Both prokaryotic and eukaryotic organisms including plants, animals and microorganisms are used for biotechnological manipulations. Whole animals and plants are manipulated through genetic engineering to produce transgenic animals and plants respectively. In addition, bacteria and other eukaryotic cells have been genetically manipulated to produce non-microbial products such as human growth hormones, insulin, interferon, mammalian proteins and genes typical of which is insulin (hormone that regulates the blood sugar level) that can now be produced in large amounts through a genetically modified bacterium (Escherichia coli) or fungi (yeast). For the production of insulin in commercial quantities, the gene for human insulin is inserted into yeast or bacteria, from which large quantities of the human insulin are manufactured biotechnologically.
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Microorganisms used for biotechnological processes are in any of the following categories:
- Archaea: Archaea is a member of the phylogenetic tree of life aside prokaryotes and eukaryotes. They consist of a domain and kingdom of single celled microorganisms that are mainly prokaryotes. Formerly classified as bacteria, the members of the Archaea are very distinct from bacteria and eukaryotic cells. They are ubiquitously found in the environment including hot springs and salt lakes. Typical examples include methanogens which are Archaea that produce methane as a result of their metabolism.
- Bacteria: Bacteria are a domain of microbial life that consist mainly of prokaryotic cells that lack membrane bound organelles such as mitochondria. They are ubiquitously found in the environment. Typical example is Escherichia coli which have been exploited for the benefit of man and his environment through the principles of biotechnology. Many bacteria including lactic acid bacteria such as lactobacillus have been used since time immemorial to produce fermented food products such as cheese, yoghurt and wine.
- Fungi: Fungi are members of a group of microbes generally known as eukaryotes because they contain membrane bound organelles. They include yeast such as Saccharomyces cerevisiae used for the production of bread and mould such as Rhizopus species. Fungi are ubiquitously found in the environment. They possess several economic benefits to man and his environments.
- Algae: Algae are diverse group of organisms that are photosynthetic in nature. Organisms in this category are usually unicellular and multicellular in nature. They are ubiquitously found in the environment and they contain chlorophyll which is their primary photosynthetic pigment. For example, alginic acid (alginate) is extracted from brown algae; and it is used as gelling agents in food and in medical applications. Also, alginate is used in the field of biotechnology as a biocompatible medium for cell encapsulation and cell immobilization.
- Viruses: Viruses are small infectious agents that only replicates inside the cell of a living host. They infect all forms of life including other microbes. Viruses have several applications in medicine, industry and biotechnology; and they provide simple systems that can be used to manipulate and investigate the functions of other microbial cells.
Specific strains of any of these microorganisms can be used for biotechnological applications. Finding the right strain of microorganism to use for a biotechnological process is something of a herculean task as not all strains of a particular organism can be employed or genetically manipulated to produce a desired product. Through biotechnological tools such as polymerase chain reaction (PCR) and gene cloning techniques, the gene expression of a particular organism can be engineered and modified to start producing a product of commercial interest. But such organism must meet certain criteria for it to be qualified as a tool for biotechnological processes. Some of the qualities sought for when choosing microorganisms for biotechnological processes may include any of the following:
- Microorganisms with high growth rate that do not produce viscous culture broth are chosen.
- The organism must be able to produce desired products.
- The organism must be genetically stable.
- It must be genetically amenable and be easily manipulated.
- The organism must be able to degrade pollutants or convert them to environmentally-friendly compounds. This applies to environmental biotechnology.
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