Microorganisms in Industry and Biotechnology
4. Genetic Engineering and Microbes
Learning outcomes
- I can explain how microorganisms are used in genetic engineering.
- I can describe how microbes can produce useful proteins.
- I can identify examples of genetically engineered microorganisms.
- I can explain the production of medicines using biotechnology.
- I can evaluate benefits and concerns associated with genetic engineering.
What Is Genetic Engineering?
Genetic engineering is the deliberate modification of an organism's genetic material using biotechnology.
Scientists can:
- insert genes
- remove genes
- modify genes
- transfer genes between organisms
A gene contains DNA instructions that can be used to produce a particular:
RNA or protein product.
By transferring a useful gene into a microorganism, scientists can sometimes turn that microorganism into a biological factory for producing a desired substance.
Why Use Microorganisms?
Microorganisms such as bacteria and yeast are especially useful in genetic engineering because they:
- reproduce rapidly
- can be grown in large numbers
- require relatively little space
- can be cultured in bioreactors
- are comparatively easy to manipulate genetically
- can produce useful proteins
- can be grown under controlled conditions
Some microorganisms can therefore be engineered to manufacture substances originally produced by:
humans, animals, plants, or other organisms.
DNA Contains Instructions
DNA contains biological information.
A gene is a sequence of DNA that contributes to the production of a functional product, often a protein.
The basic flow of genetic information can be represented as:
DNA → RNA → protein
This relationship is fundamental to genetic engineering.
If scientists place an appropriate gene into a suitable microorganism, the microorganism may be able to use that genetic information to produce the:
desired protein.
Recombinant DNA
Recombinant DNA is DNA created by joining genetic material from different sources.
For example, scientists might combine:
a useful human gene + bacterial DNA
The resulting DNA can be introduced into bacterial cells.
If the system is designed correctly, the bacteria can express the inserted gene.
What Is a Plasmid?
Many bacteria contain small circular pieces of DNA called:
plasmids.
Plasmids are separate from the main bacterial chromosome.
They can replicate inside bacterial cells.
Scientists can modify plasmids and use them as:
vectors.
A vector is a DNA molecule used to carry genetic material into a cell.
Using a Plasmid as a Vector
A simplified genetic-engineering process is:
identify useful gene → prepare plasmid → insert gene into plasmid → introduce recombinant plasmid into bacteria → grow bacteria → bacteria express gene → collect useful product
This process forms the basis of many applications of:
recombinant DNA technology.
Step 1: Identify the Desired Gene
Scientists first determine which gene contains the instructions for the desired product.
For example, if scientists want microorganisms to help produce human insulin, they need genetic information corresponding to:
human insulin production.
The relevant DNA sequence can then be prepared for insertion into a vector.
Step 2: Prepare the Plasmid
A bacterial plasmid can be removed or constructed and then opened at a particular location.
Traditionally, enzymes called:
restriction enzymes
have been used to cut DNA at specific sequences.
These enzymes act like molecular:
scissors.
Restriction Enzymes
A restriction enzyme recognizes a particular DNA sequence and cuts the DNA at or near that sequence.
Different restriction enzymes recognize different:
DNA sequences.
Scientists can use appropriate enzymes to prepare both the desired DNA and plasmid for joining.
Step 3: Join the DNA
Another enzyme called:
DNA ligase
can join pieces of DNA together.
DNA ligase forms bonds in the DNA backbone.
A simplified model is:
plasmid DNA + desired gene → DNA ligase → recombinant plasmid
The recombinant plasmid now contains the new genetic information.
Step 4: Introduce the Plasmid into Bacteria
The recombinant plasmid must enter bacterial cells.
The uptake of external DNA by a bacterial cell is commonly called:
transformation.
Not every bacterial cell successfully takes up the plasmid.
Scientists therefore need methods to identify:
successfully transformed cells.
Step 5: Select the Modified Cells
Plasmids can contain marker genes that help scientists identify cells carrying the desired plasmid.
Cells containing the recombinant DNA can then be:
selected and grown.
Modern biotechnology uses several selection and screening techniques depending on the organism and application.
