Introduction
In this lab project, the microbiology students were given 2 unknown bacteria in a mixed broth each broth being numbered. The goal of this project is to determine the species of bacteria in the broth. They had to separate and isolate the bacteria from the mixed broth and ran numerous tests to identify the unknown bacteria. The significance of identifying an unknown bacteria is in a clinical setting. Determining the exact bacteria in order to prescribe the right treatment for the patient. This project is significant for a microbiology students because it gives necessary skills to them for future careers relating to clinical and research work.
Materials and Methods
Streak plate technique was used to isolate pure culture for each bacteria (2). The Gram stain was used to determine Gram reaction and morphology of each bacteria (2) Selective and differential media such as, salt agar, MacConkey agar and blood agar were used for bacterial identification (2). Gelatin deeps were inoculated to detect production of gelatinase (2). Starch Agar plate were inoculated to detect amylase (2). Ocular reticle used to determine bacteria size (2). Motility deeps were inoculated to detect motility on bacteria (2). Thioglycollate broth used to determine oxygen requirements (2). Carbohydrate fermentation
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was determined using glucose broth, lactose broth, mannitol broth, and MR-VP broth (2). Lysine broth and ornithine broth used to detect decarboxylase (2). Phenylalanine agar used to detect deaminase (2). Kovacs’ oxidase reagent was used to detect cytochrome oxidase (2). Hydrogen peroxide was used to detect catalase (2). Urea broth was inoculated to detect urease (2). Tryptone broth was inoculated to detect indole production (2). Simmon’s citrate slant inoculated to detect growth on citrate (2). Peptone iron agar deep inoculated to detect hydrogen sulfide production (2). DNase agar plate inoculated to detect deoxyribonuclease activity (2). Nitrate broth inoculated to detect nitrate reductase and nitrite reductase (2). RapID multi-test was conducted for identification of the bacteria (2). Thawed plasma was inoculated to detect coagulase (2). Results The two unknown bacteria’s Gram reaction given is both Gram positive and Gram negative.
The Gram positive bacteria has been nicknamed Posi. The Gram positive species’ morphology includes having an opaque opacity with a smooth margin. The moisture content of the Gram positive species is shiny and the pigmentation is gold. The Gram positive species grows at an optimal temperature of 37°C. The shape of the Gram positive species is a cocci, with an arrangement of grapelike clusters. The Gram positive species’ size ranges from .5-1.5 µm. Oxygen requirement of the Gram positive species is facultative, and has complete lysis of red blood cells. All results are summarized in Table
1. The Gram negative species has been nicknamed Negi. The Gram negative species’ morphology includes having a translucent opacity with a filamentous margin. The moisture content of the Gram negative species is shiny and the pigmentation is clear but with a yellowish hue. The Gram negative species grows at an optimal temperature of 37°C. The shape of the Gram negative species is a rod, with an arrangement of groups of single or multiple bacteria clumped together. The Gram negative species’ size ranges from 1.5-2.5 µm. Oxygen requirement of the Gram negative is facultative, and catalase reaction was weak. All results summarized in Table 1.
I identified the genus and species of an unknown bacterial culture, #16, and I applied the following knowledge of morphologic, cultural and metabolic characteristics of the unknown microorganism according to the laboratory manual as well as my class notes and power point print outs. I was given an incubated agar slant labeled #16 and a rack of different tests to either examine or perform myself; the tests are as follows: Gram Stain; Nutrient Gelatin Test; Carbohydrate Fermentation; Dextrose, Lactose and Sucrose; IMVIC tests; Citrate, Indole, Mythel-Red and Vogues Proskauer test; as well as a Urease and TSI Test.
The purpose of the Unknown White Compound Lab was to identify the unknown compound by performing several experiments. Conducting a solubility test, flame test, pH paper test, ion test, pH probe test, conductivity probe test, and synthesizing the compound will accurately identified the unknown compound. In order to narrow down the possible compounds, the solubility test was used to determine that the compound was soluble in water. Next, the flame test was used to compare the unknown compound to other known compounds such as potassium chloride, sodium chloride, and calcium carbonate. The flame test concluded that the cation in the unknown compound was potassium. Following, pH paper was used to determine the compound to be neutral and slightly
The unknown bacterium that was handed out by the professor labeled “E19” was an irregular and raised shaped bacteria with a smooth texture and it had a white creamy color. The slant growth pattern was filiform and there was a turbid growth in the broth. After all the tests were complete and the results were compared the unknown bacterium was defined as Shigella sonnei. The results that narrowed it down the most were the gram stain, the lactose fermentation test, the citrate utilization test and the indole test. The results for each of the tests performed are listed in Table 1.1 below.
