Microorganisms are all around us. They can be on the table, in the water, in the air, and even on your skin. While most microorganisms are harmless, some can cause disease. Because of these pathogenic, or disease-causing, microorganisms, measures to control their growth are needed.
If your students have microbiology labs, they work with microorganisms on a regular basis. After each experiment, decontamination is necessary to prevent the uncontrolled spread of microorganisms in the lab and outside. Controlling microbial growth is an essential set of skills in microbiology that students need to acquire.
But for students learning microbial growth control for the first time might find the lessons daunting. But there are many ways to make it more engaging and approachable. Read on to find out how.
First of all, let’s take a look at why students find it challenging to learn how to control microbial growth. Here are the top three reasons experienced by both students and teachers.
As the name suggests, microorganisms exist on the micro-scale. Students will need a microscope to see them. It’s hard for them to appreciate things they cannot easily see. Moreover, microorganisms can reach problematic levels even before they form colonies, biofilms, or byproducts that can be seen with the naked eye. Even if there seems to be nothing there, microorganisms can already number in the millions.
Microorganisms are hardy creatures, and a lot of them can survive conditions that are less than ideal for larger life forms. Controlling microbial growth requires means that may cause injury to students if they are not careful. Also, if these techniques are not done meticulously, some microorganisms may remain. Once they propagate, they will cause trouble again.
Decontamination and sterilization methods that involve heat and chemicals are particularly prone to accidents. If students become careless, they may experience burns, allergies, or irritation.
Microbial control with antibiotics is safer, as it does not involve heat or strong chemicals. But there is still the danger of unintentionally causing the spread of antibiotic-resistant strains. If students are dealing with a potentially pathogenic species, antibiotic resistance will pose a threat to their health.
In the process of controlling microbial growth, students may inadvertently come into contact with the microorganisms themselves. If their decontamination techniques are not thorough enough, they may develop diseases from the microorganisms they picked up in the lab.
Based on the difficulties students have when studying how to control microbial growth, here are five tips for educators to make the topic more interesting. Each piece of advice addresses a particular challenge that students face.
If teaching microbial growth control can be made more approachable for students, they will gain mastery more quickly. They will also recall key concepts more easily when they take higher biology, microbiology, or medicine courses.
Your skin, the ground, and pretty much every surface you come into contact with are teeming with microorganisms. Normally, this is not an issue; your immune system takes good care of most of the pathogens you come across. But there are situations where the microbial load (the number of infectious pathogens) needs to be carefully controlled.
In patient care scenarios, for example, careful cleaning procedures are performed to control the spread of pathogens. While this may sound highly technical, the processes start out similarly to cleaning your kitchen surfaces or bathroom.
If microbial growth is not controlled, serious consequences can arise. Some of these may even prove fatal. One extreme example is a condition called septicemia, which is a systemic infection of the bloodstream by pathogenic microorganisms.
Pictures, diagrams, illustrations, and videos are helpful in making students better comprehend concepts regarding microbial growth control. Moreover, students can better understand microbiological techniques when their learning is aided by graphics, animations, and videos.
Videos, in particular, can make teaching practical concepts easier. Students can replay video demonstrations as many times as they need until they have a good grasp of the concepts they need. They can learn how to use an autoclave, perform antibiotic susceptibility assays, and other procedures by watching step-by-step instructions. By the time they work on a real lab bench, they already know everything they need to do.
Interactive simulations are even better. They let students manipulate lab instruments and reagents virtually, so it’s as if they’re doing the real thing. If they make mistakes, there is no risk to themselves or others. Once they master the technique in the virtual world, they will be more confident as they perform actual experiments in the real lab. The image below is from Labster’s simulation entitled Control of Microbial Growth: Explore decontamination and selective toxicity.
Discover Labster's Control of Microbial Growth virtual lab today!
Before students can properly learn how to control microbial growth, they need to have mastered the basics. It is a good idea to ensure that students have thoroughly learned fundamental concepts, such as the ones below:
There are many methods of microbial control, including sterilization, irradiation, and using antimicrobial agents. Each method has a different level of control and uses different equipment and reagents. Below is an overview of each one.
Sterilization is a type of decontamination that leaves no microbial load on an item. In other words, there are zero bacteria, fungi, spores, or even proteins present to transmit infection. Sterilization is the highest level of decontamination, and it is valuable in healthcare settings.
Different sterilization methods include wet heat (steam), dry heat, irradiation, and chemical sterilization. The gold standard and most effective way to sterilize lab equipment is through wet heat, where instruments and reagents are put inside an autoclave. The autoclave generates intense heat and pressure (121ºC, 15 psi) that can destroy all infectious material.
Some lab instruments and reagents may be damaged by heat and pressure, so they cannot be placed in an autoclave. For these purposes, dry heat (baking) is used. The temperature and cycle time is higher than an autoclave (160-190ºC for up to two hours).
Irradiation is also an effective method of microbial control. Surfaces exposed to ultraviolet (UV) light are effectively disinfected. Exposure to UV light is a common method of disinfecting cell culture hoods. UV light does not generate much heat, making it useful for disinfecting heat-sensitive items.
Antimicrobial agents can be used to control microbial load without heat or radiation. They can have general effects, destroying any microorganism, or they can have specific targets. Chemical disinfectants like 70% ethanol, 10% hypochlorite bleach, or 0.2% glutaraldehyde can be used to clean lab equipment and surfaces. They are indiscriminate, killing all microorganisms they come in contact with.
Antibiotics, on the other hand, are selectively toxic. Different antibiotics act on specific kinds of bacteria, targeting different parts of bacterial cells.
Antibiotic sensitivity assay (Image source: Wikimedia Commons)
Virtual lab simulations are excellent tools for teaching control of microbial growth. Labster is determined to deliver fully interactive advanced laboratory simulations that make use of gamification elements like storytelling and scoring systems while exposing students to an immersive, realistic, 3D environment.
Check out this simulation called Control of Microbial Growth: Explore decontamination and selective toxicity at Labster. This virtual lab allows students to perform decontamination and antibiotic selection in a safe, computer-generated environment. With this, students will gain the confidence to eventually perform the procedure on their own in an actual lab.
The image below is an example of what students can explore in the simulation.
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