Microorganisms in Biotechnology

Microorganisms, or microbes, are tiny organisms that are usually too small to see without a microscope. They include bacteria, yeasts, microscopic fungi, and other microscopic organisms.

Microorganisms are extremely important in biotechnology because they can perform useful chemical reactions, reproduce rapidly, and often be grown in large quantities. Humans use microbes to produce foods, medicines, enzymes, fuels, and many other useful substances.

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What Are Microorganisms?

Microorganisms are organisms that can only be seen clearly using magnification.

Important groups used in biotechnology include:

• bacteria
• yeasts
• other microscopic fungi
• some microscopic algae

Two of the most important groups in industrial biotechnology are bacteria and yeast.

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Bacteria in Biotechnology

Bacteria are single-celled microorganisms.

Although some bacteria can cause disease, many bacteria are harmless or beneficial. Certain species are extremely useful in biotechnology.

Bacteria are used to produce:

• yogurt and other fermented foods
• medicines
• enzymes
• vitamins
• chemicals
• biofuels
• genetically engineered proteins

One important advantage of bacteria is that they can reproduce very quickly under suitable conditions.

This allows scientists and industries to produce large populations of bacterial cells in relatively short periods of time.

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Bacteria and Yogurt

Certain bacteria are used to convert milk into yogurt.

Examples include bacteria from the genera Lactobacillus and Streptococcus.

These bacteria use the sugar lactose found in milk and produce lactic acid.

As lactic acid accumulates:

• the pH decreases
• milk proteins change
• the milk becomes thicker
• the characteristic sour flavour develops

This is an example of fermentation.

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Yeast in Biotechnology

Yeasts are single-celled fungi.

One of the most widely used species is Saccharomyces cerevisiae, commonly called baker's or brewer's yeast.

Humans have used this microorganism for thousands of years.

Yeast can break down sugars and produce:

carbon dioxide + ethanol

This process is called alcoholic fermentation.

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Yeast and Bread Making

Yeast is added to bread dough along with ingredients containing carbohydrates.

The yeast obtains sugars and carries out fermentation.

One important product is carbon dioxide gas.

The carbon dioxide becomes trapped inside the dough, producing bubbles that cause the dough to rise.

During baking:

• the dough expands
• the bread develops its characteristic texture
• most of the ethanol produced during fermentation evaporates

Humans were using yeast to make bread long before they understood that microorganisms were responsible.

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What Is Fermentation?

Fermentation is a metabolic process in which microorganisms break down substances such as sugars and produce other substances.

Different microorganisms can produce different products.

For example:

Fermentation is therefore much more than food production. It can be used as a controlled industrial process for manufacturing useful substances.

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Industrial Fermentation

In biotechnology, microorganisms can be grown inside large containers called fermenters or bioreactors.

A bioreactor provides controlled conditions in which microorganisms can grow and produce a desired substance.

Scientists may carefully control:

• temperature
• pH
• nutrients
• oxygen concentration
• mixing
• microorganism concentration

These conditions can be adjusted to maximise growth or production.

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Why Are Conditions Controlled?

Microorganisms are living organisms, so their activity depends strongly on environmental conditions.

Temperature

Enzymes inside microbial cells work best within particular temperature ranges.

If the temperature is too low, reactions may occur slowly.

If the temperature becomes too high, enzymes can denature and cells may die.

pH

Microorganisms also have preferred pH ranges.

Industrial fermenters therefore monitor and adjust the pH.

Nutrients

Microorganisms need nutrients for:

• energy
• growth
• reproduction
• production of useful substances

Oxygen

Some processes require oxygen, while others work best with little or no oxygen.

The oxygen supply therefore depends on the microorganism and the product being produced.

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Microorganisms as Biological Factories

One of the most important ideas in modern biotechnology is that microorganisms can act like tiny biological factories.

Each cell contains enzymes and biological machinery capable of producing complex substances.

Scientists can sometimes genetically modify microorganisms so that they produce substances they would not normally make.

A famous example is human insulin.

Scientists can insert the human gene containing instructions for insulin production into bacteria or yeast.

The microorganisms can then produce insulin protein.

The general process is:

Human insulin gene

↓

Gene inserted into microorganism

↓

Microorganisms grown in large quantities

↓

Microorganisms produce insulin

↓

Insulin collected and purified

This approach is also used to manufacture other medically and industrially important proteins.

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Why Are Microorganisms Useful for Large-Scale Production?

Microorganisms have several characteristics that make them excellent biotechnology tools.

