Start studying Lab - Oxidase and Catalase. Catalase is an enzyme found in bacteria that catalyzes the conversion of . Microbiology Lab Quiz #4 Dr. Collins. Catalase and cytochrome c oxidase are two important enzymes, which in combination with other tests, are used for typing (species or subspecies identification). Biochemical Tests; Antimicrobial Susceptibility · Catalase Test · Coagulase Test · Oxidase Test · Rapid Strep A Test · Latex Agglutination Test · Gonochek- II Test The oxidase test is used to identify bacteria that produce cytochrome c (note: All bacteria that are oxidase positive are aerobic, and can use oxygen as a.
Two nutrient agar plates and twoMRS plates were used. These were labelled Subculture of nutrient broth The nutrient broths were streaked as follows. The jars were shaken and then streaked onto two nutrient agar plates. The plates were incubated at room temperature for two days. Only one plate returned any useful colonies to test. So half of each colony was streaked onto a nutrient agar plate and the other half streaked onto a MRS plate.
Four nutrient agar plates and four MRS plates were used. Microorganisms only grew on the nutrient agar plates and these were labelled A-D.
Microbiology and Immunology Overall Structure - Structure: Whole Paper
Isolation of pure colonies and inoculation into broth For each pure colony found on the plates A-Da colony was inoculated into a nutrient broth. Next, without burning the loop, a nutrient or MRS agar plate was streaked. In this study, four nutrient agar plates, four MRS agar plates and 4 nutrient broths were used. These plates were then incubated at room temperature for two days.
Gram stain A gram stain 20 was conducted on each pure culture dish that had white bacteria growing.
Biochemical Characteristics of Micro-bodies: Peroxisomes and Glyoxysomes (With Diagram)
Yellow cultures were disregarded as they were identified to be yeast Since yeast is a fungus, the biochemical tests performed would not be appropriate. There were a total of four pure cultures. This stain is used to determine the make up of the cell membrane of bacteria. Gram positive bacteria stain a deep purple indicating they have a thick outer layer of peptidoglycan. This stain is also useful in determining morphology. Catalase test From each pure culture of white bacteria, a catalase test was conducted This biochemical test detects the presence of the enzyme catalase, which is present in aerotolerant aerobic bacteria.
An end product of aerobic respiration is the toxic compound hydrogen peroxide. The enzyme catalase reduces hydrogen peroxide to water and oxygen, and may be represented by the following balanced equation: Catalase positive bacteria will produce bubbles of O2 when H2O2 is applied. Lactic acid bacteria do not contain catalase, they contain peroxidase. Catalase negative bacteria have a delayed reaction or no reaction as peroxidase reduces H2O2 to H2O.
Oxidase test Using one colony from each plate that contains a pure culture of white bacteria, an oxidase test was conducted This biochemical test identifies if cytochrome c, a haem-containing protein required for respiratory metabolism, is present in a bacteria in its oxidised form Due to the presence of Fe, a platinum loop was used, otherwise the Fe in the loop reacts with the tetramethyl—p-phenylene diamine TMPD giving a false result.
When the bacteria is applied to the TMPD, if it is oxidase positive a blue colour will be produced. If it is oxidase negative, no colour change will occur or there is a delayed colour change of over one minute.
Subculture of the control and biochemical tests To obtain a control bacterial sample that is known to be Lactobacillus, a pure colony was streaked onto one nutrient agar plate and one MRS agar plate and incubated at room temperature for two days.
The pure colony was used to conduct a gram stain, catalase test and oxidase test, Hugh- Leifson and spore stain. Hugh- Leifson oxidation-fermentation test The Hugh-Leifson test indicates the metabolic process undertaken by bacteria; oxidation, fermentation or peptone utilising. If the original green media turns yellow all the way through, fermentation is occurring as it can occur in aerobic top of the tube and anaerobic bottom of the tube conditions. If the top quarter of the tube turns yellow, oxidation is occurring as O2 is available at the top, but it is anaerobic at the bottom.
If the media turns blue, this means neither oxidation, or fermentation of carbohydrates is taking place; however, the bacteria are able to ferment the peptones in the media.
A positive result for Lactobacillus would be if the media turns yellow all the way through the tube as it can ferment carbohydrates in aerobic and anaerobic conditions. Spore stain Schoeffer and Fulton Using a pure colony of the Lactobacillus control, a spore stain was conducted according to Microbiological Methods The spore stain is used to determine whether the bacteria produce spores or not.
On the original plates, the white microbes were surrounded by the yellow microbes. The white bacteria formed small, smooth looking colonies, whereas the yellow microbes formed larger grainy looking colonies. The white colonies were biochemically tested, but not the yellow ones because yellow microbes indicate yeast and the odour being released was sour, which is characteristic of yeast. Results from biochemical tests The biochemical tests that were performed on possible Lactobacillus candidates returned the overall result of negative for Lactobacillus.
Refer to Table 1 for a summary of these results. The pure culture plate A was determined to be gram positive, catalase negative and oxidase negative chains of spheres. The relationship between the Krebs cycle and the glyoxylate cycle is shown in Figure Both cycles employ the same reactions to produce isocitrate from acetyl-CoA and oxaloacetate, but beyond this point the pathways differ.
In the Krebs cycle, isocitrate is successively decarboxylated, producing two molecules of carbon dioxide and succinate.
Instead of being lost as two molecules of CO2, the two-carbon glyoxylate condenses with another acetyl- CoA to form the four-carbon dicarboxylic acid malate.
The oxaloacetate may then be utilized in gluconeogenesis. Glyoxysome-containing tissues are thus able to convert simple two-carbon sources such as acetate into carbohydrate.
Distribution and Origin of Glyoxysomes: Reports have appeared in the literature from time to time indicating the DNA is present in glyoxysomes, raising the possibility that these organelles possess some degree of autonomy. However, this notion is not generally accepted. Glyoxysomes appear to be formed by a process similar to that which gives rise to peroxisomes see abovenamely, by the fission or budding of preexisting glyoxysomes.
Most if not all glyoxysomal enzymes are synthesized by free i.
In concluding this discussion of micro-bodies, it is important to note that some organelles fitting the general microscopic description of micro-bodies do not clearly fit into either the peroxisome or glyoxysome category when evaluated in terms of their enzymatic activities. It is entirely possible that micro-bodies may be associated with varying activities depending on the specialization of the cell and that micro-bodies exist whose actions and cellular functions remain to be determined.
It is clear that one cannot name particles solely on the basis of microscopic characteristics and expect that all function identically.