Microbiology- Identifying Unknowns: Micro. Lueteus

An unknown bacterium was handed out by Dr. Honer. The appropriate tests were prepared and applied. The first procedure that was done was the gram stain. Under a microscope, if the gram stain is purple, the bacterium is gram positive, if the stain is red, it is gram negative. The next test was the fermentation tests for glucose, sucrose and

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

The first test executed was the fermentation of carbohydrates. The objective of this particular test is to identify the ability of microorganisms to ferment a specific carbohydrate (Reiner, 2012). The test can be used to identify three different ways in which bacteria can ferment simple carbohydrates. Bacteria can be tested for acidity, alkalinity, whether or not it remains neutral and gas formation (Reiner, 2012). To conduct the carbohydrate fermentation test, a pH indicator, bromocresol purple, is used to indicate an acidic characteristic (Reiner, 2012). Bromocrescol purple indicates carbohydrate fermentation media by turning a deep purple if it’s an uninoculated media, yellow if it’s acidic and purple if it’s alkaline (Reiner, 2012). Durham tubes are placed inside the tubes containing the media and bacteria to detect gas production (Reiner, 2012). Three different carbohydrates were tested for fermentation during this test: glucose, sucrose and lactose for each of the

The purpose of this lab was to identify an unknown bacteria culture using differential tests. The identification of the unknown culture was accomplished by identifying the bacteria based on its specific metabolic characteristics and morphology. It is suggested that culture 11 is a sample of Enterobacter aerogenes.

I achieved an isolated Gram negative bacteria because I modified the four-quadrant streak style and time. I believe that my Gram negative bacteria were a fast grower and would over grow the Gram positive. On the 4th day I was able to successfully isolate my Gram negative, and proceeded to run the SIM test and the TSI test as instructed. Both tests produced black precipitants, indicating sulfur reduction. This narrowed down my possible Gram negative bacteria to four bacteria. As I continued to analyze the SIM test the results showed motility, which was confirmed by my TA and indole production. With this test I was able to narrow it down to 2 bacteria. I think did another Gram stain to confirm no contamination, once confirmed, I decided to do

For this experiment, we were given three gram staining slides as well as a petri dish with five different types of incubated microorganisms that were divided. The five different organisms on the petri dish being observed were Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Klebsiella pneumonia, and yeast known as Candida albicans. On the surface of the

The first test I conducted was on the MAC agar because it could show the ability of the microorganism to ferment lactose. The neutral red indicator serves to contrast the lactose-fermenting from the non lactose-fermenting organisms. My bacteria remained translucent and the medium kept it color which means that the organism did not ferment lactose.

I saw bacteria growth on both two LB tube which was incubated at 250C and other at 370C. I used one tube for the further test, and the other was incubated at 40C to keep bacteria fresh and growth for other test. On the PEA plate, unknown bacteria did not growth, and on the EMB plate, bacteria had growth very strong. The result confirms one more time the unknown bacteria was gram negative because the PEA plate inhibited DNA synthesis of gram negative so bacteria could not grow on the PEA plate. On the other hand, EMB plate inhibited growth of gram positive so my unknown bacteria grew in this. After I recorded all my result, I continued to set up several test for the next day. Next, I set up PR fermentation test which include 3 broths glucose, sucrose, and lactose. I also set up PAD and Urea

The purpose of the gram stain test is to see if an organism is gram negative or gram positive based on it’s color and shape. Using an inoculating loop and inserting it into the incinerator for 10 seconds, it was sterilized. A small drop of water was then applied onto a clean glass slide by using the now sterile inoculating loop. The loop was used to spread the organism back and forth on the slide until a good portion of the glass is covered. The organism and water were left to dry completely before heat fixing the glass slide. After heat fixing, over a sink crystal violet was applied to the glass slide for one minute. It was then rinsed with water and iodine was applied for one minute. The slide was then rinsed with water and 95% ethanol was

According to page 24 of the lab manual, Gram-positive bacteria are able to grow on a PEA medium but not EMB-lactose (Holbrook & Leicht, 2013). Therefore, further testing had to be done that would identify the gram-positive or gram-negative state in the Catalase and Oxidase test. The result of the KOH Test, also Table 1, as gram-positive, because the bacterium we tested did not form a string. Because of the mixture of identities the Catalase test and Oxidase test were used (Figure 2). These both resulted in a very strong gram-positive reaction. During the Catalase test, after placing a drop of H2O2 on our slide, an immediate strong reaction of bubbles formed. This confirms our specimen as catalase-positive bacteria. The Oxidase test showed strong reaction in the gram-positive designated areas confirming, with the Catalase test, that the bacteria most likely is gram-positive. This concludes the observational-based testing

In this experiment individuals were given a plate with two unknown specimens. Each group completed a gram stain followed by a series of other test in order to identify the unknown bacteria. Each student conducted separate testing’s on one unknown in order to specifically identify the strain.

(4 marks) What is the use of negative staining? (2 marks) c) Most genera of bacteria will lose the red carbolfuchsin stain when decolourized using acid alcohol but those that are "acid-fast" retain the bright red colour in ZiehlNielsen Acid-Fast stain. What could be the explanation for this colour differences. (3 marks) You are given a bacterial sample and your task is to find out whether the bacteria are motile or not. Suggest three (3) lab procedures that enable you to test on the bacterial sample. (3 marks)

Before I performed any experiments, however, I made educated guesses/hypotheses regarding the identities of each unknown microorganism. Firstly, my assigned sample, B2 and the other bacterial sample F7 were transparent before the gram test so I could not make a hypothesis about them without any information to base it off of. However, I assumed that A4 is a type of algae due to the small flagella (used for water navigation) and green color it possessed and that F10 is a eukaryote of some sort due to its cells ' constant movement. Before performing the complete identification tests on the B2 sample, I could not make guesses regarding their results because I lacked information about the basic properties of the bacteria that gram-staining and ocular

Another purpose of this experiment is to stress the importance of knowing the identity of a microorganism. Knowing the species of microorganism present in a sample provides a

There are many different physiological tests one can used to identify bacteria. For this project, one can use a spore stain to see if a bacteria can produce spores in response to nutrient depletion.(Intrieri, 2014) There is also the catalase tests, which show whether bacteria possesses the enzyme catalase, which can handle reactive oxygen species (Intrieri, 2014). There is also the oxidase test, which tests for the presence of oxidase in a bacteria, which indicates the bacteria contains cytochrome c (Intrieri, 2014). Another useful test to differentiate bacteria is the Entero-Plueri Test®, which performs multiple tests in one setting, like