Introduction to Controlling Microbial Growth - Online Tutor, Practice Problems & Exam Prep

Introduction to Controlling Microbial Growth

In this video, we're going to begin our introduction to controlling microbial growth. It's actually really important for humans to be able to control the growth of microbes because it is critical to human health and a wide variety of other processes. For example, the manufacturing of specific types of products and even specific types of foods that you may eat on a regular basis. Uncontrolled microbial growth is a problem because it can lead to increased risk of disease and the spoilage or reduced quality of specific types of products. Therefore, it is crucial for humans to be able to control microbial growth.

It turns out that there are many different types of processes that humans can use to limit the growth of microbes. These processes used to control or limit microbes can either be physical processes, chemical processes, or a combination of both. Moving forward in our course, we're going to discuss various physical and chemical processes used to control microbial growth.

Because there are so many different microbial growth control methods, it is also vital for scientists to know how to select a specific process for controlling microbial growth. Selecting a process depends on many variables, including the circumstances and the level of control required. Later in our course, we'll also talk more about the process of selecting the appropriate microbial control method.

If we take a look at our image below, we can see a map of our lesson on controlling microbial growth. This image serves as a map or an outline of our lesson moving forward. Notice that the title here is 'Microbial Growth Control Methods.' The methods are broken up into being either physical methods, such as temperature and filtration, or chemical methods, such as liquid chemicals and gas chemicals. Right in the middle, we have irradiation, which is a combination of both physical and chemical, since irradiation can lead to direct damage but can also result in the formation of other chemicals causing damage to the cells. We'll discuss each of these different types of microbial growth control methods extensively as we move forward in our course.

Starting with the leftmost branches first, we will cover physical methods of chemical control, including controlling temperature through methods like moist heat, dry heat, or refrigeration, and filtration, such as filtering liquids and air. Then, we'll discuss irradiation, a combination of physical and chemical methods, which can cause direct damage or lead to the formation of damaging chemicals. Types of irradiation we will cover include ionizing radiation and non-ionizing radiation, such as UV light. After covering the physical methods and irradiation, we will move on to the chemical methods in our lesson. We'll discuss the use of liquid chemicals first, then gaseous chemicals.

This introduction to controlling microbial growth sets the stage for our future discussions, where we'll dive deeper into these methods and also talk about how to select the appropriate method. This concludes our introduction, and we'll be able to apply these concepts and learn more as we move forward. I'll see you all in our next video.

Why is it important to human health and wellbeing that we control microbial growth?

• A. Uncontrolled microbial growth can lead to increased risks of disease and infection.
• B. Uncontrolled microbial growth can lead to spoilage of food products.
• C. Uncontrolled microbial growth can lead to contaminated experiments.
• D. All of the above.

Physical methods used to control microbial growth include all of the following except?

• A. Refrigeration.
• B. Air filtration.
• C. Liquid chemical disinfectants.
• D. Steam (moist heat).

Terminology of Microbial Growth Control

So when it comes to controlling microbial growth, there's actually a lot of terminology that is used. In this video, we're going to introduce some of the terms of microbial growth control. There are several terms used in relation to controlling microbial growth, including decontamination, sanitization, disinfection, sterilization, and preservation.

The first term on this list is decontamination. Decontamination is a broad and general term that refers to the overall reduction of the number of pathogens or disease-causing agents to a safe level. The next term is sanitization. Sanitization is a more specific term that refers to cleaning and reducing pathogens in order to meet accepted public health standards to help minimize disease. Things that have been sanitized are going to have the appearance of being clean, thereby reducing pathogens similar to decontamination, except sanitization also meets accepted public health standards.

Next, we have disinfection. Disinfection is the elimination of most, but not all, pathogens. Through disinfection, most pathogens are eliminated, but it is possible for some viable or living microbes to remain, especially those that are resistant, such as endospores. This fact distinguishes disinfection from sterilization, which is the elimination of all microbes, except for prions, which are proteinaceous infectious agents. Sterilization eliminates all other microbes such as microorganisms, viruses, and even resistant endospores.

