The first test conducted on unknown bacteria 32 was the Gram stain. From this stain, unknown 32 was found to be a Gram-positive cocci. This test eliminated all possible Gram-negative bacteria, Gram-positive rods and Gram-positive spirillium. Next, the endospore test determined whether or not the Gram-positive bacteria contained endospores. With the use of malachite green, steam, and safranin it was found that unknown bacteria 32 did not contain endospores.…
In this lab, we isolated and compared bacteria from our skin and throat. We created two nutrient agar plates, three mannitol agar plates and two blood agar plates (seven in total). These plates were streaked with bacteria from either the skin or the throat. The skin streaks were done before and after washing the face and then incubated at 37 degrees for 48 hours. The throat streaks were also incubated at 37 degrees for 48 hours. On both the Mannitol Salt Agar plate and Nutrient Agar plate the number of bacterial colonies was too numerous to count before washing, as seen in the results. After washing the Mannitol Salt Agar plate had about ten bacterial colonies and the Nutrient agar plate had zero, as seen in the results. In the second lab, we observed the colonies after incubation and chose a new colony for restreak and incubation. After performing gram stains, we were unable to determine for the throat swab due to an error in the overuse of crystallized violent. In the third lab we examined the Mannitol Salt agar and Blood Agar restreak plates and found that the colonies were the same as the originals. For the throat and face restreak after performing the gram stain we were able to determine that the isolated bacteria was gram negative. The type of hemolysis observed on the throat swab was beta hemolysis, more…
The purpose of this experiment was to isolate two unknown bacteria and perform a series of selective and differential tests to correctly identify each. After the bacteria was isolated a series of differential and selective tests following the dichotomous key attached were used to identify each bacteria. The Gram-positive bacteria were identified as Staphylococcus aureus with a positive confirmatory test, mannitol salt agar, showing consistent results as well for S. aureus. The Gram-negative bacteria were Pseudomonas aeruginosa with a positive confirmatory…
The purpose of the unknown bacteria lab assignment was to select an unknown bacteria culture and, through a series of metabolic tests, identify which bacteria genus resided in the pure culture received. A nutrient broth inoculated with bacterial culture (numbered 45, henceforth referenced as U45) was selected and a streak plate was made to isolate a pure culture for use throughout the assignment.…
The purpose of this lab was to determine the identity of an unknown bacteria slant culture using a series of differential tests. The tests used to identify the unknown bacterial culture included: Gram stain, mannitol salt agar, coagulase tube test, and an antimicrobial susceptibility test. The tests selected were based on the results of a gram stain.…
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, indole, urease, DNase, and coagulase.…
The plate count agar, CFC agar and cetrimide agar are used and provided different evidences on the isolation of Pseudomonas from the soil experiment. Firstly, the plate count agar is a medium for the enumeration of viable organisms in food, water, waste water and also from clinical samples, and thus it is non-selective to any species. Whereas the CFC agar is a selective agar which contains reduced amounts of cetrimide but also cephaloridine and fucidin are added to allow the isolation of most Pseudomonas species. If the Pseudomonas species are present, a blue-green or brown pigmentation under the daylight, or fluorescence can be taken as a presumptive evidence under UV light. In the experiment, we had observed the colonies under UV light and…
The purpose of this experiment was to find the identity two unknown bacteria in the given test tube.…
After the gram stain test I carried out a catalase test. This test was carried out to investigate if my unknown was streptococci (negative) or staphylococci (positive) and or micrococci (positive). The catalase test result indicated that my unknown was negative because no bubbles formed when I placed a loop of the organism into hydrogen peroxide.…
An unknown labeled with number 8 was given out by the lab instructor. The goal at this point was to determine unknown gram positive vacteria. The procedures performed consisted of sterile technique in addition to being followed as stated in the referenced course laboratory manual by Matar (1) , unless otherwise noted.…
Coccus is a term used to describe a type of morphology that helps us distinguish different kinds of bacteria. The cell’s morphology is only one of the many ways we can differentiate the different species. Looking at these bacterium underneath the microscope is an important step to determine which kind of species it is. All cocci bacteria are not gram positive, but this lab will examine only this kind because of their influence in human health.…
The secretion yielded gram-positive cocci after 2-day incubation at 37°C on 5% sheep-blood agar under anaerobic atmosphere.Biochemical testing gave a positive result of α hemolysis and a negative result for production of catalase. The cocci wereidentified by using the BD Phoneix-100 system (Becton Dickinson, New Jersey, USA) as Alloiococcus otitis, by using VITEK 2-compact system (bioMérieux, Lyons, France)as Micrococcus Kristinae, and by using matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (Bruker, Leipzig, Germany) as “not reliable identification”.Sequencing the 16S rDNA PCR product obtained from the isolate yielded 1406/1419 bases (99%) sequence similarity with the homologous sequence of D. pigrum reference strain (GenBank accession no. X70907.1) by BLAST analysis…
My journey to the unknown started about three weeks before the end of my microbiology class at Brunswick Community College. This journey started out with a media plate cultured with an unknown species of bacteria. I was then instructed by my professor to use all of my previous knowledge to identify the unknown bacterial pathogen. This lab led me to master my skills of using the Gram stain, testing for catalase, testing for coagulase and using the oxacillin screen. Now I am going to take you with me on the journey to the unknown.…
The core difference between a gram positive bacteria and gram negative bacteria is the differences in cell wall composition. Prokaryotes known as eubacteria have three basic forms: rods, cocci and spiral. The bacterial cell wall is the single most important contributor to cell shape. In addition to shape of cell wall, presence or absence of flagellum, and if present, positions of flagellum, the eubacteria can be classified according to Gram Stain.…
In order to be able to adequately study and characterize a certain microorganism, microbiologists need to separate and isolate this microorganism from the many other microorganisms with which it usually shares its natural environment or habitat; proper and professional execution of bacterial isolation techniques are at the centre of routine activities in any professional microbiology laboratory. The task of the microbiologist is to isolate the microorganism under investigation from the mixed culture of the sample and to create a pure culture. A pure culture is defined as a population of cells which arose from a single cell by repeated cell division.…