Temperature Requirements for Microbial Growth

in this video, we're going to begin our lesson on temperature requirements for microbial growth. And so as you may already know, different microbial species have specific temperature ranges in which these microbes are able to grow. And so these temperature ranges are going to include minimum and maximum growth temperatures. And so if the temperatures are too cold or if the temperatures are too hot, then the microbes may not be able to grow. Now, cardinal temperatures are referring to characteristic temperature values that define the specific ranges, temperature ranges in which a microbe can actually grow. And so the cardinal temperatures are going to include a minimum temperature. And of course the minimum temperature is going to be the lowest possible temperature that an organism can actually grow at now. Usually the minimum temperature is not going to be the best growth. It will usually be some form of ineffective growth at the minimum temperature, then there is the optimal temperature and the optimal temperature is going to be the best temperature for an organism to grow where the organism is able to multiply and grow most rapidly. And so the optimal temperature is the temperature that is going to be best suited for that particular organism. And then the cardinal temperatures are also going to include a maximum temperature. And the maximum temperature, of course, is going to be the highest temperature that an organism can grow at. And so once again, the maximum temperature is typically not going to be the best or the optimal temperature. The maximum temperature typically only allows for ineffective growth. And so if we take a look at our image down below, we can get a better understanding of cardinal temperatures, which again, is going to include a minimum temperature, an optimal temperature and a maximum temperature. And so notice that in this graph that we have down below. Over here, on the left hand side, what we're showing you is the cell growth rate. And so this is showing you how fast the cells are able to grow. Uh having a low value on this Y axis means that the cells are growing really really slowly and so they're not growing very well. However, being high, having a high value on the Y axis corresponds with high self cell growth. And the cells are able to grow at a very fast rate. And then notice that down below what we have is the specific temperature. And so notice that this curve has a curve that somewhat looks like this uh bell curve right here and what we have is a minimum temperature, which is going to be the coldest possible temperature that will allow for cell growth. But notice that the cell growth is not going to be very effective at the minimum temperature in most cases, uh then somewhere in between the minimum temperature and the maximum temperature is the optimal temperature. The optimal temperature is going to be the specific temperature value that allows for the highest amount of growth, the highest growth rate. And so the optimal temperature is going to correspond at this particular region on the X axis. And then of course over here, what we have is the maximum temperature, which is the highest possible temperature that allows for cell growth. But notice once again, in most cases, the maximum temperature is not going to allow for very effective cell growth. In fact, it's quite ineffective here in this image. And so this year concludes our lesson on temperature requirements for microbial growth and we'll be able to get some more practice applying these concepts and learn more about microbial growth as we move forward in our course. So I'll see you all in our next video.

Which bacterial culture will have the highest growth rate?

• A. E. coli bacteria being grown between the temperatures of 37°C & 40°C (optimal temperatures).
• B. E. coli bacteria being grown between the temperatures of 15°C & 20°C (minimum temperatures).
• C. E. coli bacteria being grown at 45°C (maximum temperature).
• D. E. coli bacteria would grow at the same rate at any temperature.

