Microbiology Unit 9 Lab Report

The following tests according to the lab manual were performed: gram stain, fermentation tubes, methyl red, vogues proskauer, sulfur, indole, motility and growing it up on MacConkey agar. The gram stain was performed incorrectly the first time. This is because the decolorizer was not on the bacterium slide for long enough, giving a false outcome.

4. While the reaction was still occurred, lighted a wood splint and quickly placed the burned splint in the mouth of the test tube. Do not put the burned splint into the acid solution.

This experiment was centered on metabolic and biochemical testing procedures. The rationale of performing these tests was to distinguish six different microbes from one another and to compare how their metabolic and biochemical processes differ from species to species to determine the unknown sample.

Nitrate reduction was tested for by inoculating a nitrate broth with the unknown gram (-) culture, and allowing growth to take place. Adding 2 drops of both sulfanilic acid and α-napththylamine to the medium if the first test to see if nitrite is present. If nitrite is present, the medium turns red, indicating a positive test. However, if the medium does not change, a second test is performed to see if nitrite was further reduced. In this second test, zinc powder is added to the broth to catalyze the reduction of any nitrate present to nitrite. If nitrate is present when the zinc is added the reduction of this compound will cause the medium to turn red, from the previously added reagents. Red medium on the second addition indicates nitrate was not reduced and a negative test result. However, if the medium does not change after the addition of the zinc, the unknown is positive for nitrate reduction, as the nitrite has just been further reduced, preventing its detection. The result that yielded was positive on the first step.

|EMB Agar | |Distinguishes bacteria that ferment |Dark blue colonies with|E. coli and P. |

Citrobacter Freundii is a species of bacteria that can be potentially harmful to humans. It is known to cause meningitis by protruding into the brain and replicating itself (1). The Citrobacter species has also been found as a cause of some urinary tract infections, diarrhea, and even gastrointestinal diseases and symptoms (3). C. Freundii can be located in a wide variety of soils and water (3). Lastly, it is also the cause of many nosocomial infections due to its presence in water (1).

The IMViC test is a series of different tests that differentiate between enterics. One is the Indole test. This test tells whether the bacterium possesses tryptophanase which is the enzyme that breaks down tryptophan into indole. The agar contains tryptic soy broth so if the bacterium contains tryptophanase, indole is produced. This production of indole is seen by adding Kovac’s reagent which causes a red ring to be seen at the top of the tube. The citrate test is also used to see which kind of products the bacteria make. It uses a green agar slant that contains sodium and ammonium phosphate. Bromythymol blue dye is late added as an indicator. Inoculation of the slant with a needle using a zig-zag then stab technique was used with the gram positive bacterium. Conversion of the medium to blue is a positive citrate result. All plates, slants, and broths were incubated at 37°C for 24‐48 hours.

This test is for only gram positive bacteria; unknown species B. Using a starch agar plate inoculate gram positive bacteria onto it. Make any kind of design on the starch agar. Label the plate starch agar and unknown species B. Incubate the starch agar for at least 48 hours at the 25C. After incubation open the agar plate and cover the entire surface with iodine and allow it to soak into the agar for 5 to 10 minutes. If there is a clear zone around the growth pattern or halo this means, there is no starch present and the bacteria have consumed the starch. Having a clear zone or halo means the test is

The first method is the pyrogallic acid technique in a solid medium. This technique uses streak cultures on nutrient agar slants. A person pushes a cotton plug into the tube until it almost touches the slant. The space above the cotton gets filled with pyrogallic acid crystals and put sodium hydroxide in there as well. Insert the stopper very tightly and then invert and incubate. The chemicals absorb the oxygen which produces an anaerobic environment. The second method is the shake-culture method in a solid medium. This is a molten and cooled nutrient agar which is inoculated with a loopful of an organism. The tube gets shaken, cooled quickly, and then incubated. The position of growth in the tube makes it the index of gaseous requirements for an organism. The third method os the Paraffin plug technique in a broth medium. It is a medium that has reducing substances like cystein or ascorbic acid in it. This medium gets heated to make the oxygen go away then get quickly cooled and inoculated with a loopful of culture. After that it get immediately sealed with melted paraffin and then gets incubated. The last method is fluid thioglycollate in a broth medium. It is present in redox potential indicator like resazurin, which produces a pink color in an oxidized

