Blood Agar Lab Report

After a gram stain was done unknown #257 was identified as a gram positive organism because when observed under the microscope the organism appeared purple with cocci in clusters. The organism was also catalase positive which means that it produced enzyme catalase and bubbled when hydrogen peroxide was added to it.
Three test were conducted based on the result of the gram staining procedure. Blood agar with a Novobiocin disk was chosen as well as DNase (DNA) and Mannitol Salts (MSA) agar. The Blood agar is a bright red, opaque plate and the streaking or the inoculation technique was a modified streaking for isolation with a heavy quadrant one. This is where the antibacterial disc bacitracin was used to determine the bacteria’s susceptibility.

The streaking technique used was a modified streaking for isolation with a heavy quadrant one. The result revealed that bacteria is alpha, with an incomplete breakdown of the medium with a susceptibility of 17mm from the bacitracin gamma hemolysis. That is why the organism represented by the bar graph was in low numbers because it was incomplete. The other test was DNase agar, it is an enzyme test used to identify if the organism has the enzyme DNA. The streaking technique is a single straight line down the middle of the plate. The unknown #257 tested positive for the enzyme DNase. Lastly, Mannitol Salt Agar (MSA) was used to test for isolation and differentiation. The streaking technique used is streaking for isolation.The unknown #257 tested positive for mannitol fermentation which means the organism is

SIM tube was used as well as the Triple Sugar Iron (TSI), MacConkey agar (MAC) and Citrate Slant. The SIM tube is used to identify hydrogen sulfide production, indole, which is a by-product of tryptophan which is broken down by tryptophanase and motility. The streaking technique used is a half stab. The TSI has an orange color and it used to identify carbohydrate fermentation specifically glucose, lactose, and sucrose fermentation. The TSI is used to observe the slant and butt of the tube as well as to identify if gas was present and if the organism produced hydrogen sulfide. The Another medium used was MAC, it is used to isolate and differentiate gram-negative organisms and it is a pink, dusty rose color. Lastly, the Citrate Slant is a green color and it was used as a differential test to examine enzymes. The media were inoculated at 37°C for 48 hours, then it was observed to determine the