Bios242 Lab2 Essay

Depending on what a bacteria can and cannot do, will help to correctly identify it. It is always important to start out with a purity check. To achieve that, you can inoculate an agar plate and incubate for 48 hours. Make sure you only see one type of colonies on the plate. Knowing the optimal temperature for the bacteria will also let a scientist know where to place the different types of medias he/she inoculates with the unknown bacteria. Knowing if you are working with a gram positive or gram negative bacterium, a scientist will need to perform a gram stain. This will also help to see the shape and arrangement of the bacteria. The size can be determined by doing a simple stain. The size of most bacteria ranges from .5- 10um. This specific bacteria that I was working with, was smaller than 2um. Most bacteria can grow with the presence of oxygen. A simple test like the gas pack can be performed to figure out if growth is possible without oxygen is doable. My unknown bacteria needs oxygen to grow. Throughout my study, the unknown bacteria was tested to see if it can grow in acidic conditions, however no growth occurred. Before inoculation, the substrate was a clear yellow color and in liquid state. After receiving the negative result, I kept the broth in the 37C incubator for 7 more days to confirm the negative result. Using premade slants with different types of sugars such as Mannitol, Sorbitol, Lactose, Trehalose, Maltose and Sucrose, to determine if the bacteria can metabolize glucose and if the bacteria is oxidative or fermentative. It was determined that my bacteria is strictly oxidative (needs oxygen to grow) and cannot metabolize glucose. Another test was done to confirm if the bacteria was able to utilize different carbohydrates in the presence of oxygen. I used Cellobiose, Arabinose, Adonitol, Fructose and Malonate wee tabs. Out of the 5 different types of carbohydrates, only 3 different

The objective of these “unknown” experiments was to take a mixed culture, which contains two unknown species, and identify those species through a series of tests. The group was informed that one species of bacteria would be a gram-negative bacillus and the other would be a gram positive coccus. The tests to be conducted ranged from streak plate isolation to biochemical tests. Each test to be conducted was discussed and agreed upon by all group members. The results of each test were analyzed by the group and led to selection of the next test that would further narrow the possible identity of the unknown species.

The first test executed was the fermentation of carbohydrates. The objective of this particular test is to identify the ability of microorganisms to ferment a specific carbohydrate (Reiner, 2012). The test can be used to identify three different ways in which bacteria can ferment simple carbohydrates. Bacteria can be tested for acidity, alkalinity, whether or not it remains neutral and gas formation (Reiner, 2012). To conduct the carbohydrate fermentation test, a pH indicator, bromocresol purple, is used to indicate an acidic characteristic (Reiner, 2012). Bromocrescol purple indicates carbohydrate fermentation media by turning a deep purple if it’s an uninoculated media, yellow if it’s acidic and purple if it’s alkaline (Reiner, 2012). Durham tubes are placed inside the tubes containing the media and bacteria to detect gas production (Reiner, 2012). Three different carbohydrates were tested for fermentation during this test: glucose, sucrose and lactose for each of the

A pH indicator in the medium changes color to indicate acid production. Phenol red is red at neutral pH but turns yellow at 6.8 or lower, indicating fermentation which is a positive result. If it stays red or turns magenta or hot pink, that indicates that the pH level has risen and it is negative.

The aim of this experiment was to separate standard mixtures of monosaccharides. Thin-layer chromatography was used to detect monosaccharides in urine samples taken from patients suffering from disorders of carbohydrate metabolism.

When the household substances were added to the red cabbage indicator they changed colour, which helped determine the pH levels. There were many different colours which indicated a variety of pH levels. The different colours also helped me categories them into the three categories known as acid, base and neutral.

There are four main classes of macromolecules: carbohydrates, lipids, proteins and nucleic acids. For this experiment the main focus will go to the carbohydrates, more specifically the polysaccharides. Polysaccharides consist of three or more sugar molecules linked together (“macromolecules”) or one sugar derivative are called homopolysaccharides.(“polysaccharides” 1) Homopolysaccharides are glucose that includes glycogen and starch, which is the storage of carbohydrates in animals and plants.(“polysaccharides” 2) During the second lab of this course, one of the technique to determine if something had polysaccharides in it was using the Iodine test. Starch and glycogen units have a unique geometry that is different from cellulose and chitin which have β 1,4 bonds. (“macromolecules”) The specific geometry of the link in starch and glycogen causes a

This test checked for the enzyme called urease, which breaks urea down into ammonium and carbon dioxide. The ammonium will increase the pH. The medium has a pH indicator called phenol red. When pH goes up, it will turn a pretty bright pink (positive).

