Methyl Red Voges-Proskauer Test Lab

This experiment was centered on metabolic and biochemical testing procedures. The rationale of performing these tests was to distinguish six different microbes from one another and to compare how their metabolic and biochemical processes differ from species to species to determine the unknown sample.

“Ajax Spray ‘n’ Wipe” specifically states that it kills E. coli. This is because of the lactic acid in the spray, which is used as a natural antibacterial agent.” ("Colgate-Palmolive | Product Ingredients"). Lactic acid kills unwanted bacteria especially in food which is where E. coli is often found and transmitted, of which meat is the most common cause. Vinegar was chosen as a substance because “it can be used as a bleach alternative” (“Disinfectants: A Guide to Killing Germs the Right Way”) and bleach kills E. coli. It is also used as an everyday cleaning product. The last substance chosen was salty water because it is thought that salt kills bacteria. Much of the world’s population has access to salt and if the experiment proves that salt kills E. coli it would be a helpful factor for further treatment of the

The purpose of this lab was to identify unknown bacteria cultures using various differential tests, and my unknown bacteria is #17. The identification of these unknown cultures was accomplished by separating and differentiating possible bacteria based on specific biochemical characteristics. Whether the tests performed identified specific enzymatic reactions or metabolic pathways, each was used in a way to help recognize those specifics and identify the unknown cultures. The differential tests used to identify the unknown cultures were Gram stain, Catalase, Mannitol Salt Agar (MSA), Blood Agar, Novobiocin, Coagulase, and DNAse (Alachi, 2007).

Negative result is no color change with mineral oil on top of solution. This bacterium has +/- reaction on MAC plate. It could survive in an acidic environment, but it not able to ferment lactose. The bacteria grow on the plate, but did not change the color of the plate to bright pink. This bacterium has a +/- result on Bile Esculin Agar.

To perform this test, a tube of broth rich with glucose is acquired. In this tube is phenol red, a pH indicator. Initially, the tube appeared pink in color, indicating a normal pH level. Next, a sample of unknown #44 is introduced into this medium using the aseptic technique, and this is allowed to sit for several days. If the organism is able to ferment glucose, the pH in the medium would decrease and cause the phenol red to exhibit a yellow color. In addition to the straw color, gas can also be produced and trapped inside the Durham tube placed in the medium. This production of acid and gas is a direct result of the fermentation of glucose, as seen with unknown

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

When investigating this experiment I found many different types of antiseptics all with different effects on bacteria and the effectiveness of all these antiseptics varied. I found

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.

In the world of microbiology it is vitally important to be able to discern the identities of microorganisms. Not only is it important in a lab setting but as well as in healthcare in general. Properly identify what strain of bacteria a person has will aid in the proper medicine and dose given. Throughout the semester we have learned about different types of bacteria and certain test that can clearly identify them. The purpose of this lab report is to identify a Gram-positive or Gram-negative bacterium. Using all the knowledge of procedures and lab techniques identify the unknown and discuss all the tests you performed.

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

On August 19th, 2015 this experiment was performed, by 6 separate lab groups.The experiment began by measuring 1 Ml of E. coli into a pipette and pump, then placing the bacteria into a culture medium. The E. coli and medium were then swirled together for a period of 15 minutes, until completely mixed. This mixture was then poured into a petri dish and allowed to solidify for 45 minutes. After the 45 minute solidification time, 5 small paper disks were inserted into the dish. 4 of the disk contained treatments of antibiotic and 1 was left untreated. The

I believe the bacteria in tube 30A is E. faecalis, and the bacteria in tube 29B is E. coli. For tube A, the DNase test yielded a negative result, with absolutely no clearing on the agar. Only three bacteria would produce a negative result: S. epidermidis, E. faecalis, and M. luteus. From there, I performed a catalase test, in hopes of attaining a negative result. The result of the catalase test was, in fact, negative. This eliminated both S. epidermidis and M. luteus because these bacteria would have yielded a positive result. The result of the catalase test was completely negative, as evidence by no bubbles being produced after the addition of a drop of hydrogen peroxide. For tube B, the first test I performed was a EMB plate test. The result

Name ____________________________ I) Introduction All cells contain four major types of macromolecules: carbohydrates, lipids, nucleic acids, and proteins. In today’s lab, we will be studying three of the four-proteins, carbohydrates and lipids. Various chemical tests can be used to detect the presence of each of these molecules. Most of the tests involve a color change visible to the eye. If a color change is observed, the test is considered positive. If the color change is not observed, the test is negative, indicating that a particular molecule is not present. In all the chemical tests we will be performing, we will also be using a control. In most cases, the control will be a sample of

This experiment was performed to test the hypothesis if LB nutrient broth, +pGLO and -pGLO Ampicillin, and Arabinose was placed in the E. coli plates, then there will be a significant growth in the newly transformed bacteria and it will possess the ability to glow under UV light. The measurements were recorded from the bent glass tube in each glass test tube. The transformation protocol tested for the newly possessed traits in E.coli bacteria. Throughout the experiment there were many probable reasons for failure. If the pipettes and sterile loop were not thrown out in between each use, a cross contamination could cause a miscalculation in the experiment causing the data results to fail. The hypothesis that was tested was validated due to the positive results with each experiment stating that newly transformed organisms due in fact pass on traits.

Broth cultures of E.coli, Micrococcus luteus and Vibrio natriegens were streaked onto the respective sections. The plate was then incubated at 37oC for 48 hours. The process was then repeated on nutrient agar plates with 5, 6.5 and 10% salt.