Serial Dilutions: Salmonella Typhimurium Culture

The overall goal is to either discover a new novel phage that has not yet been discovered, or provide new research on an already discovered phage. The isolation of the phage takes several steps under the streak protocol that is present in materials and methods section of this report.

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.

This experiment is about bacterial growth. We will demonstrate a bacterial growth curve using a closed system. Bacterial growth usually takes up to 12-24 hours to get an accurate result so we will be monitoring this growth between two classes. We also used different methods to determine bacterial growth as well as a few different calculations. One way of receiving data is by using a spectrophotometer where we will record the absorption at a given time to create the bacterial growth curve. We also used the plate count method after performing a serial dilution to calculate the actual cell density at different times given. By using this method we can count the population number of the same given and see the maximum cell density

5 drops of chloroform were added to the mixture and incubated at room temperature for 15 minutes to kill, and lyse the bacteria cells which allows all the unadsorbed phages to be accounted for when determining the titer of unadsorbed phage with susceptible bacteria, E. Coli B. (Biology Dept.). 0.1 ml of E.coli B was added to the 10 fold dilution. Using soft agar technique, the unadsorbed phage were plated. After incubation, the titer of unadsorbed phage was determined by counting the number of plaques on the plate from the infection of single E. coli cells in the assay tube by a free phage particle before

For the temperature test each bacteria was placed on a nutrient agar and incubated for either 10, 20, 30, 40, or 50 degrees Celsius for 48 hours. During the pH test, each organism was placed on four agars varying in pH level from pH 2, 4, 6 and 8 and incubated near 37 degrees Celsius for 48 hours. For the osmotic pressure test, each organism was placed on four agars one each containing 2%, 5%, 8%, and 11% NaCl concentration levels. These were incubated near 37 degrees Celsius for 48 hours. The results of the tests are recorded in Tables 1, 2, and 3. All tests were performed according to the instructions provided in Leboffe & Pierce(1). The biochemical tests used on both unknowns and the ubiquity are:

This lab experiment was done for the purpose of learning how to determine a gram negative bacterium based on multiple tests learned throughout the semester. My gram negative unknown bacterium given to me was Salmonella typhimurium based off of the following tests; Triple Sugar Iron Agar (TSIA), Sulfate Indole Motility (SIM), Methyl Red (MR), Voges-Proskaur (VP), Citrate, Urea Hydrolysis, and Gelatin Hydrolysis. Each test performed gives results such as motility, acid production, fermentation, carbon requirements, or detection of certain coenzymes. With a process of elimination, I determined which bacteria it was not and which bacterium I had, S. typhimurium. The expectation was to master the techniques for each test and utilize the results to determine the unknown bacterium I was given within a two-week period.

70µL of competent E.coli are added to both test tubes; pUC18 and Lux (Alberte et al., 2012). Both test tubes are then tapped and placed back into the ice bath for 15 minutes. While waiting, another test tube is obtained, filled with 35µL of competent cells and labeled NP for no plasmid. A water bath is preheated to 37 degrees Celsius and all three labeled test tubes are inserted into the bath for five minutes (Alberte et al., 2012). Using a sterile pipet 300µL of nutrient broth are inserted into both the control and Lux test tubes and 150µL are inserted to the no plasmid test tube to increase bacterial growth. All three test tubes are then incubated at 37 degrees for 45 minutes. Six agar plates are obtained and labeled to correspond each test tube, three of the plates contain ampicillin. A pipet is used to remove 130µl from each test tube containing a plasmid and insert it into the corresponding agar plate. For this, a cell spreader is first

# of plaques/(volume plated x reciprocal of the dilution factor of the dilution tube used)

There were two tubes used in this process: the tube that contained the primary culture and the tube that contained the nutrient agar where the unknown bacteria would grow. First, the inoculating loop was flamed. After removing the caps of both the test tubes, they were flamed to prevent contamination of the unknown bacteria. The inoculating loop was cooled for a few seconds and was then placed into the test tube containing the bacteria. The inoculating loop with the bacteria was placed into the nutrient agar test tube for cultivation. Before the test tubes were capped, they were flamed once again. Also, isolation of the unknown bacteria had to completed. Nutrient agar was placed in the petri dish, and was left to gel for a few minutes. After the agar gelled, the inoculating loop was used to acquire bacteria and streak the unknown onto the plate for

This project is all about isolating bacteriophage in soil. They come in different sizes and shapes, each to their own unique look. Phages have a protective protein head that contains DNA and a hollow tube tails (http://phages.org/bacteriophage/). Since bacteriophage cannot reproduce and replicate themselves, they need a host to do the work for

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,

4) A MSA plate test was run on a sample of the organism and the results were consistent with the given results for M. Luteus. The results showed a fair amount of growth on the plate, and the color of the agar around the growth remained red. The MSA test is selective in that the salt will inhibit most gram negative organisms and select for gram positives. If there is growth and the color of the agar turns yellow around the growth, this would mean that mannitol was fermented by the organism and the acid waste released by the bacterium lowered the pH around the growth. Since there was growth and no color change, the sample is said to be gram positive and unable to ferment mannitol (negative for differential). This result was also consistent with the given test results for M. Luteus.

Next the tubes were placed in an ice bath, while obtaining a sterile loop to swipe a single colony of E.coli to put into the tube. After gently swiping a colony onto the loop, it was then spun in the +pGLO tube to get it to come off, returned to the ice bath. Next using a different sterile loop, it was swooped it in a container labeled pGLO plasmid DNA and again spun it ONLY into the tube with the solution labeled +pGLO to get it to come off. After about 10 minutes on ice the tubes were then placed into a 42ºC water bath for 50 seconds exactly, and immediately after placed them back into the ice bath. Finally, after 2 more minutes in the ice bath the tubes were separated into 4 containers. 250 ul of +pGLO solution was added to the containers containing +pGLO, LB broth, with ampicillin and +pGLO, LB broth, ampicillin, with arabinose. Also 250 ul of the –pGLO solution was added to the 2 containers containing LB broth, and ampicillin, with LB broth. Using a sterile loop for each plate the solutions were spread out gently and thoroughly on to the containers with agar. After the containers were incubated in 37ºC for at least 24 hours, the results were observed and disposed of (Weedman,

On day 3, I was able to perform the P disc sensitivity test. I asked for the correct media and I was able to inoculate on CNA using aseptic technique. I performed a lawn technique getting bacteria from the T-soy plate inoculated the first day. I used a swab dipped in sterile water and smeared the whole plate forming a lawn. To get the P disc from the container a used forceps to place the disc in the middle of the plate. The plate was place inverted in a candle jar for incubation. I disposed of the used materials using the proper disposal

A sterile pipette was used to add 0.1ml of E. coli culture to the pH 3.0 tube. This was then repeated for the tubes at pH 7.0 and pH 9.The tubes were then incubated at 37oC for 48 hours. This was then repeated for saline culture of Saccharomyces cerevisiae but incubated for 72 hours at 25oC.