The Gram-stain helped eliminate three out of the five challengers immediately because it was a Gram-positive rod. The test results lead to this identification by the process of elimination. A 2009 study compared the density of spores found in soil ~10 6 spores per gram to that found in human feces ~10 4 spores per gram. A member of the genus Bacillus, B. It is characterized by nausea, vomiting and abdominal cramps and is the emetic short-incubation form of the disease 3.
Dehydrated foods may be stored at room temperature and shipped without refrigeration. 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. After inoculating the paper with the unknown and dropping sterile water on top, the test was read within a fifteen second period to avoid false positives. Further, streptococcus is also identified by thr following tests: 1. The Controls are mixed in with the real samples so the analyst does not know which are which. MotP a MotA homolog , together with MotS a MotB homolog forms the stator of the sodium-driven motor.
The red coloring of broth turned yellow revealing acid production, and a bubble present in the durham tube represented the presence of gas. These basic characteristics are shared with other members of the B. The next tests performed were a Glycerol test and a Maltose test. Bacillus subtilis is part of group 1 and is strongly linked to B. This weak base raises the pH of the media above 8. The first step performed was growing the unknown on a Nutrient Agar plate in hopes of successfully separating the two bacteria.
This ruled out all of the cocci bacterium. Lactose fermentation is a characteristic of both E. Escherichia coli is capable of fermenting glucose as are Proteus mirabilis far right and Shigella dysenteriae far left. It was not until the last test performed, the Simmons Citrate Test, that the Unknown B bacterium was possible for identification. I would also recommend Bergey's Manual of Deterministic Bacteriology. The other possibilities were cocci shaped.
It is a rich, complex medium that contains 5% sheep red blood cells. This test was followed by a Casein Test which also turned out negative. Incubate slants 24 h at 30°C. This gas is trapped in the Durham tube and appears as a bubble at the top of the tube. .
The absorbance of this starch-iodine complex Hopkins and Bird, 1954 was checked for various iodine concentrations to ensure its linearity 2. Shake tubes vigorously and observe for growth as indicated by increased turbidity and color change from red to yellow, which indicates that acid has been produced anaerobically from glucose. Dry slide without blotting and examine under oil immersion for presence of free spores and darkly stained tetragonal diamond-shaped toxin crystals. The endospore is formed at times of nutritional stress, allowing the organism to persist in the environment until conditions become favorable. In the oxidase test, artificial electron donors and acceptors are provided. Table 1 and 2 lists the test, purpose, regent, observations, and results. This alone did not narrow down the field because every possible Gram-negative bacterium was rod shaped.
These compounds are small enough to pass through the bacterial cell wall. Rings of hemolysis are evident all around S. Pseudomonas aeruginosa is an example of a nonfermenter. This test was then followed by a Casein Test to see if casease was produced. The only two possible remaining bacteria were Bacillus cereus and Bacillus subtilis. Proteus mirabilis pictured here, second from right is a glucose positive, lactose negative, sulfur reducing enteric.
Spirit blue agar contains an emulsion of olive oil and spirit blue dye. Soil simply serves as a reservoir, suggesting that B. The Methyl Red Test was then followed by a Casein Test to see if the enzyme casease was produced. With no change in color the negative glycerol test suggests the bacterium is B. Inside the agar, oxygen is limited and usually it will move toward the surface where it is more oxygenated. The following table and flowchart convey the results.