Staphylococcus aureus - this is the raw data that you will use to create your lab report that is submitted. Part 1- Isolating S. aureus from your pudding sample Table 1: Fill out the following table using the DIFCO manual to determine what you would expect to see on MSA, BP, and VJ (selective & differential medias) for S. aureus Agar Initial colour Selective Ingredient Mannitol Salt Agar Light red to littler darker red Sodium chloride Differential Ingredient & Indicators D.I .: Mnnitol Indicator : phenol red Baird Parker + Egg Yolk Yellow Tellurite, Egg yolk Sodium pyruvate, glycine , lithium chloride Vogel and Johnson + Potassium Tellurite Red Indicator : phenol red Potassium tellurite, glycine, lithium chloride, mannitol Expected colour reactions Yellow colonies on MSA Black coloured , shiny and convex colonies Surrounded with zones Black colored colonies on yellow agar Table 2: After performing the experiment, you observed the following results for your pudding sample. Indicate whether these results are what you expected, and report the final reportable counts for each media Agar Counts & Final Answer CFU Reportable Count 3.750*10^3cfu/ml Colony colour, agar colour, acid fermentation, metallic sheen, etc. Yellow colonies on yellow agar MSA 75 BPA + Egg yolk 99 Black colonies on yellow agar, with a clear halo around the colonies 4.950*10^3cfu/ml Was this expected? Explain. Yes, it was expected as fermentation of mannitol occurred and due to the indicator phenol red, colonies changed color to yellow. Expected result due to clear zones around the colonies resulted from egg yolk.
VJ + Tellurite 83 4.150*10^3cfu/ml Black colonies on yellow agar Calculation hint: You plated fi.2mL! Recall formula ... (CFUft (volume plated x tube dilution)) Expected result as organism reduced potassium tellurite thst indicated black colonies while mannitol fermentation show yellow color. From which selectiveftdifferential agar plate would suggest performing biochemical (identification) testing for S. aureus? Suggestion : I would suggest BPA+egg yolk for further biochemical testing as it helps to differ coagulase and staphylococci. Part 2- Identifying S. aureus from pudding sample using biochemical testing Table 3: Before performing biochemical testing to confirm whether you successfully isolated S. aureus from your sample, you need to research what your expected results would be. This will help you determine whether your results match was what expected, and confirm whether S. aureus was isolated from the Agar Expected Results Results Do your results match what was expected? Explain. Gram stain Gram positive cocci in chains TSA Isolated colonies that can be used for biochemical test . Isolated colonies seen. Used for biochemical testing BHI Turbid growth in the tube in comparison to uninoculated tube . Turbidity in the tube s. aureus are gram positive cocci. Expected result as bacteria is gram positive cocci. Expected result and can be further used for biochemical test . Expected turbid appearance.
Catalase Positive catalase with bubbles . Bubbles Thermo- nuclease Coagulas e Pink color expected Clot formation expected due to coagulase positive nature of S.aureus . Part 3- Discussion No color was