Unknown Microorganism

There are many reasons for identifying an unknown bacterium. The reasons range from medical purposes, such as determining if the unknown could cause ailments in living things or knowing what microorganisms are needed to make antibiotics. The experiment was done by applying methods in order to identify an unknown bacterium.

The colonies were smooth, translucent, and had a white brownish color. The Gram stain resulted in Gram positive cocci. After the Gram stain was completed, the bacteria were streaked on a Mannitol-Salt Agar plate and a Catalase test was performed. After these test were completed a Phenol Red Dextrose Fermentation tube was inoculated, and a SIM Tube inoculated.

The purpose of this study project was to carefully isolate and identify two unknown bacteria from a mixed culture. The ability to properly evaluate biochemical test results is also necessary for the identification to be successful. The goal was to apply all of the methods and techniques that have been learned in the microbiology laboratory course for the proper identification of unknown bacteria. A certain amount of bacteria that were used throughout the course were possible bacteria that could be found in a mixed culture. The bacteria that were identified in the mixed culture were Staphylococcus Aureus and Kocuria Rhizophila.

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

This experiment was conducted to find the genus and species of an unknown bacteria prescribed by the lab teacher, which was unknown bacteria GA3 in my case. Identification of unknown bacteria techniques are used on an every day basis to figure out what type of bacteria it is and to find the best method of how to treat a patient with this bacteria (1). All five “I’s” of Microbiology were used in the testing for the unknown culture. Inoculation was used several times to put the unknown culture into agar plates or into biochemical test tubes. After Inoculation of these tubes or plates, they always were placed into the incubator for further growth and development. Isolation was used to make sure we got the correct bacteria we were testing for. After each further isolation, we gram stained the culture and inspected the culture under a microscope to further help in the identification process of the unknown bacteria. Multiple tests were done on the unknown culture to make sure we were confident in what kind of bacteria the unknown was.

Table 3 shows Gram stain results that indicated C. Freundii as a gram negative bacterium in rod shapes scattered in singles and some in pairs. Each gram stain produced the same results. The Bartholomew and Mittwer method of endospore staining indicated that C. Freundii tested negative for endospore formation. Table 4 shows the biochemical test results of the unknown and the official test results for comparison.

There are many reasons for knowing the identity of microorganisms. The reasons range from knowing the causative agent of a disease in a patient, so as to know how it can be treated, to knowing the correct microorganism to be used for making certain foods or antibiotics. This study was done by applying all of the methods that have been learned so far in the microbiology laboratory class for the identification of unknown bacteria. The identification process can be completed with a series of deferential stains and biochemical tests. Creating a dichotomous key helps to limit the amount of biochemical tests done on an unknown organism and by observation

Microorganisms are both beneficial and harmful. These microorganisms are important to humans because they play a role in the ecology of life, by decomposing wastes, both natural and man-made, such as creating nitrogen fertilizer at the root zones of certain crops. Other several pathogens that can cause serious harm, even immediate death due to the diseases or disease causing products they produce. Overall, microorganisms play an important role in life.

The purpose of this study was to identify the unknown bacterium #305. This sample was collected from the urine of a 64 year old hospital patient named “Doris”. Several tests were conducted to determine the morphological and physiological characteristics of the unknown. These tests included but were not limited to: motility, gram staining, salinity tolerance, and fermentation of different substances. After assessing the observed results, the identity of unknown bacterium #305 was suggested to be Citrobacter freundii. The test results, with the exception of the urea test, were very consistent with the expected results.

The bases of this experiment was to discover the identify of the unknown from three possible specimens: Klebsiella pneumonia, Escherichia coli, and Enterobacter aerogenes. Utilizaing the T streak technique, the bacteria was isolated into pure colonies for further study. The Gram Stain method was used to identity the morhphology of the bacteria such as the shape and whether the bacteria was Gram positive or Gram negative. Biochemical test were also used to help identify the unknown bacteria. The biochemical test used was the Triple Sugar Iron Agar, Sulfur Indole Motility test, Methyl Red test, Voges-Proskauer test, Citrate test, Urease test, and the Gelatin test. After observing the morphology of the bacteria using the Gram Stain method and utilizing all the possible biochemical test, the bacteria was identified to be Enterobacter aerogenes.

