Table 1 and Table 2 list the tests performed, purpose, and results. Returning to the original unknown stock 123, a quadrant streak plate was done with a sterilized inoculating look on a mannitol salt agar, which inhibits the growth of gram negative bacteria. Some problems encountered on this activity is the handling and contamination. Each of the four Gram stains showed positive rods. The purpose of this is to stain the bacteria.
The wrong interpretation of data especially from carbohydrate fermentation was challenging. For the first colony that was isolated from the unknown tube, the gram stain test determined that the bacteria were Gram negative rods. An aerotolerance test determined that the bacterium was a facultative anaerobe. The only problem that was encountered appeared when trying to isolate the gram positive bacteria. However, the same cannot be said for the other half of the unknown 113.
A sample was taken from this colony and transferred to a nutrient broth agar to further isolate it. The color that been produced was hard to distinguish because the yellow orange and red was look similar. All of the biochemical tests worked well except for the lactose and sucrose, its produced acid and gas. The methods that have been learned thus far for identifying bacteria have been applied to this unknown. Unknown test tube 25 was obtained and streaked onto two agar plates to obtain individually… study was to identify the unknown bacterium using biochemical tests and various methods that had been learned from previous the microbiology laboratory class. Twenty percent of the human population are carriers of S aureus, which can be found on the skin and inside the nasal passages. Afterwards, the bacterium was determined to be positive for lysine decarboxylation and citrate.
The two bacteria that give a positive result for this test are Staphylococcus aureus and Staphylococcus epidermidis. What are the 3 types of blood agar results and how can you recognize them? Over the course of a couple weeks, ten tests were performed. To avoid the spread and contamination of P. This eliminated two bacterium: Enterobacter aerogenes and Pseudomonas aeruginosa, leaving E. First, a gram stain was performed, indicating the bacterium was gram negative. Retrieved December 2, 2013 , , , ,. The reason for identification of unknown bacteria was to help students recognize different bacteria through different biochemical tests and characteristics.
Standard Methods Agar and Blood Agar Bases are examples of general purpose media. Some of these organisms have distinct qualities that set them apart from one another, such as the exposure to certain environments. The streak plate method utilizes an inoculating loop, sterilized by a Bunsen burner provided, to decrease chance of contamination on the nutrient agar plate 2. There are many reasons as to why this is important such as knowing what agent is causing a disease and the correct treatment is determined, to knowing which microbes are beneficial to a person and important to body functioning. The mixture was soaked with Crystal violet for 30 sec.
Not all of these tests were performed on every culture, as some were used only for gram positive or gram negative bacteria. Procedures were followed as stated in the lab manual 1. Upon observation the isolation plate showed growth of two different colonies. The other bacteria which was microscopically viewed as gram positive was missing in the incubator, another tube of sample was derived from the lab professor. Next, a negative result in the methyl red test indicated that no mixed acid fermentation occurred. .
A negative nitrate test ruled out E. The bacteria was tested on the mannitol test and turns read mannitol to yellow. This study was done by applying all of the methods that I have been learned so far in the microbiology laboratory class for the identification of an unknown bacterium. The Phenol Red tests—in which samples of the pure culture were mixed with broths containing Phenol Red and differing sugars—produced a yellow color and a bubble in the Durham tube Fig. One way this benefits humans and animals is by producing vitamin K2 2.
An estimated twenty percent of people naturally have harmless Staphylococcus aureus on their skin and are long-term carries for Staphylococcus aureus. All of these tests were performed by the methods listed in the lab manual by McDonald et al. The gram - is redPositive of gram - bacteria. The process of identification was achieved by utilizing procedures learnt during the semester. The culture was then inoculated onto a Mannitol Salt Agar plate. As for a negative result, no color change. This process is also useful in the production of antibiotics on a larger scale.