Forensic Science Introduction: Someone in a restaurant has suddenly fallen ill and a mystery powder has been discovered with the victim. As the chief investigator, your duty is to identify the mystery substance through a lab. In this lab, it will consist of five known compounds and one unknown compound. Your job is to distinguish which one out of the five substances is the mystery powder. To figure out the mystery matter you will have to compare their physical and chemical properties and match them with the appropriate compound.
The first day an unknown sample was assigned to each group of students. The first test applied was a gram stain to test for gram positive or gram-negative bacteria. The morphology of the two types of bacteria was viewed under the microscope and recorded. Then the sample was put on agar plates using the quadrant streak method for isolation. There were three agar plates; one was incubated at room temperature, the second at 30 degrees Celsius, and the third at 37 degrees Celsius. By placing each plate at a different temperature optimal growth temperature can be predicted for both species of bacteria.
The purpose of this study is to identify an unknown bacterium from a mixed culture, by conducting different biochemical tests. Bacteria are an integral part of our ecosystem. They can be found anywhere and identifying them becomes crucial to understanding their characteristics and their effects on other living things, especially humans. Biochemical testing helps us identify the microorganism present with great accuracy. The tests used in this experiment are rudimentary but are fundamental starting points for tests used in medical labs and helps students attain a better understanding of how tests are conducted in a real lab setting. The first step in this process is to use gram-staining technique to narrow down the unknown bacteria into one of the two big domains; gram-negative and gram-positive. Once the gram type is identified, biochemical tests are conducted to narrow down the specific bacterial species. These biochemical tests are process of elimination that relies on the bacteria’s ability to breakdown certain kinds of food sources, their respiratory abilities and other biochemical conditions found in nature.
The purpose of this laboratory is to learn about cultural, morphological, and biochemical characteristics that are used in identifying bacterial isolates. Besides identifying the unknown culture, students also gain an understanding of the process of identification and the techniques and theory behind the process. Experiments such as gram stain, negative stain, endospore and other important tests in identifying unknown bacteria are performed. Various chemical tests were done and the results were carefully determined to identify the unknown bacteria. First session of lab started of by the selection of an unknown bacterium then inoculations of 2 tryptic soy gar (TSA) slants, 1 nutrient broth (TSB), 1 nutrient gelatin deep, 1 motility
In the last decade, the number of prescriptions for antibiotics has increases. Even though, antibiotics are helpful, an excess amount of antibiotics can be dangerous. Quite often antibiotics are wrongly prescribed to cure viruses when they are meant to target bacteria. Antibiotics are a type of medicine that is prone to kill microorganisms, or bacteria. By examining the PBS documentary Hunting the Nightmare Bacteria and the article “U.S. government taps GlaxoSmithKline for New Antibiotics” by Ben Hirschler as well as a few other articles can help depict the problem that is of doctors prescribing antibiotics wrongly or excessively, which can led to becoming harmful to the body.
The first step to the unknown is selecting an actual organism. The best way to select a culture is based on a high-quality distribution. Equally important, shaking up the broth tube facilitates in the distribution. Upon selection, a gram check for purity is performed. Step by step instructions for this procedure can be found in Benson’s, Microbiological Applications p. 99. Furthermore, an aseptic technique must be performed for this test and the entire tests following the unknown. The purpose of this test is to differentiate between gram positive and gram-negative bacteria. The key indicator of gram-positive bacteria is a purple stain and a pink stain for gram-negative bacteria. A slide is viewed with a microscope under oil immersion. Equally
After that bolt the slide dry with bibulous paper. After that examine the slide under the oil immersion lens. After determining the Gram stain reaction, 18 specific biochemical tests were performed for further analysis. The way of biochemical test was different but need to incubate at 37 degree Celsius. Phenol red lactose, phenol red dextrose, phenol red sucrose, methyl red, voges-proskauer, citrate utilization test, urea hydrolysis, and nitrate reduction are the media which are in test tube as liquid. Which were use Inoculating loop to deep tube with assigned bacteria. Triple sugar iron, and citrate utilization are in slant and we use Inoculating needle to deep tube with assigned bacteria. Again, starch hydrolysis, casein hydrolysis, lipid hydrolysis, oxidase test and catalase test were test from agar plate which use inoculating loop. For those media, which were in agar plate, inoculate with loop by making a line streak down the center of the agar. After that all 18 medias need to incubate at 37 degree Celsius for 48 hours. After 48 hours, some media show bacteria’s characteristics and morphology without adding extra reagent. Some media need reagent to examine morphology and physiology. Experiment such as MRVP needs methyl red, Barritt’s A, and Barritt’s
A slide was prepared with the unknown bacteria and the Gram stain using crystal violet and safranin as the reagent, iodine as the mordant, and alcohol as the decolorizing agent. This procedure was performed to identify the gram reaction, morphology and the arrangement of the unknown bacteria. A gram negative rod with random arrangement was seen under the light microscope after the gram stain.