They Reproduce Quickly

Many microorganisms can reproduce much faster than plants or animals.

Large populations can therefore be produced relatively quickly.

They Require Little Space

Billions of microorganisms can be grown inside a single industrial bioreactor.

Growing large animals or plants would require much more land and resources.

Their Conditions Can Be Controlled

Temperature, nutrients, oxygen, and pH can be carefully controlled.

This makes production more predictable and efficient.

They Can Use Inexpensive Materials

Some microorganisms can grow using relatively inexpensive nutrient sources or biological waste products.

They Can Produce Complex Molecules

Microbial cells naturally contain the biological machinery needed to manufacture substances such as:

• proteins
• enzymes
• vitamins
• organic acids

They Can Be Genetically Modified

Some microorganisms can be engineered to produce specific useful products.

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Microorganisms in Medicine

Microorganisms are important in the production of many medical products.

They can be used to manufacture:

• insulin
• certain vaccines and vaccine components
• enzymes
• hormones
• antibiotics
• other therapeutic proteins

The ability to grow microbes under carefully controlled conditions allows large quantities of these products to be manufactured consistently.

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Microorganisms and Enzymes

Industries also use microorganisms to manufacture enzymes.

Microbial enzymes are used in:

• food processing
• detergents
• textile production
• paper manufacturing
• biofuel production

For example, some microorganisms produce proteases, which break down proteins.

Proteases can be added to biological laundry detergents to help remove protein-containing stains.

Other microorganisms produce enzymes that break down starches or fats.

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Microorganisms and Biofuels

Microorganisms can also help produce biofuels.

For example, yeast can ferment sugars to produce ethanol.

The ethanol can be separated and used as a fuel or mixed with gasoline.

Other microorganisms are being investigated for the production of:

• methane
• hydrogen
• biodiesel-related products
• other renewable fuels

This makes microbial biotechnology potentially useful in reducing dependence on some fossil resources.

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Evaluating the Benefits of Microorganisms

Using microorganisms provides many advantages.

However, biotechnology processes must still be carefully managed.

Potential challenges include:

• contamination by unwanted microorganisms
• maintaining suitable growth conditions
• separating and purifying the desired product
• preventing genetically modified organisms from accidentally escaping
• ensuring products are safe and consistent

An evaluation should therefore consider both the benefits and limitations of using microorganisms.

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Traditional and Modern Uses

Microorganisms connect traditional and modern biotechnology.

Traditional Biotechnology

Microbes are used for:

• bread
• yogurt
• cheese
• fermented vegetables
• other fermented foods

Modern Biotechnology

Microbes are used for:

• recombinant proteins
• medicines
• industrial enzymes
• biofuels
• engineered chemicals
• research

The microorganisms may be similar, but modern biotechnology gives scientists much greater ability to control and modify the biological processes involved.

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Did You Know?

Microorganisms can produce useful substances on an enormous scale.

Industrial bioreactors can hold thousands or even hundreds of thousands of litres of liquid culture. Inside these vessels, vast populations of microorganisms can be maintained under carefully controlled conditions.

This allows microscopic cells to become powerful tools for large-scale manufacturing.

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Key Terms

Microorganism – An organism that is usually too small to be seen clearly without magnification.

Bacteria – Single-celled microorganisms, many of which have important biotechnology applications.

Yeast – A group of single-celled fungi used extensively in fermentation.

Fermentation – A metabolic process used by microorganisms to convert substances such as sugars into other products.

Bioreactor – A controlled vessel used to grow cells or microorganisms for biotechnology production.

Industrial biotechnology – The use of biological organisms and processes to manufacture useful products on a large scale.

Genetic modification – Deliberately changing an organism's genetic material.

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Key Takeaways

• Bacteria and yeast are among the most important microorganisms used in biotechnology.
• Yeast is used in fermentation to produce carbon dioxide and ethanol.
• Lactic acid bacteria are used to produce yogurt and other fermented foods.
• Microorganisms can be grown in large bioreactors under carefully controlled conditions.
• Temperature, pH, nutrients, and oxygen can be controlled to maximise production.
• Microorganisms reproduce rapidly and require relatively little space.
• Microbes can act as biological factories, producing useful chemicals, enzymes, fuels, and medicines.
• Some microorganisms can be genetically modified to manufacture specific products such as human proteins.
• Microorganisms are useful for large-scale production because they are fast-growing, controllable, versatile, and efficient.
• Evaluating microbial biotechnology requires considering both its significant benefits and challenges such as contamination, containment, and product purification.