Streak Plate Essay

Blood and saliva borne bacteria are mainly the reason for some serious infectious diseases (Szymanska, 2005, Martin et al., 2009). For example, Hepatitis B virus (HBV) is a known virus that may be contracted in dental clinics. Investigation of the presence of the virus in the oral fluids of hepatitis B carriers showed that %70 of their sample were infectious (Molinari & Harte, 2010). The greatest concentration of the HBV is under the gingival sulucs where this area is inflamed routinely and allows blood to mix

The three organisms that were identified in my unknown tube were Citrobacter freundii, Corynebacterium xerosis, and Micrococcus. The first step of this project involved isolating the three organisms that were within the mixed culture. Once I successfully isolated them, I was able to do specific colony morphologies for each of the organisms. The characteristics of Citrobacter freundii includes butyrous, opaque, circular, convex, and beige. Corynebacterium xerosis is white, small, punctiform, circular, dry, and brittle. Micrococcus is white, large, opaque, butyrous and circular.

It’s fascinating and a bit strange to think just how many bacteria live in our mouths, on our skin, and inside our bodies. Usually we think of all bacteria as being bad and harmful to us, but our bodies contain tons of good bacteria that play a very important

14. Use the same loop and technique to spread the same cell suspension (+) on the LB+AMP agar plates. Dispose of the sterile loop in a beaker of germicide.

1.2 ml of the bacterial cultures are taken to pellet the cells and remove supernatant while

The purpose of this experiment is to distinguish and indentify an unknown bacterium. There are several tests that can help one eliminate and narrow down the options. The most useful test, and the very first one done, is a gram stain. This test will tell whether the bacterium is gram-positive or gram-negative. After the type of gram stain is identified, the tester has a wide array of differentiating tests at their disposal. Based on the results from these tests, and the numerous others that are available, one can accurately establish the identity of an unknown bacterium.

There were two tubes used in this process: the tube that contained the primary culture and the tube that contained the nutrient agar where the unknown bacteria would grow. First, the inoculating loop was flamed. After removing the caps of both the test tubes, they were flamed to prevent contamination of the unknown bacteria. The inoculating loop was cooled for a few seconds and was then placed into the test tube containing the bacteria. The inoculating loop with the bacteria was placed into the nutrient agar test tube for cultivation. Before the test tubes were capped, they were flamed once again. Also, isolation of the unknown bacteria had to completed. Nutrient agar was placed in the petri dish, and was left to gel for a few minutes. After the agar gelled, the inoculating loop was used to acquire bacteria and streak the unknown onto the plate for

The objective of this experiment was to identify two unknown bacteria from a mixed culture. Which was done by using the aseptic technique which was very important to avoid any contamination and keeping the workspace clean while culturing bacteria for different tests. To start, I chose a tube which had a solution of mixed culture. I used the flame to sterilize the inoculating loop and dipped it into the tube and streaked for isolation on 2 TSA plates and placed them in an incubator at 37 for 24 hours. Next day I observed the growth of 2 different types of colonies one for each unknown on the two plates. So I picked the best one and labeled it as master plate and discarded the other plate. From the master plate, I subcultured each type of colony

The test tube was labeled with the bacteria identifying number. The cap on test tube was removed, and the lip of the test tube was flamed. Next, the Bunsen burner was used to sterilize the inoculating loop. Then, bacteria were picked up from the working plate with the loop and the agar was inoculated. The loop was then re-flamed. Finally, the plate was placed in the 37˚C incubator and left to sit for 48 hours and any changes in color were observed. A negative result appears green, and a positive result appears blue. This is because it tests for the organism’s ability to use citrate as its sole source of carbon, and if it does then it produces ammonia and ammonium hydroxide which make the medium basic, changing the green agar blue (Leboffe & Pierce,

Upon obtaining the unknown organism, it was important to make a streak plate of the bacteria on TSA. The purpose of doing so ensures that we have pure cultures of the unknown to be used in further testing and not a mixed culture. The first test used was a gram stain. It is a differential stain that helps distinguish between gram-positive and gram-negative

Flow Diagram Homework Assignment Name: Preetam Ganti Using the table below, explain the purpose of each of the steps of the Experimental Flow Diagram (Figure 1 from your lab manual – it is provided on the next page) for answering the two research questions guiding this laboratory investigation: 1. Is the bacterial contamination at these three farms due to the same plasmid or different plasmids? 2. What is the frequency of tetracycline resistant bacteria in the beef farm cultures?

2a. In the first part of the experiment, why did we put the donor on a plate containing nalidixic acid?

The petri dish lid was raised to insert the loop. The loop was touched to the agar area on the opposite side of the dish. The bacteria on the loop were transferred to the agar. The bacteria were spread in the first sector of the petri dish by moving the loop back and forth across the dish (zigzag motion).

Another purpose of this experiment is to stress the importance of knowing the identity of a microorganism. Knowing the species of microorganism present in a sample provides a

Bacteria vary greatly in terms of their characteristics and morphology. Colonies can be classified according to their colour, form, elevation, margin and size. Pure cultures of microorganisms