Thus, these bacteria produce an acid slant and acid butt. It is often used to differentiate between members of Enterobacteriaceae. After pinpointing it was a Gram positive rod, a Simmons Citrate Slant test was conducted as well as other tests stated in table 2. A milk agar plate was inoculated with the unknown isolation of bacterium because it differentiates by the production of the enzyme casease that hydrolyzes the milk protein casein. Ferments mannitol: Organism: Bacillus subtilis b. The agar with gelatin will become cloudy 4.
Cells observed in a variety of polymorphic forms: X, Y and V shaped very common. Once it was confirmed that the gram positive bacterium was isolated, two tests were run. In such cases, the organisms should be considered positive for glucose fermentation yellow butt. This result now eliminates E. It was then observed that there was heavy growth on the plate with a clear ring around the colonies.
Because the same pH indicator phenol red is also used in these fermentation tubes, the same results are considered positive e. Some strains are harmful causing foodborne illnesses in humans, while other strains can be useful as probiotics for animals 2. Phenol Red Broth This is a broth to which a carb such as lactose or sucrose is added and there is a durham tube that is used to indicate gas production. The organism pictured on the far left is positive for hydrogen sulfide production. The emetic syndrome is caused by a heat-stabile toxin called cereulide that is found only in emetic strains and is not part of the standard pathogenesis of B. For the methyl red test, five drops of pH indicator methyl red is added to one of the tubes of medium.
This enzyme detoxifies hydrogen peroxide by breaking it down into water and oxygen gas. . An endospore is a dormant, tough, and non-reproductive structure produced by certain bacteria from the Firmicute phylum. The bubbles resulting from production of oxygen gas clearly indicate a catalase positive result. Both the emetic and diarrheal forms of the illness usually lasts less than a twenty-four hour period after invasion 3. Introduction The purpose of this study is to differentiate and identify two unknown organisms provided by the instructor in a nutrient broth.
It tests the ability of an organism to do several things: reduce sulfur, produce indole and swim through the agar be motile. Rub inoculated swab over agar blood agar surface of quadrant 1; discard swab and tongue depressor in vesphene beakers on bench tops 3. Compare your throat culture to demo plates 6. The isolation of Klebsiella pneumonia and Bacillus cereus was performed using the techniques and media studied previously in this microbiology class. The five sets of results contradicted each other.
However, the same strain produced cytotoxin in whipped cream at 8 degrees C. Then if the food is left at room temperature for a while before being consumed, like at a buffet or picnic, the endospore can come back to life and start multiplying. Despite not being part of the natural microflora in the human gut, B. Obtain Dubos agar plate; label plate with W,I,L, and N with a control in the middle 2. If the bacteria on it can ferment the lactose, the acidity turns the dye into a bright pink color.
It is commonly used to identify members of the genus Enterococcus E faecalis and E. A spore stain was not done, however positive result for the starch hydrolysis test leads to the final conclusion that this unknown is Bacillus cereus. Ferments Lactose: Go to Section D 2. After incubation, these tubes are first inspected for the presence of gas in the Durham tube. It has a very quick onset and usually resolves within several hours.
Toxin production at 8 degrees C was evaluated in two different types of commercial cardboard milk packages by inoculation with a potent toxigenic dairy isolate. There was heavy gray growth on this enriched medium. B cereus is a facultative anae … robe, and its bacterial growth generally occurs around 10-50 degrees celsius. Coagulase test Coagulase is an enzyme that clots blood plasma. Specimen 1 initially appeared to be gram-positive diplococci.
If you did not perform the test properly example: you drank a lot of fluids before taking the test, which can dilute your urine. Clinical Infections: Symptoms of the diarrheal-type syndrome include abdominal cramps and diarrhea after an 8 to16 hour incubation period. These plates were all done in order to isolate the two bacterium from each other. The inclusion of sucrose permits separation of certain Proteus organisms which ferment sucrose from the salmonellae since both of these groups of organisms are lactose-negative and both may produce hydrogen sulfide. Motility agar is a differential medium used to determine whether an organism is equipped with flagella and thus capable of swimming away from a stab mark. This will produce amine groups and cause the medium to turn alkaline.
Organisms capable of fermenting this sugar will use it up within the first few hours of incubation. Get four tubes phenol red glucose, lactose, sucrose, and either grape juice or milk for each organism- Bc, Ec, Cf, and Se 2. It is commonly used to distinguish the genus Proteus from other enteric bacteria. H 2S not produced: Go to Section D. Bacterium 2 was inoculated onto a blood agar plate using a sterile loop. At this point, when the glucose has been all used up, the organism must choose another food source.