Step 6: Grow the Microorganisms
Once suitable genetically engineered microorganisms have been obtained, they can be grown in:
bioreactors.
The microorganisms are provided with controlled conditions including:
- nutrients
- appropriate temperature
- suitable pH
- oxygen when required
- mixing
Large microbial populations can then produce substantial amounts of the desired product.
Step 7: Produce the Protein
Inside the genetically engineered cell, the inserted gene can be:
expressed.
Gene expression involves:
DNA → RNA → protein
The microorganism therefore manufactures the protein encoded by the introduced genetic information.
This process can occur repeatedly as the microorganisms grow.
Step 8: Recover the Product
The useful protein must usually be separated from the microbial culture.
Depending on the process, this may involve:
- collecting the culture
- separating cells
- breaking cells open if necessary
- extracting the protein
- purifying the protein
- testing its quality
These stages are part of:
downstream processing.
Producing Human Insulin
One of the best-known applications of genetically engineered microorganisms is the production of:
human insulin.
Insulin is a hormone involved in regulating blood glucose concentration.
Biotechnology allows insulin to be manufactured using genetically engineered microorganisms rather than relying on extraction from animal tissues.
Simplified Insulin Production
A simplified model is:
human insulin genetic sequence identified
↓
DNA introduced into a suitable microbial production system
↓
engineered microorganisms grown
↓
insulin or insulin precursor produced
↓
product recovered
↓
product purified and processed
↓
quality tested
↓
medicine prepared
This is an important example of:
medical biotechnology.
Why Was Recombinant Insulin Important?
Historically, insulin for medical use was obtained from animals such as:
- pigs
- cattle
Recombinant biotechnology made it possible to manufacture human insulin using engineered microorganisms.
Advantages include:
- reliable large-scale production
- high product consistency
- production of human insulin
- reduced dependence on animal tissues
- highly controlled manufacturing
Bacteria and Yeast
Both bacteria and yeast can be useful in genetic engineering.
Bacteria
Advantages include:
- rapid reproduction
- relatively simple cultivation
- well-understood genetics
- plasmids are readily available as vectors
Yeast
Advantages include:
- rapid growth
- ability to perform some protein-processing steps that bacteria cannot
- extensive industrial use
- ability to grow in large fermenters
The best organism depends on the:
protein being produced.
Producing Human Growth Hormone
Genetically engineered microorganisms can also be used in the production of:
human growth hormone.
Growth hormone is a protein involved in growth and metabolism.
Recombinant DNA technology allows the relevant human genetic information to be expressed in microbial production systems.
The protein can then be purified for medical use.
Producing Vaccine Components
Genetically engineered microorganisms can produce proteins from:
pathogens.
These purified proteins can sometimes be used as components of vaccines.
For example, recombinant biotechnology is used in the production of certain:
hepatitis B vaccines.
How Can a Recombinant Vaccine Work?
A simplified process is:
pathogen gene identified → gene inserted into production cells → cells produce pathogen protein → protein purified → vaccine manufactured
The purified protein can act as an:
antigen.
The immune system can learn to recognize the antigen without requiring exposure to the complete disease-causing pathogen.
Producing Enzymes
Genetically engineered microorganisms can also manufacture:
enzymes.
Microbial enzymes are used in:
- food processing
- detergents
- medicine
- textiles
- paper production
- biofuel manufacturing
Genetic engineering can increase how much enzyme a microorganism produces or alter the characteristics of the enzyme.
Chymosin and Cheese
An important example is:
chymosin.
Chymosin is an enzyme used during cheese production to help coagulate milk.
Traditionally, chymosin was obtained from the stomachs of young calves.
Today, genetically engineered microorganisms can manufacture:
recombinant chymosin.
This is a major example of genetic engineering in everyday food production.
How Recombinant Chymosin Is Produced
A simplified process is:
gene for chymosin → inserted into suitable microorganism → microorganism cultured → chymosin produced → enzyme purified → used in cheese manufacturing
The genetically engineered microorganism acts as a:
production system.
The purified enzyme is the useful industrial product.
