Chemical Methods to Control Microbial Growth - Video Tutorials & Practice Problems
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Chemical Methods to Control Microbial Growth
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3m
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in this video, we're going to begin our lesson on chemical methods to controlling microbial growth. And so in addition to the physical methods of controlling microbial growth that we already covered in our previous lesson videos recall that there are also chemical methods to controlling microbial growth. Now there are actually several different types of chemical agents that can be used for controlling microbial growth, including the following. For that we have numbered down below. And so the first is going to be a sanitizer. And so a sanitizer is a chemical that as its name implies, is going to be used to sanitize. And that means that it's going to be killing mainly bacteria in order to meet public health standards. And also recall that sanitization includes this effect of appearing to be clean. And so uh sanitizers are also going to help with that appearance of making the object appear clean. Now the next type of chemical agent that we have here are disinfectant. And disinfectants are also sometimes referred to as german sides or microbicides. And so disinfectants or german sides or microbicides are all synonymous with each other, and they are referring to chemicals that are used to disinfect inanimate or non living objects. Now antiseptics, the third one that we have here is going to be a specific type of disinfectant, but this is going to be a type of disinfectant that can be safely used on living tissue. And so disinfectants are implied that they're going to be used on inanimate or non living objects. Whereas antiseptics are specific types of disinfectants that are safe to be used on living tissues. Uh Then last but not least, we have sterilizers and sterilizers are going to be chemicals that sterilized by destroying all microbes, of course, except for prion. Since those are microbes that are resistant to sterilize. And this includes killing off all of the endo spores Which are typically resistant to all of these other three types. And so sterilizers are the only one listed here that can are powerful enough to actually kill endo spores. And so if you take a look at this image down below, notice at the top what we have are the sanitizers which again are going to be used for sanitizing and helping things to appear clean. And they're going to be meeting public health standards, allowing you to be able to use sanitizers on your hands right before you eat. Uh then what we have are the disinfectants which recall disinfectants are also sometimes referred to as german sides or microbicides. And these are going to be used to disinfect inanimate objects. And so that means that they're going to kill the vast majority of pathogens. But some viable pathogens may still be able to survive. Antiseptics are specific types of different disinfectants that are able to be used on living tissue. So if you get a cut or something like that, you're able to use antiseptics to help uh and use that on your own skin and, you know, living tissues and then last but not least towards the bottom here, what we have are the sterilizers which are going to pretty much kill all of the living organisms. Um and it will kill all microbes except for brian's. And this includes the endo sports, so it will kill end of sports. And so this year concludes our brief introduction to the chemical methods of controlling microbial growth. And as we move forward in our course, we're going to get to learn a lot more about different types of chemical methods. And so I'll see you all in our next video.
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concept
Types of Disinfectants
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5m
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in this video, we're going to talk about the types of disinfectants. And so recall from our last lesson video, we said that disinfectants are also sometimes referred to as microbicides or as germ asides. And these disinfectants are really just chemicals that are used to disinfect inanimate or non living objects. Now these disinfectants can be grouped based on whether or not they kill or if they inhibit the microbes and they can also be group based on the types of microbes that they are most effective against. Now the suffix side is a suffix that means to permanently kill. And so bacteria sides are going to be chemicals disinfectants that will kill bacteria, fungus sides are disinfectants that kill fungi and so you can see how the root bacteria indicates that it kills bacteria and the roots side indicates that it is killing these bacteria and the same goes for the fun. Besides the root fun guy indicates that fungi are being affected and once again, the route sides indicates that it's killing those fun guy. Now on the other hand, the suffix static is a Suffolk. That means to reverse a ble inhibit. And so that means that it can inhibit the growth of those microbes, but if somehow that disinfectant could be removed then it could allow for the reverse ability and allow the microbes to continue to grow. And so for example, bacteria statics are going to be disinfectants that inhibit bacterial growth. Once again, the bacteria route indicates that bacteria are being affected. And the static route indicates that there is inhibition of growth rather than killing. And so that's something important to keep in mind that just because their growth is inhibited does not necessarily mean that they are dead. Now, fungus statics are going to be disinfectants that inhibit fungal growth. And once again, the fun guy here indicates that Fun Guy are being infected. And these static Suffolk's indicates that there is inhibition of growth rather than killing. And so if we take a look at our image down below we can get an even better understanding of the difference between bacteria sidles and bacteria of statics and so on the left hand side what we're showing you is a bacteria side uh and a bacteria side. Once again it's going to be a disinfectant that will kill bacteria. And so notice that we're showing you this plot. And on this plot on the Y axis we have the log of the number of cells. So the higher the Y. Value, the more cells there are, the lower the Y. Value the less cells there are. And then on