volume. This situation is often not seen in other fields of microbiology. As such the behaviour and growth of microorganisms in reacting to the environment of the fermentor or bioreactor is very different than normally encountered.

The study of microbial physiology of microorganisms in the fermentor is therefore different and more challenging. At the same time understanding of the microbial physiology of microorganisms is essential in trying to obtain optimal growth conditions for the microorganisms and maximum yield of fermentation products and biotransformations.

If engineers or biotechnologists do not understand the physiology of the microorganisms in the bioreactor it will be very difficult for them to design fermentors which optimize microbial growth and fermentation products. The complexity of the microbial physiology of microorganisms in fermentor is further intensified by the two way interactions between the microorganisms and the fermentor. This means that while the environment of the fermentors can affect the microorganisms, the activity of the microorganisms too can affect the function of the fermentor

One example of the challenges facing microbial physiology of microorganisms in the fermentor is the tendency for the microorganisms to form microbial aggregates such as flocs, granules and pellets while growing in the fermentor. These microorganisms in the form of microbial aggregates will affect the physiology of the microorganisms especially with reference mass transfer of nutrients, waste products diffusions and gas exchanges. These aggregates too will affect the general viscosity of the fermentation broth