Microbes in the Environment Lab

Madison Bauman Professor Dinbergs BIO 235 March 26, 2018 Lab 8 Microbes in the Environment Purpose: The purpose of this lab is to describe why agar is used in culture media as well as to prepare nutrient broth and nutrient agar. One should also be able to compare bacterial growth on solid and liquid culture media. Upon completion, one should be able to describe the colonies morphology using accepted descriptive terms. Expected Results: In the environments that I sampled, the most growth on the nutrient agar I believe to see will come from my the swab of my mouth. Yes, I expect turbidity in the unsterilized nutrient broth that was incubated because the incubation will give the desired and correct results. Nutrient agar will provide more information on the variety of bacteria in the environment more than nutrient broth because the nutrient agar is a solid. The nutrient broth is a liquid and it would be difficult to see any sort of bacterial growth compared to the solid medium that nutrient agar possesses to offer a support for the bacteria to grow on. Results: Area Sampled: Inside mouth Incubated at 37 degrees Celsius 2 days Estimated Diameter Whole-Colony Appearance Margin Elevation Pigment Number of this Type 2 mm Circular Entire Flat Gray Roughly 7 Less than 1 mm Circular Entire Flat Gray About 30 1mm Circular Entire Flat Yellow 4 Area Sampled: Hair Incubated at 37 degrees Celsius 2 days Estimated Diameter Whole-Colony Appearance Margin Elevation Pigment Number of this Type 1 mm Circular Entire Raised Yellow Only 1 Area Sampled Car Keys Incubated at 37 degrees Celsius For 2 days Unfortunately, nothing grew on this plate. I believe there are a few reasons as to why there was bacteria present after 2 days. Since my car key is metal, I believe the growing conditions were not right for bacterial growth. The metal is cold and then the refrigerator is cold so these conditions may have killed the bacteria. Also, the media we used may not have been the right choice for this object. Area Sampled Bottom of Shoe Incubated at 37 degrees Celsius 2 Days Diameter Whole-Colony Appearance Margin Elevation Pigment Number of this Type 1mm Circular Entire Raised Gray 8 1 cm Irregular Lobate Flat Gray 12 5 mm Biconvex Curled Flat Gray 2 Less than 1 mm Irregular Undulate Raised Gray 40+ Less than 1 mm Filamentous Filamentous Flat Gray 25+ Conclusions: If I were to redo this lab, there are several other environments I would like to sample. After completing discussion board 3 it got me thinking that it would be interesting to swab my hands and fingernails. I would love to have 3 plates one for my hands before cleaning, one for a sample after washing with antibacterial soap, and the third for sampling hands cleaned with hand sanitizer. I would be interested in doing this to see which option is more effective at killing bacteria on my hands. The criteria I used to determine whether colonies are from the same or different bacteria I examined things such as size, shape, color, amount, and the elevation of each different bacterium I saw on the plate. The difference between a colony and a colony forming unit is that a colony is a population of cells that arises from a single bacterial cell. A colony may arise from a group of the same microbes attached to one another, which is therefore called a colony forming unit or CFU. The environment that had the most total bacteria was the swab of the bottom of my shoe. The environment with the least amount of bacteria was my car key. I believe that the bottom of my shoe showed the most growth because I wear those shoes almost every single day. Also, the bottom of my shoe experiences different environments (cold, warm, room temp) so the bacteria did well with the incubation environment. As previously mentioned above, I believe that the bacteria on my car keys did not grow because the environment and media was not adequate for the survival of the microbes. I know that there definitely is bacteria on my car keys because I don’t typically wash or sanitize them however I just need to provide a different environment to see growth. The environment that had the most different bacteria would be the bottom of my shoe once again. The environment with the least amount of bacteria was the swab of my hair that I did. As I mentioned above, I wear those shoes every day so the bacteria on the bottom of them seems almost endless seeing that I tend to walk and go many places throughout the day. The swab of my hair however only grew one small circular raised bacteria. I believe this happened for several reasons. One could be that the environment such as the media and temperature of incubation was not adequate to produce growth. Secondly, I had just showered and washed my hair before class so there may not have been a lot of microbes to swab. Thirdly, I tried to only grab one small strand and maybe if I had grabbed a chunk and swabbed at a lot of hair maybe the results would have been more clear. Questions: One advantage of growing bacteria on Petri plates in this lab is that it is easier to view all the different types of bacteria that grew from the swabs because the plates are round, flat, and solid. If we grew our swabs on a slant it would have been much harder to study the growth and record the results. Disadvantages to using the Petri plates is that they are capped so anytime we take the top off we are exposing the media to outside bacteria other than what was swabbed. The bacteria are utilizing nutrients that come directly from the nutrient agar media that was used. The nutrient agar is made up of sodium chloride, beef extract, peptone, water, and agar. The bacteria survive because of these different ingredients that help promote bacterial growth. Agar is that it is an extract from marine red algae and possesses unique characteristics. Agar cannot really be degraded by microbes and therefore provides a solid surface for bacterial growth. Agar can also survive in in hot or cold environments which is important because in order to view the bacterial growth occurring the media must stay in tact. Critical Thinking: When pouring Nutrient agar into Petri plates, one must keep the cover slightly ajar while the agar cools. The plates do not become contaminated from organisms in the air because the agar is very hot and keeping the lid open slightly allows for heat to escape and trap outside microbes in the air from coming in. One could determine whether the turbidity in the nutrient broth tube was from a mixture of different microbes or from the growth of only one microbe by taking a loop of the bacteria and conducting a Streak Plate procedure to isolate the bacteria. Clinical Application: The effectiveness of sanitation procedures in hospitals is determined by sampling surfaces for bacteria. Samples are taken by rubbing a sterile cotton swab on a surface and inoculating a nutrient agar plate or with a Rodac environmental sampling plate. Therefore, with the results, when the samples are taken by swabbing onto a nutrient agar plate, the nutrient agar has a tendency to increase the growth of the microbe in a distinct manner by having 50 numbers of plates inoculated and producing 6 colonies. Contrary to this, when the sample are taken by swabbing onto a Rodac plate containing nutrient agar, the Rodac plate has less tendency than the nutrient agar plate to weigh the growth of the bacterium growing and only produced 40 numbers of plates inoculated and showing six colonies.