in this video, we're going to begin our lesson on the classification of microbes by growth temperature. And so microbes are actually classified into five groups based on their cardinal temperatures. Which recall from our last lesson video is referring to the growth temperatures from the minimum growth temperature up to the maximum growth temperature for these cells to survive. And so if we take a look at this image down below, notice that we're showing you a graph where on the Y axis it has the cell growth rate where the higher the Y axis is the higher the rate of growth for those cells and the lower the Y axis is, the lower the growth rate is for those cells. And then on the X axis. What we have is the temperature in degrees Celsius increasing from left to right. And so notice that we have these five different curves here in this graph where each of these curves corresponds to a different group of microbes. And so the first group of microbes that we have is the one that's on the far left over here in light blue, which is referring to the psy crow files. And so psy crow is actually a route that means cold and file is a route that means loving. And so these are organisms that love extremely cold temperatures. And so you can see that they can thrive from temperatures anywhere between negative 10 degrees Celsius and about 15 degrees Celsius. And the optimum growth rate is going to be at a temperature somewhere between zero and 10 degrees Celsius. And so these psych profiles really really do grow best and really cold environments such as for example, icebergs. Now the next group that we have here is the one in Green, which is referring to the psy crow troughs. And once again psy Crow is a route that means cold and troughs is actually a route that's referring to nutrients. And so this can help remind you of refrigerators since refrigerator store a lot of the nutrients that you and I consume. And so these psycho troughs tend to live inside of cool temperatures and uh they can survive from temperatures anywhere between uh negative tennis degrees Celsius all the way up to about 35 degrees Celsius. But notice that the optimum growth temperature for these psycho trough is somewhere between 20 and 30°C. And so they survive in cool environments like again, refrigerators. Now, the next group that we have here is the one here in purple, which is referring to the Miso files. And so as the scientists here is saying, Miso files grow on me and so humans have body temperatures right around 35 ish degrees Celsius. And so notice that the optimum growth temperature for these miso files is right around 35 degrees Celsius. And so these miso files can survive anywhere from between 10 degrees Celsius up to over 40 degrees Celsius. But once again, miso files are going to be somewhat in the middle here and they are the middle group uh for these five groups that we see here. Now, the next group that we have here is the curve that is here in orange, which is referring to the Thermo files. And the Thermo files survive and much warmer and hotter temperatures such as hot springs for example. And thermo files can survive from anywhere between 40 degrees Celsius up to Over 80°C. But the optimum growth temperature Is pretty high, somewhere around 70°C or so. Then the last group that we have here is the one that is in dark red over here, which is referring to the hyper Thermo Files. And so, hyper is a route that's referring to very high. And so, hyper thermal files can survive extreme amounts of heat and so notice that they can survive in temperatures from About 70 ISH, 75°C all the way up to about 120°C. And notice that their optimal growth temperature is extremely high, right around 100°C. And so these hyper thermal files can survive and hydrothermal vents deep underneath the ocean where the temperatures are extremely hot. And so these are the five classes of microbes that are grouped based on their growth temperatures. The psych profiles, the psycho troughs, the Meso files, the thermal files and the hyper thermal files. And so 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

What is the optimum growth temperature of mesophiles?

• A. 0-10 °C.
• B. 0-20 °C.
• C. 20-30 °C.
• D. 50-60 °C.

A thermophile or a hyperthermophile species would have thermo-stable proteins & enzymes that…

• A. Resist denaturation in extremely high temperatures.
• B. Perform more efficiently in cool temperatures.
• C. Easily denature in extremely high temperatures.
• D. Have a particular amino acid sequence that restricts bond formation.

in this video, we're going to talk about a silly way to help you guys memorize the classification of microbes by growth temperatures from the lowest growth temperature to the highest growth temperatures. And so were called from our previous lesson videos that psych profiles site grow troughs. Mezzo files, Thermo files and hyper thermal files are those five groups of microbes organized by their growth temperatures. And recall that psy crow files grow at the coldest temperatures. Whereas hyper thermo files grow at the hottest growth temperatures. And so really all you need to do to remember the order of these five groups is to remember the following phrase which is psycho fill, psyched my temperate horse. And so notice that we've got psycho Phil over here saying he's crazy and notice he's in the cold temperatures and he's psyching out this horse over here, notice he's like ah and he is a temperate horse here. Clearly with these, this thermometer trying to cool down his temperatures. And so if you can remember cycle feel psych my temperate horse, then that could help you remember that psych grow files are going to be the coldest grow at the coldest temperatures followed by psy crow troughs, then we have miso files, then thermo files. Um, and then last but not least what we have are the hyper Thermo files. And so once again, this is just a silly way that could possibly help you memorize the order of these groups from lowest to highest growth temperatures. And so this year concludes our brief lesson on this and we'll be able to get some practice as we move forward. So I'll see you all in our next video.

The temperature of a human body is anywhere from 35-40C. What type of pathogen can infect humans?

• A. Thermophile.
• B. Hyperthermophile.
• C. Psychrophile.
• D. Mesophile.