Biotechnology is the industrial use of living organisms, or parts of living organisms, to produce food, drugs or other products.
Microorganisms are often used in industrial processes because they:
- are highly versatile, occupying a wide range of habitats, including extreme conditions
- have a rapid growth rate
- are small, and can be produced in large numbers in a small volume
- can be grown in the laboratory, so are not influenced by climate
- produce more enzymes per unit mass than larger organisms
- can be genetically manipulated to express genes for novel products or human biochemicals
- can be manipulated to produce secondary metabolites on demand.
Growth of a microorganism in closed culture
Bacteria multiply by binary fission, in which one cell divides into two daughter cells, doubling the number of cells every generation. The time taken for a bacterial population to double is called its generation time. Under optimal conditions, some bacteria can divide as frequently as once every 20-30 minutes. There are always factors preventing unlimited population growth:
- depletion of nutrients
- depletion of oxygen
- accumulation of toxic or acidic waste products
These limiting factors are density dependent: the greater the number of individuals in the population, the greater the effect of factor.
There are four recognisable phases of population growth:
- Lag phase: the bacteria adjust to new conditions, synthesising carriers to absorb nutrients of enzymes to digest them. This may involve switching on genes. Growth is slow.
- Exponential phase (logarithmic phase): the numbers of bacteria double in each unit of time. The geometric growth…