the X. Axis what we have is the time. And so notice initially that there are very little cells. But then these cells are starting to grow um as they normally would. But then notice that this particular time point right here is the time for the addition of the bacteria side. And once the bacteria side is added the bacteria side will begin to kill these cells. And so notice that the number of viable cells, the number of living cells is starting to drop down because those cells are being killed. And notice that the total number of cells is remaining the same here after the addition of the bacteria side. And then notice that even after removal of the bacteria side, if somehow the bacteria side were able to be removed, those cells have already been killed and so notice that the cells are not going to continue to grow. Now notice on the right hand side over here we're focusing on bacteria statics and bacteria statics will inhibit the growth of the bacteria rather than killed bacteria. And so notice that we have the similar plot down below, except notice that what the addition of the bacteria static notice that the number of viable cells remains constant and that the cells are not actually dying off. And so the number of viable cells remain constant. And so uh if it were possible to remove the bacteria static then those viable cells will continue to grow as they were before the addition of the bacteria static. And so that is something important to keep in mind. Once again, bacteria sides are going to kill the bacteria permanently kill them and the bacteria statics are going to only temporarily inhibit the bacteria until the bacteria static is no longer present. And so this year concludes our brief lesson on the types of disinfectants specifically um uh bacteria sides versus bacteria statics and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video
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Problem
Problem
_______________ inhibit the growth of bacteria & ____________________ kill bacteria.
A
Fungistatics; Fungicides.
B
Bacteriocides; Bacteriostatics.
C
Bacteriostatics, Fingicides.
D
Bacteriostatics, Bacteriocides.
E
Bacteriocides; Fungistatics.
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concept
Selecting the Right Chemical Agent
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4m
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in this video, we're going to talk about some considerations when selecting the right chemical agent. And so selecting a specific chemical agent for controlling microbial growth is actually a really complex process. And this is because there are many different things to consider when selecting the right chemical agent. One of the most important considerations is actually the fact that the chemicals should only target the microbes of interest without causing any unintended damage. And that is something that is really important to keep in mind that the chemical may be effective against the microbe. However, if it also causes unintended damage, that may not be the best chemical to use for this situation. And so down below we have a few other considerations when selecting chemical agents for controlling microbial growth. And so down below, we have a list of five considerations for selecting chemical agents. The first one that we have listed here is the activity of the chemical agent around organic matter. And recall that organic molecules are going to be molecules that contain carbon and hydrogen and all living organisms contain organic matter. And so organic matter can be found in things like soil, for example. And so sometimes if soil is present, the chemical agent which could be bleach or some other chemical agent may not be effective at performing uh its function. And so the presence of organic matter can be a problem for these chemical agents to work appropriately. And so this is definitely an important consideration for the scientists to make is what is the activity of the chemical around organic matter. Now, the second consideration that we have here is actually the chemical toxicity. Um and so the chemical may be very effective against microbes, but if that chemical is toxic to humans or toxic to some other form of life that we do not want to damage, then maybe the chemical is not going to be suitable. And so the chemical toxicity is a very important consideration to make, to make sure that we are only targeting the microbes without causing unintended damage. Now, the third uh consideration that we have here is actually the storage capabilities. Some chemicals require very specific types of storage where they need to be in refrigerators or they need to be in freezers. Others require by high pressures and other conditions as well. And so sometimes the storage capability of the particular chemical agent can be a limiting factor and can dictate what type of chemical should be used in the scenario. Now, the fourth consideration that we have here is actually the cost of the chemical agent. And so a chemical may be really effective against microbes. However, if that chemical is really, really expensive, then perhaps it's not the best chemical to use for this situation. And so the cost of the chemical is going to be a very important consideration when the scientist is selecting the chemical agent and then last but not least what we have is the environmental impact of the chemical agent. And so once again that chemical agent may be very effective at controlling microbial growth. However, if that chemical agent has uh can serve as a pollutant and it can cause damage to the environment, then perhaps that is not the best chemical agent to use. And so all of these are really important considerations that a scientist should make when selecting the chemical agent, and once again similar to the physical methods of of controlling microbial growth for the chemical methods. There is not a perfect chemical method that will work in every scenario. Each chemical method is going to have a set of advantages and a set of disadvantages, and the scientists must weigh the advantages and disadvantages and make all of these considerations here in order to select the appropriate method for the scenario. And so this here concludes our brief introduction to selecting the right chemical agent. And we'll be able to get some practice applying these concepts moving forward in our course. And so I'll see you all in our next video
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