Identification Of Unknown Bacteria Lab Report

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Not all of these tests were performed on every culture, as some were used only for gram positive or gram active bacteria. The tests performed and what constituted a positive or negative test are as follows: Lab day 1; today in lab we obtained the unknown mixed culture “041 “and one brain-heart infusion agar (BAA).

The first step was the preparation of the medium, the bottom of the BAA dish was labeled with the bacterium number, initials, and section; then divided into four quadrants.

The second step, we used the septic technique to transfer a small amount of culture with a flame-sterilized inoculating loop to the first quadrant, flamed and cooled the loop again then transferred a small amount of the culture from the first truant to the second using the quadrant streaking method as illustrated on page 18 of the lab manual, repeating this process until all four quadrants were properly streaked.

Lab day 2; we collected our BAA medium and began by identifying the morphology and cell-to cell arrangements of the colonies.

Two different colonies were observed, the first colony was yellow in color and larger in size and the white colored colony was slightly smaller in size. As instructed, each colony was prepared for gram staining, one slide for the large yellow colony and one for the smaller white colony.

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After properly gram staining the slides as directed in chapter six of the lab manual, the smears were examined under the microscope.

Unknown Bacteria Lab Report Gram Negative

The findings concluded that the smaller white colony stained purple, signifying that this culture was a gram positive bacterium, with the morphology of grape-like clusters such as staphylococcus. The larger yellow colony stained pink with the morphology of rod shaped bacterium, which indicates this bacterium to be gram negative. To isolate the two unknown microorganisms for further testing, another BAA medium was obtained, the bottom of the dish was vided into two sections and the lawn streaking procedure was performed, as illustrated on page 12 of the lab manual.

One side of the BAA medium was inoculated with the gram positive Cisco and the other side with the gram negative unknown bacteria, completing this section of lab by placing the labeled medium into the ICC incubator for 48 hours. Laboratory day 3; a series of tests that were specific to the unknown gram negative and gram positive cultures were performed. Only two tests were necessary for the gram negative bacteria, which included the Underwrote II and the Indolent Dressily test card.

Because immediate exults would be obtained from the Dressily test, this experiment was performed first by using a flame-sterilized and cooled inoculating loop to transfer a small growth from the gram negative colony to a clean reaction area of the test card. After 30 seconds, a pink color in this area was observed, indicating a positive result for indolent, the positive result was documented. After properly inoculating the Underwrote II as instructed by our lab instructor, the tube was labeled and placed it in the ICC incubator for 24 hours.

There were six different test media that were performed on the gram positive bacteria, starting with the inoculation f the imitation salt agar (MASS) dish, using a flame-sterilized and cooled transfer loop. Two loop transfers of our isolated gram positive bacterium were placed onto the surface of the agar, applying the quadrant streaking technique as illustrated on page 18 of the lab manual, labeled our medium and placed it into the ICC incubator for growth and interpretation. On the sheep blood agar (SABA), the flame-sterilized and cooled loop was used to transfer two loops of the gram positive bacteria to the media.

Only one-half of the plate was streaked, the inoculating loop was again and a small portion of the culture from the iris quadrant was used to streak the second quadrant, repeating this step to inoculate the remaining quadrant. Using ethanol-flamed forceps, one Backtracking and one Optician disk were transferred onto the one-half quadrant, spacing the two disks approximately two centimeters apart. In the last step, a flame-sterilized and cooled transfer loop was used to place three stab marks into the second quadrant the SABA media, labeled the dish and placed into the ICC incubator for 48 hours.

The Dense dish was spot inoculated by transferring one loop of the gram positive bacteria with the flame-sterilized and cooled inoculating pop to the center of the plate, the media was labeled and placed it into the ICC incubator for growth and future interpretation. The labeled Intercourse fiscals (FEE) broth tube was inoculated as well as the 6. 5%NCAA broth tube by removing the caps from the tubes and placing one loop of gram positive culture into each tube with the flame-sterilized and cooled inoculating loop, mixed the culture in to the broth and replaced the caps.

After labeling the bile esculents agar (BEA) slant tube, the cap was removed, one loop of gram positive Cisco was placed into the bottom corner of the slanted agar and the culture was streaked upward, towards the top of the agar, the cap was replaced and all three tubes were placed into the ICC incubator for growth and future analysis. For the final test, two drops of hydrogen peroxide (H2O) were placed on the isolated colony of the BAA medium, observed immediate formation of bubbles, as 02 was produced indicating a positive test for catalane.

Final lab day four; the test media were collected for explanation and interpretation, the results are as listed: Gram Negative Intercontinental Dressily test card Positive (+) slide took on a pink color Underwrote II – identification system Glucose Positive (+) color changed from red to yellow Lysine Positive (+) color changed from yellow to purple Ernestine change HAS Negative (-) no color change Indolent Positive (+) Admonition Negative (-) no color change Negative (-) no color Lactose Positive (+) color changed from red to yellow Rabbinate Positive (+) color changed from red to yellow Servitor Positive (+) color changed from red to yellow Dilution Negative (-) no color change Appalachian- Negative (-) no color change dominate Urea Negative (-) no color change Citrate color change Unknown 041 Gram Negative is Escherichia coli Gram Positive Cisco BAA (color) White BAA(colony size) Small Catalane Positive (+)formation of bubbles observed Dense Negative (-) no visible reaction to HCI Negative (-) no MASS (growth) Positive (+)visible bacterial growth observed MASS(imitation) Positive (+)partial color/pH change from red to yellow SABA(hemolytic) Gamma (y )no homologies produced Backtracking Negative (-) no zone of inhibition Optician Negative (-) no zone of inhibition Bile Esculents Negative (-) no color change FEE Medium Negative (-) no color change 65% NCAA Positive (+)broth appeared cloudy *Unknown 041 Gram Positive Cisco is Staphylococcus epidermises Discussion The identification of the unknown intercontinental 041 was fairly easy. Once the unknown had been identified as gram positive using a gram stain, there were only two tests used to narrow down the microbe’s identity. Based on the positive indolent test results, the bacteria identification was limited to two possibilities, either Escherichia coli or Protests vulgarism.

After carefully interpreting and recording the results from the Underwrote II and completing the customs key, the gram negative unknown was determined to be Escherichia coli. Identifying our gram positive unknown was a little more difficult due to the extent and various media tests that were involved. However, the positive test results observed for catalane, imitation, 6. 5%NCAA and the fact that there were no homologies produced on the sheep-blood agar (SABA), made it evident that the gram positive unknown was Staphylococcus epidermises. Conclusion The determination of the unknown mix culture “041” was achieved by using a variety of differentiation tests.