Chemical methods of control: Antimicrobial drugs, involves the use of chemicals to prevent and treat infectious diseases. Pasteur and others observed that infecting an animal with Pseudomonas aeruginosa protected the animal against Bacillus anthracis. Later, the word “antibiosis” (against life) for this inhibition and called the inhibiting substance “Antibiotic”. As researchers found out more and more about these chemicals they were able to discover that antibiotics are chemicals or natural substances such as bacteria, fungi, as well as synthetic drugs; that inhibit or kill microbes in small amounts. Chemotherapeutic agents are antimicrobial chemicals (natural or synthetic) that can be used internally or may be absorbed.

Procedure: Obtained a small Styrofoam cooler placed two small light bulbs in side and observed temperature over 24 hours to ensure temperature could be maintained between 98-100 degrees. Using a 10% bleach solution I then cleaned my work area. Transferring one capsule of L. acidopholis into a tube of MRS broth using the aseptic transfer technique then marked a line on test tube to record sediment. Labeled tube of nutrient broth S. epidermidis, then using a sterile swab obtained sample of

To begin with, we gathered fifteen test tubes in our test tube rack: three arabinose (A), three glucose (G), three mannitol (M), three raffinose (R), and three nitrate broth (N) tubes. We then labeled each test tube with either A, G, M, R, or N on the top of those tubes. Next we labeled these tubes with our initials, the date, and either Escherichia Coli or our unknown bacterium number. We did this so we would know which tubes to inoculate with E. Coli or our unknown and so we would know which tubes are ours. With that, we began inoculating the tubes with one loopful of E. Coli to one set of tubes in the order N to R to M to G to A. We flamed each tube before and after each inoculation in order to maintain aseptic techniques. This step was repeated two more times with each of our unknown bacteria. Finally, all of the tubes were incubated at thirty degrees Celsius. After a week on incubation, we added six drops of naphthylamine and two drops of sulfanilic acid to E. Coli N tube and our unknown tubes. This was to test for a positive

Transformation of cells was done by inserting the exegonous genetic material from different source (environment). Then, it was inserted into the host. This process will make the host cell transformed into competent cell. The exegonous genetic material is particular genetic material that express important protein or resistancy towards particular things. For example, in this pratical the E.coli was transformed into competent cell by inserting plasmid that can develop resistance toward ampicillin. Normally E.coli cannot live on the media that containing ampicillin. By referring to the genetic expression of cell, the genetic material of bacteria, which is plasmid will express the protein and develop resistancy. This is what called transformation of competent cell.

After exposure they are incubated along with an unexposed or control group of spores for the same period of time. If sterilization has occurred the spores which were exposed will not multiply. The control group should grow microorganisms and display a change in color. If this does not occur, then it’s spores have been inactivated and the test is invalid. This is because if the control spores were inactivated, it is possible the spores which were exposed also became inactivated prior to sterilization. Every item sterilized in the load with the indicator involved in an invalid test is considered unsterile. This is the case whenever there is an uncertainty about either the indicator of the control.

Environmental microbes are microorganisms that are capable of adapting and occupying a wide range of environmental conditions. Their biodiversity is well represented within the three major domains of life and can even extend into the ambiguous realm of viruses. As their categorical name indicates, environmental microbes can be found distributed throughout distinct ecological niches and based on their specific biological interactions within each ecosystem microbes can confer beneficial, adverse or neutral consequence to other surrounding life forms. In this experiment, we are interested in analyzing the air samples within the MIC 104 laboratory in order to determine the abundance of airborne species. Based on the biological restrictions imposed by the laboratories relative aseptic