Biotechnology and microbes
Biotechnology and microbiology offer an opportunity to undertake practical investigations. However, culturing microbes in the school laboratory is sometimes seen as risky. This list includes information that introduces students to biotechnology and includes suggestions for practical activities.
Students often think of microbes as solely being harmful and pathogenic. The activities will help to illustrate that many microbes do not cause harm to humans and indeed can be used to make useful products.
The final two resources in the list are aimed at teachers and technicians. They look at the techniques needed to maintain cultures without introducing contamination and link to a web site that addresses safety concerns. By using these links, it is hoped that teachers will be encouraged to undertake microbiology practical work.
Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.
Quick Guide: Micro-organisms in Industry
This guide was produced by the Triple Science Support Programme. It gives information on biotechnology to teachers who may not be expert in the topic.
The guide can be read in less than 10 minutes and it includes information on:
• How microorganisms are used in industry.
• Features of different types of microorganisms.
• Environmental issues around biofuel.
The guide is useful for teachers planning to deliver the topic for the first time. It could also be given to more able students as additional reading. In this context, questions could be developed to turn it into a comprehension-style exercise in class-time or for a homework.
Secondary: Introduction to Microbes
These materials are a good introduction to microbes and can be used to start the topic of biotechnology.
The presentation can be used to describe the images shown on the presentation but with the text removed. Students can add their own annotations. Discourage them from simply copying down the text on the slide but to put the information into their own words. This will help to practice for extended written answers. Revision cards are available in the materials.
Once the presentation and note-taking has been completed, their knowledge on microbes can be reinforced using the ‘Top-Trumps’ style card game supplied. Divide students into groups of three or four. Have the winner of each round use the cards to describe the winning microbe to the rest of the group. For example, does the microbe cause disease, does it have an industrial application and where does it naturally occur.
Biotechnology: Bacterial Language
Microbiological practical work is often overlooked in schools but the techniques used are valuable skills to learn and will enrich the curriculum. This practical activity sees students investigating how bacteria communicate. Cultures are grown at room temperature.
Full details of the equipment and media required are given in the materials.
Students can be given the information sheets and asked to plan one of the investigations. This can be in the form of a table which clearly shows the different cultures that they propose to set up and the information that the results will tell them. In this way, they will need to think about the combinations and controls before starting the practical manipulations.
A slope culture is one in which the agar is left to solidify at an angle in a screw-top glass bottle.
Growth media must be sterilised, and kept in aseptic conditions before use. Cultures must be sterilised before proper disposal. This can be achieved using an autoclave or an appropriate pressure cooker. CLEAPSS recommend a temperature of 121oC for 15 minutes as the minimum temperature and time to destroy microbe spores and cells. For further details about choosing an autoclave or pressure cooker see the leaflet at: http://tinyurl.com/ntvm7tf
Making human insulin
This is a very basic animation but the slides are clear and accessible. If you add your own commentary, it will help students to understand the process of genetic engineering of bacteria to produce human insulin. The stages covered are:
• Identification and isolation of the human insulin gene.
• Insertion of the insulin gene into a bacterial plasmid.
• Growth of the genetically modified bacteria to produce human insulin.
Insulin for human can also be obtained from animal sources (typically pig or cow pancreas). It requires purification and modification before it can be used. Students can be challenged to compare insulin produced by genetically modified bacteria with insulin for human use obtained from animal sources. What are the advantages of insulin from bacteria?
Upgrading Whey
This practical activity is a good demonstration of the use of immobilised enzymes in biotechnology.
The materials give a method for producing whey from milk. Students then use immobilised enzymes to produce glucose from the ‘waste’ whey.
This part of the procedure is fairly straight forward and requires students to follow a set of instructions. They immobilise the enzyme lactase in alginate beads which are placed inside a syringe barrel. As the whey is run over the beads, glucose is produced. Students use a glucose test strip to measure the amount of glucose produced. Before their use, test strips can be cut in two along their length to double the number of tests.
Once students have shown that glucose is produced, they can be challenged to optimise the process to see how to get the greatest yield of glucose. Factors that could be investigated include:
• Temperature of the syringe ‘reaction vessel.’