Genetic Engineering and Industrial Enzymes
Microorganisms can be modified to:
- produce more enzyme
- tolerate industrial conditions
- use different raw materials
- produce enzymes with desirable properties
This can improve industrial:
efficiency.
Genetically Engineered Microorganisms in Agriculture
Microorganisms can also be engineered for agricultural applications.
Potential uses include:
- producing animal-feed enzymes
- supporting nutrient processing
- producing agricultural chemicals biologically
- improving industrial processing of crops
Some applications remain areas of active research and development.
Microorganisms and Biofuels
Scientists can genetically modify microorganisms to improve production of:
biofuels.
For example, microbes may be engineered to:
- break down plant material more efficiently
- tolerate higher concentrations of ethanol
- produce greater quantities of fuel
- use a wider variety of sugars
The goal is to make biological fuel production more:
efficient.
Metabolic Engineering
Genetic engineering can modify an entire metabolic pathway rather than only adding one gene.
This is called:
metabolic engineering.
Scientists alter genes controlling cellular reactions so that more resources are directed toward producing a desired:
chemical.
Microbial Cell Factories
Genetically engineered microorganisms are sometimes described as:
microbial cell factories.
Imagine a bacterium receiving sugar as its raw material.
Through a series of enzyme-controlled reactions, the cell converts the sugar into a useful product.
Scientists can modify these pathways to increase:
product yield.
Genetic Engineering vs Selective Breeding
Selective breeding chooses organisms with desirable existing characteristics and breeds them.
Genetic engineering directly modifies:
DNA.
Genetic engineering can also transfer genetic information between organisms that would not normally reproduce with one another.
This makes genetic engineering fundamentally different from traditional selective breeding.
Genetic Engineering vs Fermentation
These terms describe different things.
Genetic engineering changes genetic information.
Fermentation or microbial cultivation grows microorganisms under controlled conditions.
They are often used together:
genetic engineering creates the production strain → industrial cultivation grows the strain → useful product is manufactured
Benefits of Genetically Engineered Microorganisms
Genetically engineered microorganisms can provide several advantages.
They may:
- manufacture human proteins
- produce medicines at large scale
- produce consistent products
- reproduce rapidly
- require relatively little space
- reduce dependence on animal sources
- manufacture industrial enzymes
- use renewable materials
- be optimized for particular processes
These advantages make microbial biotechnology economically important.
Benefit: Large-Scale Production
Once an appropriate microbial strain has been developed, enormous populations can be grown in:
bioreactors.
Each cell can produce the desired substance.
Billions or trillions of cells working simultaneously can create significant quantities of product.
Benefit: Product Consistency
Industrial production requires:
consistent quality.
A carefully maintained microbial strain can be grown under standardized conditions.
This helps manufacturers control:
- product identity
- purity
- concentration
- performance
Consistency is particularly important for:
medicines.
Benefit: Reduced Dependence on Animals
Some substances that were historically extracted from animal tissues can now be produced using:
recombinant biotechnology.
This can:
- increase supply
- improve consistency
- reduce reliance on animal tissues
- simplify some aspects of purification
Recombinant insulin is a major example.
Benefit: Producing Complex Biological Molecules
Some proteins are difficult to manufacture using ordinary chemical synthesis.
Living cells already contain molecular machinery for:
protein production.
Scientists can use this machinery to manufacture useful biological molecules.
Concern: Containment
Genetically engineered microorganisms used in industry must be:
carefully contained.
Facilities use physical and biological safeguards designed to prevent inappropriate release.
The required level of containment depends on the organism and its characteristics.
Concern: Environmental Effects
A question sometimes raised is:
What would happen if a genetically modified microorganism entered the environment?
Risk depends on factors such as:
- ability to survive outside the facility
- ability to reproduce
- genes it carries
- possibility of gene transfer
- interactions with other organisms
These risks are evaluated before particular applications are approved or used.
Horizontal Gene Transfer
Bacteria can sometimes exchange genetic information through:
horizontal gene transfer.
This raises an important consideration when designing genetically modified microorganisms.
Scientists must consider whether introduced genes could potentially move into other:
microbial populations.
