Staphylococcus and Streptococcus Lab Report Example | Topics and Well Written Essays - 1000 words

Staphylococcus and Streptococcus - Lab Report Example A petri dish containing 1 TSA 5% sheep blood agar was divided in half. A sterile swab was used to swab the throat and skin. A streak inoculation was performed for each sample on each section of the plate, which was incubated for 24 hours at 37 oC.   The resultant colonies were then tested for Gram staining and the presence of alpha, beta, and gamma hemolytic bacteria. This test was performed by observing the presence or absence of red blood cell hemolysis on sheep blood agar. The next test that was performed was the catalase test to determine the production of enzyme catalase. A small amount of the colony was placed on a glass slide after which a few drops of catalase reagent was dropped on the bacteria. The production of bubble indicated a positive test for catalase. The catalase-positive samples were then tested for bacitracin sensitivity by incubating the colonies in four sections of a blood agar plate containing bacitracin discs for 24 hours at 37 oC. A coagulase test was then performed following the observation of bacitracin resistance in the bacteria. This test was performed to detect the production of enzyme coagulase by adding a loop full of the bacteria to tubes containing rabbit plasma and incubating for 24 hours at 37 oC. The coagulase negative samples were further tested for novobiocin susceptibility by incubating the bacteria in plates containing novobiocin antibiotic disks at 37 oC for 24 hours. Novobiocin test is usually used to distinguish between S. epidermidis and S. saprophyticus.

Density of regular solids Essay Example | Topics and Well Written Essays - 750 words

Density of regular solids - Essay Example An analysis of the lab results shows that it fulfilled its purpose; it presents the densities of the materials obtained using different procedures. The objectives of this lab were, therefore, met, since, everything happened as expected. The  main  source  of  error  in the  experiment  is the  taking  of  measurements. The  error  due  to  direct  measurement  is  less  than that  due  to the  displacement  method; the values are 2.619 and 18.2  percent  respectively. The  difference  between the two is  so  big  that it  brings doubt into  the  suitability  of the  displacement  method  in  calculating  density. There is a  difference  between the  results  obtained  in this  experiment  and the  expected  results. For  instance, the  lab  results  denote  a  density  of 1.0408 g/cm3 for  water, while the  expected  density  under the  conditions  under which the  lab  was  conducted  is 0.991724 g/cm3. The  difference  might  have  come  about  due  to temperature and pressure changes in the lab. It might also have been caused by human error, especially during calibration and measurement. The lab exercise was successful; the density of the various compounds was established. I learnt the importance of taking precise and accurate measurements while doing experiments. The results of the experiment are entirely dependent on the procedure and accuracy of the measurements taken. I am, however, curious to find out how room temperature affects the density of a material. I hope to establish the facts about this issue in subsequent classes and, perhaps, lab