• Flow rate of whey solution.
• Density of beads.
• Pressure inside the syringe.
• Amount of enzyme.
• Longevity of the immobilised enzyme.
• Effects of storage on the activity of the enzyme beads.
Depending on time available, students can work in groups and present results to the class, to model how a research group would work. This is the type of activity that would be undertaken in industry where laboratory processes are scaled up to full production size.
Biofuels
Fermentation is an important process in biotechnology. The booklet contains a range of practicals and information.
This activity focusses onto the fermentation of sugar solution to produce bioethanol. Details can be found in the accompanying booklet. Look for activity A3 from page 10 and on page 27. Students sheets are on pages 36 and 37. Slide 8 onwards in part 2 of the presentation can be used to introduce the activity.
The fermentation is set up on week one and then ethanol is distilled off the following week.
You may want to give students a homework before the first lesson to revise respiration. Then run a quick ‘pop quiz’ activity prior to setting up the experiment.
The activity suggests leaving the flasks at 25oC. In practice, just leave the solutions in a warm room. Using bungs with bubble traps inserted, instead of cotton wool plugs, will allow the formation of carbon dioxide gas to be seen. This can be an additional learning point and help to link the process to anaerobic respiration.
Industrially, ethanol is increasingly being produced using genetically-modified bacteria. Fermentation of lignin (wood) as a source of carbohydrate is also being developed as this reduces the need to use a food crop for fuel production.
As an extension activity, or homework, students could write a discussion of the statement: Should food crops be used for fuel production? This will allow them to develop skills in extended writing and construction of an argument.
Useful Microbes for Secondary Science
This simple practical illustrates to students one of the uses of microbes in food production. They make a simple yoghurt and then examine the culture under the microscope. This is a good opportunity to develop skills in slide preparation and microscopy.
Students take observations before and after fermentation.
Although precautions are taken not to introduce contamination, tell students that the yoghurt should not be eaten or sampled. Food-producing facilities need to be inspected and are scrupulously clean. The school laboratory is neither.
The activity can be extended by having students plan investigations into factors such as the effects of temperature, starter culture volume or how storage conditions effect shelf-life of the product.
How could they test the quality of the yoghurt? Eating it is not an option, especially when testing shelf-life as the product will eventually become spoiled. Students can suggest objective measurements. If time and resources permit, the investigations can be carried out.
Aseptic Technique
This is a really good video for teachers or technicians who are not confident in the aseptic technique required to manipulate cultures without introducing contamination. The video shows a range of operations that could typically be employed in a school laboratory or preparation room. The correct procedures can then be demonstrated to students.
Remember to undertake a full risk assessment and consult school, CLEAPSS or local authority guidelines before undertaking any microbiological activities.
When using a flame to sterilise inoculating loops, remember to let it cool before using it to pick up microbes. Additionally, let the loop cool before putting it onto the bench top after it is sterilised following use. It is only necessary to briefly waft the top of an open bottle or flask through the flame to sterilise it.
With students, it is worth stressing that it is important to prepare for the procedures. Common mistakes include not having all the necessary equipment to hand. Also stress that items do not need to be left in the flame for prolonged periods of time. Finally, remind students that items need to be re-sterilised before they can be stored or disposed.
You should only use known cultures, from trusted sources and never culture samples taken from the environment or body. Only incubate cultures at room temperature and do not open petri dishes or containers once the culture has grown. Sterilise materials before disposal (minimum of 121oC for 15 minutes in an autoclave or pressure cooker).
Further information and materials can be found at the National Centre for Biotechnology Education ( http://www.ncbe.reading.ac.uk )
Microbiology online
This link is intended to support teachers and technicians who may not be familiar with the use of microbes in the classroom. The web site it points to has been produced by the Society for General Microbiology.
Go to the Teachers section and follow the link to the Safety information. This includes safety guidelines, risk assessment, good microbiological practice and spillage management.
Useful guidance for technicians can be found in the section on Preparation of media and cultures.