Antibiotic Resistance Marker Genes
Historically, antibiotic resistance genes have often been useful as markers for identifying genetically modified bacteria.
However, their use can raise concerns about:
antimicrobial resistance.
Modern biotechnology can use alternative selection methods in applications where resistance markers are undesirable.
Concern: Safety of the Product
A genetically engineered microorganism may produce a useful substance, but that substance must still be:
tested.
For medicines, manufacturers need to verify properties such as:
- identity
- purity
- biological activity
- sterility
- consistency
- safety
Genetic engineering does not eliminate the need for rigorous:
quality control.
Concern: Unintended Changes
Changing DNA can sometimes produce:
unexpected biological effects.
For example, altering one metabolic pathway may influence another.
Scientists therefore test engineered organisms to determine whether they behave as:
expected.
Concern: Ethical Questions
Genetic engineering can raise ethical questions such as:
- Should particular organisms be genetically modified?
- Who controls genetically engineered technologies?
- Who benefits from the technology?
- How should risks be evaluated?
- How should genetically modified organisms be regulated?
- How should intellectual property be handled?
These questions involve both:
science and society.
Concern: Cost
Developing a genetically engineered production organism can require substantial investment.
Costs may include:
- research
- laboratory equipment
- bioreactors
- testing
- purification
- quality control
- regulatory approval
However, once developed, a successful process may allow efficient:
large-scale production.
Evaluating Genetic Engineering
An evaluation should consider both:
benefits and concerns.
Possible benefits
- production of important medicines
- reliable large-scale manufacturing
- production of useful enzymes
- reduced dependence on animal sources
- more efficient industrial processes
- new biological products
- potential environmental applications
Possible concerns
- environmental release
- gene transfer
- contamination
- unintended biological effects
- ethical concerns
- regulatory challenges
- economic costs
The evidence should be evaluated for the:
specific application rather than assuming every genetic engineering application has identical benefits or risks.
Risk and Benefit Depend on the Application
Consider two engineered microorganisms:
Microorganism A: contained inside a pharmaceutical factory and used to produce insulin.
Microorganism B: deliberately released into an ecosystem.
These applications create very different:
risk profiles.
Therefore, evaluating genetic engineering requires asking:
What organism? What gene? What product? What environment? What containment? What benefit? What risk?
Genetic Engineering and Everyday Life
Microbial genetic engineering may seem like advanced laboratory science, but its products can appear in everyday life.
Examples include:
- recombinant insulin
- some vaccine components
- cheese-making enzymes
- industrial enzymes
- biotechnology-produced food ingredients
The genetically engineered microorganism itself does not necessarily appear in the:
final product.
Often, the microorganism produces a substance that is later purified.
Example: Medicine
Suppose bacteria are genetically engineered to manufacture a human protein.
The process might be:
gene → recombinant microorganism → bioreactor → protein production → purification → testing → medicine
The patient receives the purified:
medicine,
not necessarily the production microorganism.
Example: Cheese
A genetically engineered microorganism produces:
chymosin.
The enzyme is collected and purified.
The chymosin is then used during:
cheese production.
This demonstrates how genetic engineering can indirectly become part of an everyday manufacturing process.
Example: Industrial Enzyme
Scientists engineer a bacterium to produce large quantities of an enzyme that breaks down starch.
The bacteria are grown in:
bioreactors.
The enzyme is recovered and purified.
A manufacturer can then use the enzyme to process:
starch-containing materials.
Worked Example 1
Scientists insert a human gene into a bacterial plasmid.
What has been created?
A form of:
recombinant DNA.
Worked Example 2
What is the purpose of a plasmid during bacterial genetic engineering?
It acts as a:
vector
that carries genetic information into bacterial cells.
Worked Example 3
An enzyme cuts a plasmid at a particular DNA sequence.
What type of enzyme could this be?
A:
restriction enzyme.
Worked Example 4
Which enzyme can join pieces of DNA?
DNA ligase.
It forms bonds in the DNA backbone.
Worked Example 5
A bacterium takes up a recombinant plasmid.
What is this process commonly called?
Transformation.
The bacterium has acquired external genetic material.