Introduction : in this lab we are trying to see what location makes bacteria grow faster and which one has the most . All bacteria reproduce and their DNA floats freely in cell . Eubacteria contains cell wall made of peptidoglycan, but archaebacterias cell wall isn't made of peptidoglycan. Eubacteria is found everywhere but archaebacteria is found in extreme hostile environments.
Bacterial cells, like plant cells, are surrounded by a cell wall. However, bacterial cell walls are made up of polysaccharide chains linked to amino acids, while plant cell walls are made up of cellulose, which contains no amino acids. Many bacteria secrete a slimy capsule around the outside of the cell wall. The capsule provides additional protection for the cell. Many of the bacteria that cause diseases in animals are surrounded by a capsule. The capsule prevents the white blood cells and antibodies from destroying the invading bacterium. Inside the capsule and the cell wall is the cell membrane. In aerobic bacteria, the reactions of cellular respiration take place on fingerlike infoldings of the cell membrane. Ribosomes are scattered throughout the cytoplasm, and the DNA is generally found in the center of the cell. Many bacilli and spirilla have flagella, which are used for locomotion in water. A few types of bacteria that lack flagella move by gliding on a surface. However, the mechanism of this gliding motion is unknown. Most bacteria are aerobic, they require free oxygen to carry on cellular respiration. Some bacteria, called facultatibe anaerobes can live in either the presence or absence of free oxygen. They obtain energy either by aerobic respiration when oxygen is present or by fermentation when oxygen is absent. Still other bacteria cannot live in the presence of oxygen. These are called obligate anaerobes. Such bacteria obtain energy only fermentation. Through fermentation, different groups of bacteria produce a wide variety of organic compounds. Besides ethyl alcohol and lactic acid, bacterial fermentation can produce acetic acid, acetone, butyl alcohol, glycol, butyric acid, propionic acid, and methane, the main component of natural gas. Most bacteria are heterotrophic bacteria are either saprophytes or parasites. Saprophytes feed on the remains of dead plants and animals, and ordinarily do not cause disease. They release digestive enzymes onto the organic matter. The enzymes breakdown the large food molecules into smaller molecules, which are absorbed by the bacterial cells. Parasites live on or in living organisms, and may cause disease. A few types of bacteria are Autotrophic, they can synthesize the organic nutrients they require from inorganic substances. Autotrophic bacteria are either photosynthetic or Chemosynthetic. The photosynthetic bacteria contain chlorophyll that are different from the plant chlorophyll. In bacterial photosynthesis, hydrogen is obtained by the splitting of compounds other than water.
The identification of the bacterial unknown was determined through a series of tests using differential media and a gram stain. These tests revealed information about the motility, the metabolism, and the enzymes of the unknown microorganism. The most basic technique for all tests is called the aseptic technique. This technique is “to prevent contamination of the sample” (Leboffe and Pierce, 2010). This is the first technique taught to students in the lab. Aseptic transfers were done with either an inoculating loop or needle between the stock of microorganisms to a sterile media. Sterile media included tryptic soy broth or tryptic soy agar. To prevent contamination, inoculating loops and needles are usually sterilized in the Bunsen burner flame, but in lab, a micro-incinerator was used instead. Other measures taken to avoid contamination include holding an open test tube at an angle and heating the tube’s lip and surrounding air (Leboffe and Pierce, 2010).
Isolation of bacteria includes several techniques by which different bacterial colonies from a mixed culture can be separated. This isolation is important as it helps in studying the particular organism with its distinguished traits. Bacteria are in habit of living in an association with other organism/bacteria as this association will help in the better survival of an organism. These microbial populations will cooperate together and achieve better nutrients for each other because the waste of one may serve as a nutrient for the other. Similarly the waste from the metabolism of the one may provide the favourable condition to the other for growth.