The last term we discuss is preservation. Preservation is the process of delaying, rather than killing cells. This process delays the spoilage of perishable products, usually by delaying the growth of microorganisms. Perishable products are items that are likely to go bad quickly. Preservation delays the spoilage process instead of eliminating it.

Moving forward in our course, we'll be able to talk about some methods of preservation. Starting with decontamination, which, as mentioned before, is a broad and general term that refers to the reduction of the number of pathogens to a safe level. This term can be used broadly in many different scenarios. Sanitization reduces the number of pathogens specifically to meet public health standards, which helps minimize the spread of disease. Objects that have been sanitized, such as sanitized tables, reduce the number of pathogens to public health standards, thus being less toxic to humans and having the appearance of being clean.

Then we have disinfection, which again is the elimination of most pathogens. A disinfectant, used in a spray bottle by a scientist, eliminates most pathogens, although some are still capable of surviving. Disinfectants are slightly more toxic to humans in comparison to sanitizers. For sterilization, it refers to the elimination of all microbes, except for prions, using methods such as radiation. All microbes are eliminated in sterilization, which is a critical distinction from disinfection, where some microbes might survive. Finally, in preservation, we use techniques such as refrigeration to delay spoilage of perishable items like food.

As we progress in our course, we will primarily discuss methods of controlling microbial growth through disinfection and sterilization, but we will also touch on preservation techniques. This concludes our brief introduction to the terminology of microbial growth control, and we'll be able to get some practice applying these concepts as we move forward. I'll see you all in our next video.

Hierarchy of Microbial Growth Control Terminology

In this video, we're going to talk about the hierarchy of the microbial growth control terminology that we introduced in our last lesson video. And so notice on the left over here we're showing you a pyramid, and these terms over here are focused on killing microbes or the elimination of microbes. And notice that decontamination is the very first term towards the top of this pyramid, and that's because recall decontamination is a very broad or general term, which is why it's up here towards the top of our pyramid showing that it is a broad term. And it refers to the reduction of pathogens to a safe level.

Next, what we have is sanitization, which is really a form of decontamination, but it is specifically going to allow for meeting public health standards and giving the appearance of the object being clean. And so because it's meeting public health standards, it is going to be somewhat of a more specific term than decontamination is, and so that's why it's given a more narrow region of the pyramid here because it's a more specific term.

And then, next what we have is disinfection, which recall disinfection is going to eliminate most pathogens. However, it is possible for some pathogens to survive. And so notice that most pathogens are being eliminated or killed here, but some pathogens like this little guy over here may still survive after disinfection.

And then the last term that we have here in this pyramid is sterilization. And sterilization is going to eliminate all pathogens, all microbes, except for prions. That's the only exception there. But everything else is going to be completely eliminated through sterilization techniques. And so you can see that the percentage of microbes that survive is actually decreasing as we go from top to bottom in this pyramid. And so, notice that with sterilization, because it's towards the bottom here, there's going to be a very small percentage of microbes surviving, practically 0% surviving, through sterilization.

Then notice that off to the right, what we have is processes that delay microbial growth. And so when we talk instead of killing microbes, there's also the ability to delay the growth of those microbes. And really, that is what preservation techniques are going to do. Instead of actually killing microbes, preservation techniques are going to delay the growth of microbes.

And so, hopefully this image here helps with your understanding of these microbial growth control terminology. And, we'll be able to get some practice and learn more about these terms, and different microbial growth control procedures as we move forward. So I'll see you all in our next video.

What is the main difference between preservation and sterilization?

• A. Preservation does not kill microbes but delays microbial growth. Sterilization kills all microbes, except prions.
• B. Preservation preserves food by killing all microbes present in or on food. Sterilization kills most pathogenic microbes.
• C. Preservation reduces pathogens to meet health standards. Sterilization kills all microbes.  
• D. Preservation kills all microbes except prions. Sterilization kills all microbes, including prions.

