Nutrient Agar And Macconkey Agar

A mixed culture of two unknown bacteria was provided by the instructor. The methods used for

Read in your lab manual about the following agar mediums: Blood Agar (pg 168), EMB Agar (pg 170), Mannitol Salt Agar (MSA)(pg 172) ), MacConkey Agar (pg 174), and PEA Agar (pg 176) to answer the following:

Bacteria are ubiquitous; they can be found on the skin, in the soil, and inside the body. Because of the very nature of this ubiquity, it is important to be able to determine between different strains of bacteria. An example of this is determining the causative agent for a disease so that the patient will be treated with the appropriate antibiotics. It may be important to determine the bacteria in a certain region, because like with enteric bacteria, it is normal to find them in the digestive tract as they are in a symbiotic relationship with our bodies in this area; however, they also cause opportunistic infections in places outside of the digestive tract to our detriment, such as with a urinary tract infection. Some strains of bacteria are common to nosocomial infections, and identifying these bacteria as such helps create the guidelines for healthcare workers in antiseptic technique. All of the morphology and characteristics of each strain of bacteria help us to better understand the role of bacteria in the body as well as helps us understand how they can cause illness, and what treatment regimen to set in place. In lab this semester, a sample of unknown

The purpose of the following study is to determine where the two unknown bacteria acquired in Microbiology lab should be classified in regards to temperature, pH level, and osmoregularity. It is important to classify bacteria in order to identify them. Identification of bacteria is important because they are not only useful but potentially dangerous as well. The identification of bacteria can lead to breakthroughs in healthcare regarding treatment of old and new diseases alike. Identifying bacteria can also be used in many other areas from better crop production through microbial pesticides to biological warfare. Their uses are endless as are their abilities to evolve and adapt to changing environments. That is why it is so important

Background information: In this lab you will be looking at the growth of bacteria under different conditions to see the how populations of bacteria grow. Read about cells in the text or e-text. For everyone, in your e-text read chapter 13, sections 13.3 and 13.4 to learn more about bacteria. Then answer the questions below.

Bacteria are small, unicellular prokaryotic microbes. They have many morphologies, which include rod-shaped, spherical, spirals, helices, stars, cubes, and clubs. Classification of bacteria begins with either aerobic (requiring diatomic oxygen for growth) or anaerobic (not requiring O2 for growth). Bacteria can simply be narrowed down to gram positive (organism that stains purple or blue by Gram stain) or gram negative (organism that stains red or pink by Gram stain). Many physical and nutritional factors influence bacterial growth. Physical factors include temperature (psychrophiles, thermophiles, and mesophiles), pH (neutrophiles, acidophiles, and alkalinophiles), O2 concentration (aerobic

During the purification section of this lab, the LB/amp/ara agar plate was examined for well-isolated green colonies and the LB/amp plate was observed for white colonies with space between each other. These colonies were circled on the outside of the plates using a marker. Next, two 15 milliliter culture tubes containing 2 milliliters of nutrient growth media were obtained and labeled “+” and “-“. Using a new inoculation tube, the circled colonies from each plate were scooped out and immersed in their respective culture tubes. Once the bacteria was mixed into the solution, the tubes were sealed and placed horizontally into the 32⁰ incubator for 24 hours.

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,

Just like eukaryote species, not all bacteria species are identical in the way they behave, grow or interact with their environment (Mujtaba & DeJarnette, 2012). Microbes can be unique in the way they grow on nutrient agar (NA) plates. How their colonies form on the agar plates can also be an exclusive property of specific bacteria species. Microbes can grow in the presence of different nutrients, environments and can also be inhibited by or thrive in the presence of specific agents in the medium. For example inoculating a blood agar plate with the organism, can indicate its hemolysis activity, which it will fall in one of the three groups alpha (α), beta (β), or gamma (γ).

You can grow microorganisms in liquid media or on solid media. Most bacteria can be grown in labs as long as the media contain a source of the major nutrients; carbon, nitrogen, sulphur, and phosphorous. They may also need to have other nutrients. These nutrients are made into a broth and the pH and salinity can be adjusted. The nutrient broth is placed in test tubes, which are plugged with cotton wool, capped with foil and then sterilised in an autoclave, at 121c for 20minutes. These tubes are then cooled before they are inoculated. To prepare the streak plates we dipped an inoculating loop into ethanol then placed it in the flame until the loop glowed red. Still holding the inoculating loop by its handle we removed the lid from

The purpose of this project was to identify the identities of two unknown bacteria in a mixed broth culture by using several separation methods. To separate the organisms, a four-way streak plate technique was used to isolate the two unknown bacteria into separate visible colonies. Then after each colony were clearly isolated; the two unknowns were processed through Gram staining test to determine the Gram stain and morphology. After Gram staining, a carbohydrate test was performed on each unknown to determine if it had glucose, sucrose, or lactose fermentation. The results of the sugar test help determining which biochemical test should be performed next. The Gram positive organism was tested through a carbohydrate fermentation test, then further tested to confirm its identity through an indole and catalase test. The Gram negative organism was tested through carbohydrate fermentation test, then further tested to confirmed its identity through an indole, and TSIA test. After running four biochemical tests, the results conclude that the Gram positive unknown was Staphylococcus aureus. S. aureus was identified based on the fermentation results of the glucose test, negative indole test, and a positive catalase production. S. aureus is a Gram positive circular shaped bacterium that is very common in the U.S and is normally found in the nose, respiratory tract, and on the skin. This bacterium is usually the most common cause of infections after injury or surgery.

When reflecting back to experiment 3, Aseptic Technique and Culturing Microbes, I realized the large amount of microorganisms that can be found in everyday life. Many different types are found with in the human body. Theses experiments focused on two types of bacteria. First was Staphylococcus epidermidis, found on the skin, and second was Lactobacillus acidophilus, found in the gastrointestinal tract. Both have similar needs for growth when it comes to temperature, however, different growth environments are used.

When testing this certain type of bacteria the warm temperature caused it to grow exceptionally fast comparted to the room temperature. Bacteria are single celled microbes. The cell structure is simpler than that of other organisms as there is no nucleus or membrane

Each mixed culture that was tested had one gram positive and one gram negative bacterial species. The possible species of bacteria that could have been isolated from the mixtures included the following: Bacillus subtilis, Corynebacterium glutamicum, Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Enterobacter aerogenes, Salmonella enterica, and Pseudomonas aeruginosa. The identities of the unknown species were determined through comparing the experimental data against data acquired from earlier experimentation.

Six experiments were carried in this report concerning the effect that different environmental factors have on microbial growth. The results were recorded into tables where (+) symbolises growth and (–) symbolises no growth.