From this lab experiment, I can conclude that the red cabbage solution is an effective indicator for the acidic, basic and neutral chemical compounds. I learned that the universal indicator is also a good solution for the three types of compounds. The colours are different depending on what substance you are testing. The colours that we discovered in the pH scale are pink, red or orange. As for bases the colour was either light or dark green sometimes yellow. The colours for neutral, were violet or purple.In real life we are exposed to acids and bases everyday. For example, citric acid is in lots of citrus foods such as lemons, oranges and grapefruits. It is also added to foods for flavouring, non perishable, and cleaning supply. Citric acid creates a taste that is sweet and sour.

The next test I had to do was Phenol Red Broth Test to determine their fermentation characteristics. I only did Lactose and Sucrose. The test was done by adding carbohydrate and use phenol red as pH indicator. Acid production from fermentation of the carbohydrate will lower the pH below the neutral rang and turn the medium yellow, and Durham tube is added to indicate if there was any gas production.

In category IV, agar plates were used containing differential and selective aspects to determine the unknown bacterium. The first media test was the EMB. EMB separates fecal coliforms that are produced through carbohydrates that are fermentable, such as sucrose and lactose. The different fecal coliforms represent the differential factor of this test, while the selective factor selects against gram positive organisms. Lactose fermenters appear purple, pink, blue, and black colonies, while non-lactose fermenters appear clear to light orange. This occurs because Eosin Y and methylene indicators react at low pH forming the purple precipitate. On the other hand, vigorous fermenters appear metallic green indicate either coliform production or lactose

Fermentation occurs in the presence of carbohydrates, and the experiment was conducted to determine which carbohydrate, either glucose, fructose, sucrose, sucralose, or starch, produces the most carbon dioxide gas as a byproduct of fermentation. Respirometers are devices that measure the rate of aerobic or anaerobic respiration of organisms or foods through the measurement of certain gasses, such as carbon dioxide ("Respirometers Information," n.d.). Respirometers show the rate of anaerobic respiration, such as fermentation, through the measurement of the production of carbon dioxide

After multiple differential tests, it was concluded that unknown #20 was Citrobacter freundii. After conducting the Gram stain to ascertain that the unknown bacterium was a Gram negative bacilli, the species were inoculated in multiple biochemical tests. The tests that led to the conclusion of a Gram Negative bacteria were Oxidase, lactose fermentation, MR, VP, Indole, and H2S production. For the oxidase test, there were two categories one was for positive and negative results of the test. The positive result had three different types of bacteria while the negative result was the Enterobacteriaceae family. If the result of the test was positive, then there would have been color reaction. However after the test was performed in the oxidase test it showed no color reaction which indicates that the test was negative fitting the Enterobacteriaceae classification. Following was lactose fermentation test to analyze if the bacterium was capable of fermenting sugar. If the test was negative the tube was stayed the phenol red and no gas would have been collected by the Durham tube. However, after being incubated with bacteria, it was observed that the phenol red turned yellow and gas was collected in the inverted tube, signifying the bacteria grew. The changing of the color demonstrated that the pH dropped and that the bacteria is able to ferment sugar. Due to the positive result of the test therefore it narrowed down to a small amount of bacteria. To further narrow the list of

The Citrate Test indicates whether or not the bacteria contain the enzyme citrate permease, which is needed to bring citrate into the cell. The media used contains the pH indicator bromothymol blue which is green at a neutral pH level and blue at alkaline pH levels. If the top of the citrate slant has turned from green to blue, the culture is positive for citrate degradation producing alkaline byproducts. If not, the results are negative.

Extensive research has shown that a starch with a higher carbohydrate concentration produces more glucose as there are more glycosidic bonds to hydrolyse,