Situations Warranting Different Levels of Microbial Growth Control

In this video, we're going to talk about some different situations that warrant different levels of microbial growth control. And so the methods that are used for microbial growth control vary greatly depending on the specific situation and the specific level of microbial growth control that is needed. And so really the most important message that we're trying to communicate in this video is something that may seem pretty obvious. And that is that the control measures that are used on a regular basis at your home may not be adequate enough for a surgery room in a hospital. And so once again, different situations or different scenarios are going to require different levels of microbial growth control. And so down below in our image, we're showing you 5 different situations or scenarios that can require different levels of microbial growth control.

The first situation or scenario is going to be your daily life. And so things like washing, using soaps and detergents, and also cooking and refrigerating foods are all methods to be able to control microbial growth. And so you can see washing hands, and doing laundry with soaps and detergent, and cooking, and refrigerating your foods are all methods that you can use at your home to control microbial growth. However, in a different setting such as a hospital setting, there are going to be different measures to control microbial growth. For example, sterilizing surgical equipment and operating rooms in order to avoid what are known as healthcare-associated infections, or HAIs for short.

Healthcare-associated infections or HAIs are pretty much what they sound like. These are infections that a patient can get in a healthcare setting if the hospital does not control the microbial growth appropriately. And so it's really important for hospitals to make sure that they create a sterile field for surgery in surgery rooms or operating rooms. And, it is also important that they use steam, using instruments such as autoclaves, to sterilize their surgical tools so that they don't accidentally cause a healthcare-associated infection or an HAI in a patient. And so the microbial growth control methods used in a hospital need to be a lot more stringent, a lot more rigid, a lot more powerful than the control methods that you may use in your daily life.

Now another setting that we have here is food production facilities that are going to use physical and chemical methods for food preservation, helping to delay the spoilage of perishable objects such as food products. And so here we're showing you an image of how pasteurization can be used in milk to kill microbes found in milk. And here we're showing you some vegetables that have been irradiated, some fruits and vegetables that have been irradiated or undergone radiation. And so this is a symbol here that represents food that has undergone irradiation. And once again, irradiation may be something that you do not use in your typical daily life. So every scenario may require a different microbial control method.

The fourth one that we have down here is going to be the water treatment facilities, which are going to need to use specific disinfectants, and they will need to disinfect the drinking water to prevent waterborne illnesses. And so here is a water treatment plant in Deer Island. And once again, the microbial control methods that they use in this water treatment plant may be different than the control methods that they use in any of these other situations.

And then last but not least the fifth scenario that we have here are going to be the laboratories. And the laboratories, such as scientific laboratories, microbiology laboratories, biology laboratories, also need to sterilize equipment in many scenarios. They sterilize their equipment and they can use what is known as aseptic technique, which is a set of techniques that help to prevent contamination. And so down below here we're showing you a scientist in a COVID-19 lab studying COVID-19, the virus that causes COVID-19. And they're using PPE or personal protective equipment that protects the scientists. So notice that they have this coat and they're using gloves and they have a mask and goggles. And so these are also ways to help control microbial growth to make sure that it's not being spread into other areas, that it's being contained in a specific region. And then over here what we're showing you is UV light, ultraviolet light, which can be used to help kill microbes in a lab and prevent contamination.

Basically, what we've shown you here are 5 different situations that warrant different levels of microbial growth control. And so that is definitely going to be a consideration in selecting the appropriate control method. And so we'll be able to learn a lot more about selecting a microbial control method as we move forward in our course. But for now, this here concludes our lesson and we'll be able to get some practice moving forward. So I'll see you all in our next video.

Which of the following concerning the varying levels of microbial control is false?

• A. We clean and sanitize our homes to reduce the number of microbial pathogens.
• B. Hospitals attempt to sterilize and kill all microbes in rooms and on tools to prevent infection.
• C. Pasteurization and irradiation are common microbial growth control methods used in food production.
• D. Laboratories sterilize media and tools to prevent contamination of their experiments.
• E. All of the above are true.