Microorganisms are able to continuously carry out a series of sequential reactions to maintain life and will balance forward and back reaction, control levels of biochemicals produced, react to signals directing the organism to carry out different functions depending upon external stimuli and generate (and store) intermediates and energy for the complex functions of life. This truly amazing feat is replicated in differing ways across many life forms from microorganisms to those seen as higher up the evolutionary ladder. The numbers of enzymes and chemicals involved are large and their interrelationship is complex.
We now have the ability to "tune" biochemical pathways to alter the ways in which microorganisms carry out these elaborate and complex processes in order to get them to produce materials in different quantities, molecules with altered structure and to redirect the conversion of a starting material into one main product.
Altering the biochemical pathways of a bacterium or fungus, Metabolic Pathway Engineering, has proved valuable to many market sectors in industry and has led to the discovery of novel molecules valuable to society.
Biofuels and Plant By-Products
Modification of the presence and balance of enzymes can give an organism that will convert sugar in a particular way to give predominantly a biofuels or a precursor to a polymer, for example. Increasing the amount of sugar converted into bioethanol - rather than lactic acid or formic acid - gives a more efficient conversion to biofuels. Alternative modification to produce predominantly lactic acid give the precursor to polylactate polymer.
The ability of an organism to convert C5-sugars as well as C6-sugars into product also means that more plant by-products can be used for industrial products.
Genetic modification of organisms that naturally produce antibiotics can give processes to synthesise complex variants of large naturally occurring molecules that have altered, beneficial pharmaceutical properties. Polyketides and lantibiotic are examples of active agents that would be difficult to prepare by other means.
Metabolic Pathway Engineering has been used to persuade microorganisms to make large amounts of materials such as 1,3-propanediol (for textiles) and isoprene (for tyre manufacture) to provide consumer products that are cost effective, renewable and environmentally advantageous.
The opportunities for making a wide range of necessary starting materials for our manufacturing industries by harnessing biochemical pathways are great and increasingly so as novel biochemical pathways are discovered in marine organisms and other lesser studied life forms.