ROLE OF MICROORGANISMS IN THE FERMENTATION PROCESS

Initially, it might be hard to imagine how microorganisms contribute to the fermentation process. How can such small and microscopic cells unseen to the naked eyes produce such high volumes of products? How can such microorganisms produced such a rich diversity of fermentation products which are useful to human beings?

The answer to the first question is simple enough. One tiny microscopic microbial cell will not produce industrially significant volume of fermentation products. However, when we talk about billions and billions of microbial cells in the fermentation vat, the volume and concentration of fermentation products is industrially and economically significant!

The diversity of fermentation products produced by the microorganisms is attributed to the rich diversity of microorganisms which have a diverse metabolisms that can yield various types of fermentation products

WHY MICROORGANISMS ARE THE BEST CHOICE FOR FERMENTATION?

The success of using microorganisms for fermentation lies in their very microscopic and metabolic characteristics. It is good being small!

1 High surface area to volume ratio

Microorganisms are very very tiny creatures. Taking an example of a rod bacterium (imagine a brick!), we can see that it has six free surfaces that surrounds the bacterium. These six free surfaces interfaced with the surrounding environment from where they obtained their nutrients or to where they throw away their metabolic waste products.

With such a high number of free surface areas in a tiny volume of cell, it confers upon the bacterial cell a very high surface area to volume ratio. This very high surface area to volume ratio allows maximum or optimum surfaces for diffusions or molecular exchanges to occur between the microbial cell and the environment. No matter where the molecules are, they are easily accessible for diffusion into the microbial cell.

Compare this with the elephant which is such a huge animal. which has a very low ratio of surface area to volume ratio! If nutrients are to diffuse through the surface area of the elephant it would not be enough to supply every cell of the elephant!

Once the nutrient molecules diffuse through the cell wall and membrane, it can be easily transported to where its needed in the cell. The size of the cell is so microscopic that distance covered in the transportation of the molecules in the cell is a convenience!

With such an ease of diffusion of nutrient molecules from the environment into the cell, and the diffusion of waste products from within the cell outwards to the surrounding environment we can see that metabolism will be at optimum state.

The efficient nutrient uptake coupled with the small size of the cell will allow for rapid synthesis and reproduction of new cells. Microorganisms under ideal state will double up within hours. Animals like elephants and human may take months to reproduce themselves.

2 Mode of nutrients transportation

The nutrients which diffuse into the microbial can either use simple diffusion process which is powered by the differences in the concentration gradients between the environment and within the cell. For very small nutrient molecules, most would diffuse by the mechanism of passive diffusion. Larger and complex molecules use active or group transport which requires expansion or utilization of energy

Microbes easily reproduce asexually! There is no real need to have a opposite partner cells, get married and reproduce. They will just as easily split their cells into two daughter cells which will later grow into larger cells and repeat the cycle...



3 Genetic adaptability

Microorganisms generally show the ability to adapt to new environment. They can get easily adapted to living under different environmental conditions and also adapting to new sources of carbon or substrate. This ability is the result of various genetic adaptation which selects "successful" strains through mutation and genetic recombination. Some of the bacteria are even equipped with plasmids which can synthesize new enzymes that help the microorganisms exploit the new environment. The very short generation times and the high population generation will aid the selection and recombination process.

4 Metabolic diversity

The unique thing about microbes are their metabolic diversity shown by various members of the microorganisms. They have the ability to use different energy sources and to use different types terminal electron acceptors

Their ability to use different substrates is also correlated with the microbes ability to produce a diversity of fermentation products