Worked Example 6
Engineered microorganisms contain a human gene but produce very little protein.
Scientists want to increase production.
What might they investigate?
They could examine:
- gene expression
- growth conditions
- nutrient supply
- temperature
- pH
- oxygen
- regulatory DNA sequences
Both genetic design and culture conditions affect:
protein yield.
Worked Example 7
Why must a recombinant medicine be purified?
The microbial culture contains many substances besides the desired:
protein.
Purification removes cells, unwanted proteins, and other contaminants so the final medicine meets appropriate standards.
Worked Example 8
A student says genetically engineered bacteria contain only the inserted gene.
Is this correct?
No.
The bacteria still contain their normal genome.
The introduced gene represents only a small addition or modification to their genetic information.
Worked Example 9
Why can genetically engineered microbes produce proteins from another species?
The basic genetic code and mechanisms of gene expression are widely shared among living organisms.
If the gene is placed in an appropriate expression system, the microbial cell can use the genetic instructions to produce the encoded:
protein.
Some proteins require additional processing, so the production organism must be chosen carefully.
Worked Example 10
A company wants to release an engineered bacterium into agricultural soil.
Why would this require a different risk assessment from bacteria kept inside a sealed factory?
Released bacteria could interact with:
- natural microbial communities
- plants
- animals
- ecosystems
Scientists must therefore consider survival, reproduction, gene transfer, and environmental effects.
Comparing Traditional and Recombinant Production
Traditional extraction
Useful substance obtained from:
an organism or biological tissue
Possible limitations:
- limited supply
- variable source material
- difficult extraction
Recombinant microbial production
Useful gene placed into:
production microorganisms
Possible advantages:
- rapid microbial growth
- controlled production
- scalable manufacturing
- consistent production
Possible challenges:
- genetic engineering costs
- purification
- contamination control
- regulatory requirements
Common Mistake: Genetic Engineering Creates Genes From Nothing
Scientists generally work with:
DNA sequences and genetic information.
They may isolate, copy, synthesize, modify, or combine DNA sequences.
The process is based on manipulating genetic information.
Common Mistake: The Plasmid Is the Bacterial Chromosome
A plasmid is usually a small DNA molecule separate from the main:
bacterial chromosome.
Plasmids are useful vectors because they can be manipulated and maintained inside bacteria.
Common Mistake: The Bacterium Becomes Human
Adding a human gene to a bacterium does not make the bacterium:
human.
It remains a bacterium containing additional genetic information.
Common Mistake: Genetically Engineered Microorganisms Are Always in the Final Product
Often the microorganism is simply the:
production system.
The desired protein or chemical is extracted and purified.
The production organism may not be present in the final product.
Common Mistake: All Genetically Engineered Organisms Have the Same Risks
Risk depends on:
- organism
- inserted gene
- environment
- product
- containment
- intended use
Each application must therefore be evaluated:
individually.
Common Mistake: Genetic Engineering and Cloning Are the Same
Genetic engineering modifies genetic material.
Cloning produces genetically identical or nearly genetically identical copies of DNA, cells, or organisms.
The concepts can overlap in biotechnology, but they are:
not the same process.