Unknown 52 was observed under oil immersion using the bright-field light microscope 1000x magnification after conducting Gram stain technique. Escherichia coli (Gram negative rods) pre-prepared slide was the negative control while the Staphylococcus epidermidis (Gram positive cocci) pre-prepared slide provided the positive control in order to deduce the results of unknown 52. Unknown 52 exhibited purple color cocci which was consistent with S. epidermidis organism. It can be concluded that unknown 52 was a Gram positive cocci. The purpose of Gram stain technique was to identify the present or absence of thick peptidoglycan layer outside the cell (1). Gram positive organisms contain a thick peptidoglycan layer while Gram negative organism contains a thin

Isolation, gram staining and identification of the micro-organism is a basic diagnostic tool in clinical as well as in research. This method is useful in diagnosis and treatment of diseases. The gram staining is simple, least expensive and is rapid. It is useful in counting of total bacteria. Because of the staining, the gram positive and negative bacteria can be viewed under the microscope. The shape, size can be determined. The gram positive bacteria may lose the stain easily. The retention of stain depends on the age of the cell. Old cultures get readily decolorized. Yet, this method is feasible method for diagnosis of the minute

A 10-Fold Dilution Series process was necessary to examine the bacteria further. The materials needed included: one Bunsen burner, one inoculation loop, one BIC ® Multi-Purpose lighter, three sterile LB Agar Petri dishes, one bottle of sterile saline solution, one pipette gun, one canister full of sterile glass pipettes, a medium sized test tube track, and one plastic tub of medium glass test tubes. Next, one participant’s 10-Fold Dilution series was performed and three lines of ten medium test tubes were placed in the medium test tube rack. 9 ml of saline were put into each test tube. The gas for the Bunsen burner was switched on and lit it using the lighter. The inoculation loop was sterilized with the flame for a few seconds and then removed

Before testing was done both bacteria, Gram positive and Gram Negative had been inoculated in 3ml TSB for 24 hours at 37°C. After incubation and with the help of cotton swab 2 plates of Mueller-Hinton agar were heavily inoculated with Gram positive obtained from the skin and Gram-negative bacteria obtained from water respectively. Swapping was done by following the procedure stated in the lab manual, going back and forth across one half of the plate ensuring the entire area was covered, turning the plate 90o and swabbing from top to bottom and turning the plate one last time a further 90o and repeat the swabbing in the indicated manner. Eventually 12 paper disks containing enough of the antibiotic were placed on the possible cultures and left in the incubator for 24 hours at 37°C. After inoculation the diameters of the clear zones (zones of inhibition) around each McFarland disk were measured with a standard ruler to the nearest millimeter. The measurements obtained were matched against a chart to determine whether the bacterium was resistant, sensitive, or intermediate in susceptibility to the antibiotic used.

Biochemical tests are used to identify bacteria species based on their differences in their biochemical activities of different bacteria. To differentiate one bacteria from another, each species of bacteria has a well-defined set of metabolic activities. Bacteria can be differentiated in many ways. They can be based on structural differences or metabolic differences. Structurally, the Gram stain is the most fundamental technique in identifying bacterial species and was developed by Christian Gram in 1884. Gram negative bacteria can be distinguished from Gram positive with the presence of LPS, lipopolysaccharide and a thinner peptidoglycan layer which doesn’t retain crystal violet as well. For this experiment, an unknown bacterium was identified from a list of 32 clinically significant bacteria. It was first isolated onto a TSA plate and then through a series of differential and selective tests were performed to determine its identity to be Klebsiella ozaenae.