Qualitative Test Lab 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.

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:

The purpose of this lab was to identify two unknown bacteria cultures using various differential tests. 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 oxidase, catalase, lactose and sucrose fermentation, Kugler/iron agar, nitrate reduction, gelatin hydrolysis, starch hydrolysis, manitol salt, MR-VP, citrate, bile esculin,

The purpose of this experiment is to distinguish and indentify an unknown bacterium. There are several tests that can help one eliminate and narrow down the options. The most useful test, and the very first one done, is a gram stain. This test will tell whether the bacterium is gram-positive or gram-negative. After the type of gram stain is identified, the tester has a wide array of differentiating tests at their disposal. Based on the results from these tests, and the numerous others that are available, one can accurately establish the identity of an unknown bacterium.

In conclusion, after conducting previously mentioned biochemical tests in order to identify the unknown bacteria, became obvious that unknown gram negative was Proteus Vulgaris. Having eliminated all the bacteria that didn’t show expected results and confirming with such tests as catalase, glucose, indole, citrate, urea, and SIM, it was accurate to name the unknown gram negative. Furthermore, gram positive became obvious it was Streptococcus Pneumoniae. Having eliminated all the bacteria that didn’t show expected results and confirming with such tests as blood agar, catalase, and optochin and bacitracin tests, it was accurate to name the unknown gram positive. I have learned that it is extremely important to be to able to identify what kind

Bacteria, single-cell microorganisms, are found all over the planet. Some can be beneficial to their enviroment, while others can be pathogenic. Enterococcus faecalis is a resilient bacterium that resides in the intestinal tract of humans and mammals. Due to their ability to colonize at a rapid rate, E. faecalis cause a multitude of infections. To determine an unknown bacteria, one gram stain and two biochemical tests, a catalase and RBC hemolysis test, were performed. The gram stain showed gram-positive cocci bacteria, which lead to the catalase test. The test for

The best and most accurate way of identifying an unknown microorganism is by sequencing its DNA, but this is very expensive and only used in highly qualified labs. So, the identification of unknown bacteria number 63 was be done by putting the bacteria through numerous laboratory tests. Microorganisms are different among each other by their macroscopic morphology, microscopic morphology, and the unique metabolic processes they use to survive and reproduce. Identifying an unknown microorganism in the laboratory is important because knowledge is gained on the appropriate way to cultivate an organism, how to correctly read the result of a test, and learning about the different characteristics of the bacteria. All of the following tests were done using the best sterile technique and the most new turbid bacterial growth subculture.

The purpose of this activity is to determine the identity of four household substances, and to understand how to create and use a qualitative analysis scheme. This activity utilizes qualitative observation.

The fourth test used to identify gram negative bacteria is the Simmon’s Citrate Utilization test. This test measures a bacteria’s ability to use citrate as its sole carbon source for metabolic pathways. This solid medium contains Bromothymol Blue, which serves as a pH indicator. If the bacteria can break down citrate it produces carbon dioxide that reacts with sodium and water, also found in the medium, to produce sodium carbonate. Sodium carbonate elevates the pH causing a color change from green to blue (a positive result).

It is important for one to understand how microorganisms function as well as their identity. Identifying unknown microorganisms are beneficial to both scientist and patients. Reason being is due to bacterium capable of becoming resistant to antibiotics over a period of time. In order for doctors to treat patients to the best of their ability it is vital that they are able to identify the bacteria first in order to provide proper treatment. In order to identify the two unknown bacterium proper procedures were done. This study was done by applying all of the necessary methods that have been learned thus far in the microbiology laboratory.

The purpose of the Gram Stain test was to identify the morphology and gram nature of the unknown bacteria (Delfiner, Martinez, & Pavia, 2016). First, a mixed smear from the unknown bacterium was placed on a microscope slide. Once the mixed smear had air dried it was then heat fixed to adhere the bacterial cells to the slide. After the heat fixation, a series of stains/solutions were added to complete the Gram stain test. The series of stains/solutions included Crystal violet (1min), Iodine (1min), ethanol (2-3 drops), and Safranin (30 sec). Also, after the addition of the Crystal violet and Safranin, DI water was used to remove the stains. Lastly, bibulous paper was used to blot dry the microscope slide and the slide was placed under the microscope. To clearly identify the morphology and gram nature of the unknown, a drop of oil immersion was placed on the slide to utilize the oil immersion

This report contains the background information on gram positive and gram negative bacteria, which will aid in understanding the use of specific laboratory experiments to distinguish between the two types of bacteria. Included are the materials and methods used to identify the gram positive and gram negative bacteria and methods which also differentiate between microbes of each group. The implications of the methods of identification used are also described in this report to give an explanation as to why a certain route was taken in carrying out experiment 14. The results of the experiment carried out for the identification of three unknowns are tabulated

Different strains of E.coli can be isolated and identified by a variety of biochemical tests. The biochemical tests commonly used to identify E.coli include: lactose, oxidase, indole, and beta-glucuronidase tests. The use of lactose to identify a strain of E.coli is an appropriate method since intestinal bacteria, such as E.coli, typically undergo lactose fermentation. Using MacConkey agar, microbiologist are able to analyze if lactose is fermented and detected by the change of color in the medium. The oxidase test is used to identify if the bacteria synthesizes the enzyme cytochrome c oxidase that is part of the electron transport chain. When the enzyme cytochrome c oxidase is present, the reduced reagent, tetramethyl-p-phenylenediamine will donate its electron to cytochrome c oxidase and a purple color end product will show in the media. The indole test is performed by microbiologist to determine if E.coli is capable of converting tryptophan to indole. Lastly, beta-glucuronidase test is used to determine if an organism produces the enzyme glucuronidase by hydrolysis of nitrophenyl-beta-glucopyranosiduronic acid. In the presence of glucuronidase, the medium develops a yellow color (Trepeta & Edberg,

spectroscopy. Semen analysis was performed according to the Sigma-Aldrich Company guidelines. Нestrong and positive correlation was

Before starting all the biochemical tests, an inoculation procedure must happen. An unknown test tube was handed out which contained two different cultures. The unknown culture was place on a nutrient agar plate using the three-streak inoculation technique for isolation (Lab Manual, Chess 2015). After a few days of growing, the presence of two unknown bacteria had a clear visible of separation. Following the isolation streak technique, the gram-staining experiment was performed. The two bacteria were determined: one was Gram-negative bacteria and the other was Gram-positive bacteria.