Bios242 lab 1 Essay

The following tests according to the lab manual were performed: gram stain, fermentation tubes, methyl red, vogues proskauer, sulfur, indole, motility and growing it up on MacConkey agar. The gram stain was performed incorrectly the first time. This is because the decolorizer was not on the bacterium slide for long enough, giving a false outcome.

Depending on what a bacteria can and cannot do, will help to correctly identify it. It is always important to start out with a purity check. To achieve that, you can inoculate an agar plate and incubate for 48 hours. Make sure you only see one type of colonies on the plate. Knowing the optimal temperature for the bacteria will also let a scientist know where to place the different types of medias he/she inoculates with the unknown bacteria. Knowing if you are working with a gram positive or gram negative bacterium, a scientist will need to perform a gram stain. This will also help to see the shape and arrangement of the bacteria. The size can be determined by doing a simple stain. The size of most bacteria ranges from .5- 10um. This specific bacteria that I was working with, was smaller than 2um. Most bacteria can grow with the presence of oxygen. A simple test like the gas pack can be performed to figure out if growth is possible without oxygen is doable. My unknown bacteria needs oxygen to grow. Throughout my study, the unknown bacteria was tested to see if it can grow in acidic conditions, however no growth occurred. Before inoculation, the substrate was a clear yellow color and in liquid state. After receiving the negative result, I kept the broth in the 37C incubator for 7 more days to confirm the negative result. Using premade slants with different types of sugars such as Mannitol, Sorbitol, Lactose, Trehalose, Maltose and Sucrose, to determine if the bacteria can metabolize glucose and if the bacteria is oxidative or fermentative. It was determined that my bacteria is strictly oxidative (needs oxygen to grow) and cannot metabolize glucose. Another test was done to confirm if the bacteria was able to utilize different carbohydrates in the presence of oxygen. I used Cellobiose, Arabinose, Adonitol, Fructose and Malonate wee tabs. Out of the 5 different types of carbohydrates, only 3 different

Lab Day 1: After receiving my unknown bacteria, I streaked a TSA plate and incubated at 37°C for 48 hours. I then picked a single colony from the plate with my sterile loop and streaked a TSA slant and labeled it “Working Stock”. I did the same with another TSA slant and label the second one “Back-up Stock”. This would be the samples I used to complete the following procedures through the next four weeks to determine my unknown bacteria.

For this experiment we will be testing four different bacteria with four different tests, using glucose, lactose, and sucrose. Hopefully we will use the information from those test to be able to identify the organisms in each of the samples from the case studies. We will use the results from the four different tests along with the information of how different bacteria react to match up to the case scenario and identify the bacteria, then check to see if our guess was correct. The findings are that we were able to identify, by process of elimination, the four different test bacteria.

Then well- isolated colon in mixed into the drop. If the mixture becomes viscous within 60 seconds of mixing the test is KOH- positive then the colony is considered gram-negative (Sutton, 2006). Gram positive bacteria don’t get slimy and, therefore do not string, so it will be negative for gram positive. The one advantage of the KOH test is the simplicity and it can be performed on older cultures. Nevertheless, if can result as false negative test if too little inoculum or too much KOH was used (Sutton, 2006). Therefore, different selective and differential media are used to in the identification of the unknown

The test tube was labeled with the bacteria identifying number. The cap on test tube was removed, and the lip of the test tube was flamed. Next, the Bunsen burner was used to sterilize the inoculating loop. Then, bacteria were picked up from the working plate with the loop and the agar was inoculated. The loop was then re-flamed. Finally, the plate was placed in the 37˚C incubator and left to sit for 48 hours and any changes in color were observed. A negative result appears green, and a positive result appears blue. This is because it tests for the organism’s ability to use citrate as its sole source of carbon, and if it does then it produces ammonia and ammonium hydroxide which make the medium basic, changing the green agar blue (Leboffe & Pierce,

There was also motility because there was growth away from the point of inoculation. It looked like an upside down Christmas tree in the tube. The last thing SIM tested for was indole production. It is produced when the bacteria converts amino acid tryptophan to indole. 5 drops of dimethylaminobenzaldehyde, or Kovacs reagent, was added to the test tube. Upon addition, if it is positive for indole, it will turn a red color at the top of the medium. When the unknown was tested, it did not produce a red color. There was a slight dark red/brown color, but overall the test result was negative.

The purpose of this paper is to identify an unknown bacterium by conducting five tests and removing possibilities from the list of unknown genera. After explaining what the tests are for, and why they’re conducted. I then interpreted, analyzed, and explained the outcomes of each test. I was then given a 16S rRNA sequence that I’m able to input into the Basic Local Alignment Search Tool and find out what genus my bacterium is. Finally, comparing whether my results correlate with the bacterium shown after the Basic Local Alignment Search Tool.

The objective of the unknown experiment is to identify two different possible bacteria samples. Test tube #116 was randomly selected and was identified as containing Micrococcus luteus and Proteus Vulgaris. To come to this conclusion, test tube #116 was subjected

For the Gram stain, I used a microscope slide, wash bottle of water, clothespin, and the reagents crystal violet, Gram’s iodine, ethyl alcohol, and safranin to observe whether the organism was Gram negative or positve. The method was placing and heat fixing a loopful of the unknown organism on the slide. The organisms were then stained with crystal violet for a minute, rinsed off, flooded with iodine for a minute, rinsed off, decolorized with alcohol for 30 seconds, and then finally stained with the counter-stain, safranin, for a minute. I streaked the unknown onto a TSA plate and incubated at 35 C. With a pure colony, we performed a second gram stain procedure and inoculated it into a TSA slant. I used BCP Lactose broth and a loop to perform a BCP Lactose test. The broth was inoculated with a loopful of the unknown and incubated

(ii). Always wear closed to shoes when working with beaker/glass, to protect from glass in your feet.

Dispose and clean up the contents of your test tubes and put away all of your materials. Clean up your work station and hands.

First, I divided the key into gram positive and gram negative bacteria. Then I divided the positive half of my key by morphology, rods and cocci. The other negative half was divided by morphology as well, into rods and cocci, but since we were not using any Gram negative cocci, that path was a dead end. Gram positive rods consisted of Bacillus subtitles, and Corynebacterium. Gram positive cocci consisted of Micrococcus luteus, Staphylococcus aureus, and Streptococcus faecalis.

7. With the information provided in this lab, what steps would you take to prevent a reoccurrence of an

A urease test was next on the agenda. A urease slant is used to indicate whether a bacteria is able to produce urease, that breaks down urea into ammonia and carbon dioxide. This causes the slant to become more alkaline and is indicated by the phenol red within the slant by changing to a hot pink color. Using a sterilized inoculation loop I obtained a sample of Unknown 1B and carefully streaked the surface of the urea slant. I replaced the cap onto the urea slant but did not tighten, this test requires aerobic conditions. I then wrapped the tube in foil prior to