Petri Plate Discussion

3. Microbiologists employee a number of approached to acquiring a pure culture from a from sample containing a number of different types of bacteria. Briefly describe three different procedures commonly used to secure pure cultures from a mixed culture. The use of simple labeled diagrams may be quite helpful.

The next step of the project included preparing a Gram stain to discover the cell shape, arrangement, and if the bacteria is gram positive or

Often scientists work with bacteria that do not come in a labeled test tube— for example, bacterial samples taken from infected human tissue or from the soil—and the scientist must then identify the unknown microorganism in order to understand what behavior to expect from the organism, for example, a certain type of infection or antibiotic resistance. However, because of the relatively few forms of bacteria compared to animals and because of the lack of bacterial fossil records due to their asexually reproductive nature, the taxonomy used to classify animals cannot be applied to bacteria (Brown 275). In order to classify unknown bacteria, a variety of physiological and metabolic tests are available to narrow a sample down from the fathomless number of possibilities into a more manageable range. Once these tests have been performed, the researcher can consult Bergey’s Manual of Determinative Bacteriology, a systematically arranged and continually updated collection of all known bacteria based on their structure, metabolism, and other attributes.

There are many reasons for knowing the identity of microorganisms. The reasons range from knowing the causative agent of a disease in a patient, so as to know how it can be treated, to knowing the correct microorganism to be used for making certain foods or antibiotics. This study was done by applying all of the methods that I have been learned so far in the microbiology laboratory class for the identification of an unknown bacterium.

For the temperature treatment, it was decisive in that the A. franciscana showed a steady increase in concentration from section 1 to 4. This expands on the hypothesis that suggests A. franciscana prefers an optimum temperature between 20-24 ̊ C because from the results of the experiment A. franciscana seemed to prefer even higher temperatures. Al Dhaheri and Drew (2003) state that A. franciscana stop reproducing at temperature above 30 ̊ C and compared to the experiments results. It can be concluded that A. franciscana prefer warmer temperatures, but reproduce at lower

There are many reasons for knowing the identity of microorganisms. The reasons range from knowing the causative agent of a disease in a patient, so as to know how it can be treated, to knowing the correct microorganism to be used for making certain foods or antibiotics. This study was done by applying all of the methods that have been learned so far in the microbiology laboratory class for the identification of unknown bacteria. The identification process can be completed with a series of deferential stains and biochemical tests. Creating a dichotomous key helps to limit the amount of biochemical tests done on an unknown organism and by observation

The goal of this paper is to demonstrate comprehension which will fully explain why the test were chosen and how they were performed and lastly to to identify the unknown species. Material and Methods: A broth tube labeled as number 24 containing two unknown bacteria was given out by the lab instructor. To begin the identification of the unknown bacteria a streak plate was performed on a Tryptic Soy Agar (TSA) plate, using the quadrant method. The TSA streak plate was labeled at #24-1.

this means that is the optimal temperature, but in bacterial occur in less time than in fungal

For this particular assignment, I was given a slant with an unknown bacteria by my lab instructor. There were several procedures performed to identify the unknown bacteria. The first procedure was streaking tryptic soy agar plate (TSY). The purpose of streaking is to identify the bacteria in a sample presenting a pure culture of colony morphologies. After several hours of incubating the streaked plate, visual isolated colonies were present. The steps to streaking are as follows; Flaming an inoculation loop with a Bunsen burner until red hot, then allow to cool before taking the unknown bacterial sample. Streaking four quadrants onto the TSY medium plate by dragging the loop gently through first quadrant then sterilizing the loop by flaming it again. This procedure was continued into the third and fourth quadrant. The second procedure performed was the bacteria smear. The motive of the smear is to have the bacteria ready for a stain after it has been heat fixed on a slide. These steps conclude by first labeling the slide with the my initials, flaming the inoculated loop, then allowing the loop to cool before spreading the unknown bacteria on slide after instilling a drop of distilled water. This process took about 10 minutes for the wet surface to dry before heat fixing. Heat fixing is when a bacteria smear is smeared on a slide and dried at room temperature before passing a slide through a hot flame of a Bunsen burner. Soon after the slide had been heat fixed and

Although fungi are distributed worldwide, the distribution of a specific species is limited by temperature and moisture conditions of an area coupled with the available food supply. The best temperature for most fungi to thrive is from 68° to 86°F (20° to 30°C). Some types of fungi, however, do perfectly well at tem- peratures as high as 120°F (48°C), while a fairly large number of them do well at freezing temperatures, 32°F (0°C) or below.

A wide variety of processes had been performed to determine what culture had been acquired in class. My group had acquired culture tube unknown #3. We first isolated the bacteria. In this step we took the broth of the unknown #3 and grew it on an agar plate. The first process that had been performed was discontinuous streaking, and continuous streaking to grow the culture for future use in the lab and to have extra to perform a whole variety of test to determine the unknown. The next experiment that had been performed

In class, we were given the task of identifying an unknown bacterium broth culture. After receiving number 69, I went through several tests to figure out what bacterium I received. First, I created a slide from my broth by putting a small amount of the unknown broth on to a clean slide and letting it dry for ten minutes. After this, I stained the slide by applying four reagents in order; crystal violet, grams iodine, decolorizer and safranin. From the stained slide, I discovered that this bacterium was gram-negative, which would determine the next couple of tests I would do to identify my unknown bacterium. I began by streaking for confluent growth from my broth culture onto a TSA plate. From the TSA plate, I aseptically transferred a loop

The data can be seen in table 1, which represent morphology characteristics of the unknown. The structure of the cell wall of the unknown was determined by observing the Gram test. For this test Gram stain yielded pink coloration of bacteria, which states that the cell wall structure

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

These ranges are classed as cardinal temperatures and consist of minimum, optimum and maximum. The optimum is the temperature at which the bacteria will grow most rapidly, whilst temperatures below the minimum and above the maximum no growth will occur. (Prescott et al. 2008..) Growth rate decreases rapidly once temperatures exceed the optimal rate placing the maximum rate very close to it, whilst the minimum temperature is much further away from the optimum. (Ingraham et al..1990) The cardinal temperatures vary between each species of bacteria which places them into subcategories relevant to these experiments as shown below:-