A gram stain is a differential type of stain that determines whether a cell is gram-positive or gram-negative. "Bacterial size, morphology and arrangement can also be determined using this stain" (2). The negative charge on bacterial cells attract the positive charge on the stains used, thus causes the cell to be colorized (2). The gram stain conducted on unknown #53 did not retain the crystal violet when decolorized. The unknown bacteria adhered better to the Safranin stain and was shown to be a pink stained bacterium under the microscope.
So I started up with an alkaline solution that was not metabolically changed by the bacteria into an acid solution. Gas can also be produced as a positive result. Another test that was done was the triple sugar iron test. A loop full of the bacteria was transferred from the TSA plate to the broth; a spiral streak was carefully done to prevent poking the broth. A positive result changes to a dark color and a negative test did not.
Introduction The objective of this lab was to identify unknown bacteria culture by using various differential tests. There are many reasons for knowing the identity of microorganisms including to find the correct antibiotic to treat infections the bacteria may have caused. All the methods and techniques used to identify unknown bacterium #79 was learned in the microbiology laboratory. Test Result Unknown# 79 was grown on TSA slant in a 370 c temperature after two days, the microbe replicated to more than 100 microorganisms, which has cream pigments, and convex elevations. The microbe entire margins and convex elevations.
On the other hand, E.coli and P. vulgaris formed colonies on the plate. This indicates that MAC agar consists of selective properties. The colony of E.coli was pink colour because it was a lactose fermenter while P.vulgaris was non-lactose fermenting bacteria formed beige colour. Q3 and Q4The lactose present in the agar is a fermentable sugar in which provide a ca... ... middle of paper ... ...h the bacteria on the agar plate. If the plates are incubated for more than 24 hours, some of the organisms which ferment lactose late (enterbacteria) will tend to appear pink colonies on the agar plate.
The purple colonies on the EMB plate reveal that the gram negative bacteria is able to ferment lactose and sucrose. A gram stain of the colonies from the EMB plate show only the gram negative rods thus making the colonies on the plates pure. A BAP plate was chosen to isolate the gram positive coccus. The BAP plate was chosen instead of the MSA plate because Citrobracter freundii can grow and break down mannitol. If Citrobracter freundii, a gram negative rod, and Staphylococcus aureus, a gram positive coccus, were the two unknown bacteria in the sample, then it would be difficult to know which bacteria caused... ... middle of paper ... ...atient is immunocompromised from the chemotherapy for lymphoblastic leukemia; the longer she stayed at the hospital for treatment, the more susceptible she was to contract the UTI from Enterobacter aerogenes.
The bacteria ferment lactose, then cause the pH of the media agar to drop and resultant change in pH is detected by neutral red. The neutral red is absorbed by the lactose fermenting bacteria and appear as bright pink to red on the MacConkey agar. The strong lactose fermenting bacteria produce resulting in a pink halo in medium while the weaker growing on MacConkey agar will still appear pink to red but will not be surrounded by a pink halo in the surrounding medium. The gram-negative bacteria that grow but do not ferment lactose appear as colourless on MacConkey agar plate. The agar surrounding the bacteria remains transparent.
Several lab experiments were performed to determine the species of an unknown culture. During staining the bacteria was determined to be gram negative after a differential gram stain was performed. The bacteria stained purple. When visualizing the bacteria, the bacteria were rod shaped and largely individuals instead of in groups. It was determined using Thioglycollate agar deep the unknown culture was inoculated using a stabbing technique, and it was determined that the bacteria is facultative.
The first chemical to stain the slide is crystal violet which contains a purple color stain and indicates a gram positive bacteria. Add enough crystal violet stain to the slide and let it sit for sixty seconds. Then, rinse the substance under slow running water. The second chemical to stain is gram iodine which fixes the dye to the cell walls of bacteria and makes the stain permanent. Add the same amount as preview of the gram iodine stain to the slide.
These tests were the EMB test (Eosin Mehylene Blue), the Sulfur Indole Motility (SIM) test, the Urease test, and the Simmon’s Citrate Utilization test. The EMB test checks for a bacteria’s ability to ferment lactose. This test is accomplished by placing the bacteria on Eosin Methylene Blue agar. The agar is selective for gram negative bacteria and those bacteria that can ferment lactose will have colored growth, usually a metallic green sheen. The Sulfur Indole Motility agar tests for three separate characteristics; sulfur reduction, indole production, and motility.
Which Functional Groups Were Present in Certain Substances This lab used many test to determine which functional groups were present in certain substance. The Benedicts test was used to identify reducing sugars (glucose and fructose) based on their ability to reuce the Capric ions to cuprous oxide at high pH. The Cuprous oxide is reddish orange in color when shown to be at high levels by the test, and greenish when at low levels. In both the onion juice and glucose solution the reducing sugar levels were very high, because the test came back dark orange. The starch solution had relatively low levels of reducing sugar present and this was seen by the test coming back cloundy blue, green and brown.