MIP302 Final Lab Exam (from Turned in Labs),

MIP302 Final Lab Exam (from Turned in Labs),In which environments will microaerophiles grow and not grow (Done in Lab) - answerGrowth in ambient air incubator and Candle Jar No growth in GasPak Jar In which environments will Facultative anaerobes grow and not grow (Done in Lab) - answerGrowth in ambient air incubator, candle jar, and GasPak Jar In which environments will Obligate anaerobes grow and not grow (Done in Lab) - answerNo growth in Ambient air incubator and candle jar Growth in GasPak Jar Catalase Test Results - answerbubbles: positive no bubbles: negative Cytochrome Oxidase Test Results - answerColorless: negative Dark blue color change: Positive Carbohydrate Fermentation-PR Broth Results -Lactose Fermentation - answerHot pink: Negative gas production-negative ferment lactose Yellow: Positive for gas production-positive for lactose fermentation Nitrate and Nitrite Reductase Test Results - answerColorless:Inconclusive after addition of Nitrate A and B Colorless (after zinc added): + for nitrate and nitrite reductase Red (after nitrate A and B added): + for nitrate and - for nitrite Red (after zinc added): negative for nitrate and nitrite reductase What compound is formed when oxygen in the broth is reduced? - answerH2O (Water) Why was C. perfringens grown in thioglycollate broth instead of TSB? - answerBecause it is an obligate anaerobe. Thioglycollate broth contain sodium thioglycolate, which decreases free oxygen in the media, which creates an anaerobic environment Imagine that you have a tube of water containing methylene blue dye. You inoculate the broth with 'active, dry' baker's yeast. The bakers yeast contains trehalose, which the yeast uses to grow in the water, using aerobic respiration. As the yeast cells respire, the water turns from blue to colorless. Why? - answerAs the yeast cells respire, the water turns from blue to colorless because the dye is initially oxidized because it hasn't received electrons from the yeast (inactive yeast), then as the yeast cells respire the dye gains electrons from the yeast and turns colorless Under aerobic conditions, some yeast cells use aerobic respiration and produce carbon dioxide. Under anaerobic conditions, these same yeast cells ferment carbohydrates to produce alcohol and carbon dioxide. These yeasts are unusual, because they are one of the very few eukaryotic organisms that are classified as __________ ___________, based on their oxygen requirements - answerFacultative anaerobe Human RBCs produce catalase. Based on this information, what do you think happens when hydrogen peroxide is used to clean a wound? Why? - answerBased on the fact that human RBCs produce catalase, when hydrogen peroxide is used to clean a wound it interacts with the catalase and the hydrogen peroxide converts it into water and oxygen, which will form bubbles An oxidase test has turned slightly pink after sitting on the bench for 10 minutes. Is this a positive result? Why or why not? - answerNo, this would not be a positive result because the oxidase test needs to be observed within 3 minutes. As the test sits on the bench for 10 minutes, it is absorbing O2 from the environment and makes the sample think it was oxidized Phenol red is incorporated in PR carbohydrate broth to detect the presence of __________ which is produced during ___________ of the carbohydrate in the broth - answer-Lactic Acid -Fermentation Assume that you have correctly inoculated a PR glucose broth. When you observe the broth after 18 hours incubation, it is a hot-pink color. Why? and is this positive or negative for glucose fermentation? - answerThe broth would turn hot pink if the bacteria began metabolizing the peptones and beef extracts in the broth, and alkaline by-products are produced turning it hot pink, due to an increase in pH -Negative Imagine that you correctly inoculated a PR sucrose broth with a bacterial culture known to be positive for sucrose fermentation. When you observe the broth after 36 hours incubation, it is a hot-pink color. How would you explain this result? - answerToo long incubation, which led to the bacteria utilizing all the carbohydrates and metabolizing the beef extract and peptones, which raised the pH of the broth and turns a yellow (+) result to hot pink (-) Imagine that you have inoculated a PR lactose broth with a pure bacterial inoculate. The broth turns a bright yellow color after 24 hours incubation. What does this result tell you? - answerThe bacteria did ferment the lactose, which produces acid and the broth becomes yellow What color was the nitrate control broth after the addition of Nitrate A and B reagents? Why was it this color? - answerColorless because the control would not contain nitrate reductase because nothing is being added to the control What color was the nitrate control after the addition of Nitrate A and B and zinc? Why was it this color? - answerRed because since it is acting as a control, it would not contain nitrate or nitrite reductase because nothing is being added TSA Agar Plates - answerTryptic soy agar, a type of microbial growth medium that allows growth of a wide variety of organisms MacConkey Agar Plates - answerGrowth of gram negative rods -Ferment lactose-red colonies surrounded by zone of precipitated bile salts -Non-lactose fermenters-colorless or transparent colonies -Inhibited growth of gram positive due to bile salts and crystal violet PEA Plates - answerInhibits gram negative and selects for growth of gram positive -Phenylethyl alcohol Pseudocel Plates - answerGrowth of only P. aeruginosa, which only bacterium to produce pyocyanin -Blue-green colonies Pseudomonas Agar F Plates - answerAll bacterium will grow -Only bacterium that produce fluorescein will grow and glow -Lime-green colonies not under UV light, then glow with UV light Beta-Hemolysis - answercomplete lysis of red blood cells; clearing Alpha-Hemolysis - answerincomplete lysis of red blood cells; no clearing; greenish-brown colonies Gamma-Hemolysis - answerNo media change Gram stained = purple and pink rods Both dark and colorless colonies on MacConkey Agar Plate -Growth on PEA plate - answerGram positive and gram negative bacilli bacteria What is the Gram reaction of the bacteria in the mixture-based on MacConkey of pink and colorless colonies? - answerGram negative for both bacteria because only gram negative grow on MacConkey agar plates and two colored colonies shown If Gram stain and the MacConkey agar plates don't match their results, which one would you trust? - answerMacConkey -PEA is not as stringent as MacConkey and you have to gram stain PEA to assure your results -In addition to this, there is more room of mistakes with gram staining and gram negative is the only bacteria that'll grow on MacConkey, so it's easier to interpret 2 results of MacConkey Agar plates? - answerLactose fermentation and gram negative rods How do you explain growth on the PEA plate? - answerPEA agar selects for gram positive bacteria and is most useful for the isolation of gram positive from a specimen that also contain gram negative organisms. Gram negative bacteria are inhibited and don't grow as vigorously Imagine that you have a mixed culture that you known contains both Gram negative rods and Gram positive cocci. You cannot isolate anything but Gram negative rods on TSA. What medium would you use to help isolate the Gram positive cocci? Why? - answerPEA because it selects for growth of gram positive bacteria and inhibits greatly the gram negative bacteria If MacConkey agar plates were made using phenol red instead of neutral red, what color would colonies produced by lactose fermenting bacteria be? Why? - answerThe colonies would be yellow because when acidic (lactose fermentation) they turn this color rather than red for neutral red acidic -They are opposite of each other for acidic/basic color change The blood agar plates that you observed were all inoculated with Gram positive bacteria. Would E.coli, or any other Gram negative bacterium, be able to grow on BAP? Explain. - answerYes becaus