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.
After selecting the unknown sample # 2, the gram stain technique was performed in order to correctly identify the microbes. Gram staining is considered a differential media because staining differentiates between gram negative and gram positive bacteria. The purpose of the gram stain is to give crucial information as to whether the bacteria has a positive or negative cell wall, provides rapid results to physicians, and identifies the shape and arrangement of the organisms. The gram stain of sample # 2 reveals that one of the unknown microbes is a gram negative bacillus/rod and the other is a gram negative coccus. The EMB plate was used to isolate the gram negative rod because the EMB plate is selective for gram negative rods, inhibiting the growth of gram positive organisms.
To test an organism’s ability to use citrate as a source of carbon, a citrate utilization test is. This test is ... ... middle of paper ... ...n dioxide. The ammonia would cause the broth’s pH to be alkaline, which would turn the broth bright pink (3). Since the broth stayed the same orange/yellow color, we know that the urea in the broth was not degraded to ammonia, meaning that the organism does not produce the enzyme urease. Literature Cited 1) Bartholomew, J.W., and T. Mittwer.
Sucrose and lactose serve as fermentable carbohydrate sources which encourage growth and allow one to differentiate between fermenting and non-fermenting microbes. Vigorous fermenters of lactose or sucrose will produce quantities of acid sufficient to form the dark purple dye complex which is usually associated with a green metallic sheen. Slow fermenters will produce a smaller amount of acid production and appear brown-pink in color (Lab Handout; EMB). This experiment resulted in no color change which was expected as two previous tests indicated that my unknown was a gram- positive bacteria and this test is selective for gram-negative bacteria.
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.
This is why gram positive bacteria have high metal adsorptive capacity and gram negative bacteria have poor metal adsorptive capacity (Gavrilescu 2004). The m... ... middle of paper ... ...e enzymatic reduction of radionuclides can also be stimulated or induced indirectly by the reduction of some other soluble elements present in close vicinity of radionuclides. The reduced forms of these other species further promote the reduction of radionuclides. 4.2.3 Biosorption of Radionuclides Biosorption can be defined as the sequestration of positively charged radionuclides to the cell membrane molecules of the bacteria which are negatively charged. These negatively charged molecules include polysaccharides, teichoic acid etc.
This test usually used to differentiate catalase positive bacteria such as Staphylococcus spp. and the Micrococcus spp. from catalase negative Streptococcus and Enterococcus spp. Bacteria lacking the cytochrome system, also lack the catalase enzyme and are unable to break down hydrogen peroxide, into oxygen and water and are catalase negative. The effervescence resulting from production of oxygen gas clearly indicate a catalase positive result.
There was no change in color of the broth which indicated a negative result. Unknown 3 was also inoculated in a Urease broth, which tested for the presence of Urease, an enzyme responsible for hydrolyzing Urea into ammonia and carbon dioxide. If Urea had metabolized, indicating a positive test, the broth would have turned pink. The test was negative. The figures below provide a summary and supplement the analysis; Figure 1 describes the purpose of the test, the results and its implicatio... ... middle of paper ... ...s culminates in the identification of the organism Micrococcus roseus.
Based on the fermentation testes the microbe did ferment Glucose, Sucrose, lactose and Maltose. Si... ... middle of paper ... ...ll biochemical tests performed came out as expected except for the starch and urea digestion. On the first test starch shows a false + test and then on the second test it comes as a negative result. The same thing happened with the urea digestion it showed a false + test on the second test as a negative result, matching the result of a known bacterium, staphylococcus aureus.Therefore, it was concluded that unknown #79 was staphylococcus aureus. References Community college of Denver (2014).Introduction to microbiology laboratory manual.Boston,MA;person Learning solution Oxidative/fermentation glucose test.
Introduction Bacteria are grouped into two categories as Gram positive and Gram negative. The bacteria that retain the color of the primary stain are gram positive and the bacteria that lose the color of primary stain are called gram negative bacteria. Gram positive cells have a thicker peptidoglycan layer and doesn 't contain the outer membrane. Gram positive cells will retain the primary stain of crystal violet because they have a thick outer layer of peptidoglycan that traps the dye among its high degree of teichoic acid crosslinks. On the other hand, Gram (-) cells have a thin peptidoglycan layer and an outer membrane, gram negatives have an outer membrane made up of Lipopolysaccharide, proteins and prions and have thin peptidoglycan layer with higher lipid content that are targeted by the alcohol/ acetone decolorizer and makes the cell’s outer layers more porous, thus they are unable to retain the primary stain.