Check Your Understanding
1. Define genetic engineering.
2. Why are microorganisms useful in genetic engineering?
3. What is a gene?
4. Describe the relationship between DNA, RNA, and proteins.
5. What is recombinant DNA?
6. What is a plasmid?
7. Why are plasmids useful in genetic engineering?
8. What is a vector?
9. What does a restriction enzyme do?
10. What does DNA ligase do?
11. What is bacterial transformation?
12. Why are marker genes useful?
13. What happens when an inserted gene is expressed?
14. Why are engineered microorganisms grown in bioreactors?
15. Give four conditions that may need to be controlled in a bioreactor.
16. Why must useful proteins be purified after microbial production?
17. Describe how genetically engineered microorganisms can be used to produce human insulin.
18. Give two advantages of recombinant insulin production.
19. Why might yeast sometimes be used instead of bacteria?
20. Name two medicines or medical products that can involve recombinant biotechnology.
21. How can genetically engineered microorganisms contribute to vaccine production?
22. What is recombinant chymosin?
23. How is genetic engineering used in industrial enzyme production?
24. How could genetic engineering improve biofuel production?
25. What is metabolic engineering?
26. What is meant by a microbial cell factory?
27. Compare genetic engineering with selective breeding.
28. Explain the difference between genetic engineering and fermentation.
29. Give four benefits of genetically engineered microorganisms.
30. Why can microbial production reduce dependence on animal tissues?
31. Why is containment important?
32. What environmental concerns could arise from releasing genetically engineered microorganisms?
33. What is horizontal gene transfer?
34. Why have antibiotic resistance marker genes raised concerns?
35. Why must recombinant medicines undergo quality control?
36. Why might genetic engineering produce unintended biological effects?
37. Give two ethical questions associated with genetic engineering.
38. Explain why different genetic engineering applications require different risk assessments.
39. Describe one example of microbial genetic engineering that affects everyday life.
40. Evaluate the use of genetically engineered microorganisms by considering both their potential benefits and their possible risks.
Key Terms
- Genetic engineering: Deliberate modification of an organism's genetic material using biotechnology.
- Gene: DNA sequence that contributes to a functional product, often a protein.
- Recombinant DNA: DNA created by combining genetic material from different sources.
- Plasmid: Small DNA molecule found separately from the main bacterial chromosome.
- Vector: DNA molecule used to carry genetic information into a cell.
- Restriction enzyme: Enzyme that cuts DNA at particular sequences.
- DNA ligase: Enzyme that joins pieces of DNA.
- Transformation: Uptake of external genetic material by a cell, particularly bacteria.
- Gene expression: Use of genetic information to produce RNA or protein.
- Recombinant protein: Protein produced using recombinant DNA technology.
- Bioreactor: Controlled vessel used for biological production.
- Insulin: Protein hormone regulating blood glucose.
- Chymosin: Enzyme used in cheese production that can be manufactured using genetically engineered microorganisms.
- Antigen: Substance recognized by the immune system that can trigger a specific immune response.
- Metabolic engineering: Modification of cellular metabolic pathways to increase or alter production.
- Microbial cell factory: Microorganism engineered or selected to manufacture useful products.
- Horizontal gene transfer: Movement of genetic material between organisms other than by parent-to-offspring inheritance.
- Downstream processing: Recovery and purification of a product after biological production.
- Containment: Measures used to prevent organisms or biological materials from escaping controlled conditions.
Key Takeaways
- Genetic engineering involves deliberately modifying genetic material.
- Microorganisms are useful because they reproduce rapidly and can be grown in large numbers.
- A useful gene can be introduced into a microorganism so that the cell produces a desired protein.
- Plasmids are commonly used as vectors in bacterial genetic engineering.
- Restriction enzymes can cut DNA, while DNA ligase can join DNA fragments.
- DNA containing genetic material from different sources is called recombinant DNA.
- Genetically modified bacteria can be identified, selected, and grown in bioreactors.
- The basic relationship DNA → RNA → protein explains how an inserted gene can lead to production of a useful protein.
- Genetically engineered microorganisms can contribute to the manufacture of insulin, growth hormone, vaccine components, enzymes, and other useful substances.
- Recombinant human insulin is a major example of medical biotechnology.
- Yeast as well as bacteria can be genetically engineered for protein production.
- Recombinant chymosin is an example of microbial genetic engineering used in food production.
- Genetic engineering and industrial cultivation often work together: genetic engineering creates the production strain, while cultivation produces large quantities of the desired substance.
- Useful proteins generally require extraction, purification, and quality testing.
- Genetically engineered microorganisms can provide efficient and consistent large-scale production.
- Genetic engineering can reduce dependence on animal-derived materials.
- Potential concerns include environmental release, gene transfer, contamination, unintended effects, cost, and ethical questions.
- Genetically engineered microorganisms must be appropriately contained and monitored.
- Risks and benefits depend on the specific organism, gene, product, environment, and application.
- Microbial genetic engineering connects DNA biology, microbiology, medicine, food production, biotechnology, and industrial manufacturing.