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 …show more content…
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
After 48 hours of incubation the agar plates were viewed. Individual colonies were tested for successful isolation by gram staining and then viewing the stained bacteria under a microscope. Isolation was successful. One colony of each unknown bacteria was transferred to an agar slant for growth. The agar slants were stored at room temperature over the weekend so that they would not grow too much.
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
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
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.
Introduction The main purpose of accomplishing multiple tests on an unknown organism was to pick a random unknown tube and identify which microorganism it was. One of the important things about these different tests is to make sure the tests are performed correctly and the results are interpreted correctly or else the unknown organism will come out as a mess. One instance where it is important to interpret the tests is in the medical field. If a patient is sick because of an unknown organism, samples from the patient can be taken out and the lab can perform tests on it and interpret the results correctly to identify the exact type of microorganism in order to treat the patient with antibiotics and treatment. In the end, this will help scientists cure diseases, help make treatments for specific organisms, and help the world be a healthier place one step at a time.
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.
To further determine the species of the unknown bacteria, an API 20E was used. API 20E system utilized a plastic strip with 20 separate compartments with each compartment consisting of cupule or a depression and a small tube containing a specific dehydrated medium (1). The ONPG tube consisted of an ingredient that functioned as an internal indicator. The ADH, LDC, ODC and URE tubes contain phenol red as the indicator. The CIT, GLU, MAN, INO, SOR, RHA, SAC, MEL, AMY and ARA tubes contain bromthymol blue as an indicator. The GEL tube contains charcoal and the H2S tube contains iron salts as indicators. The TDA, IND and VP tubes contain no indicator. All the tubes contain buffers and all the tubes with the exception of the CIT and URE contain
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.
For bacteria to be utilised to its full potential and to meet the demands of quantity need for the production of foods and medicines it is key that experts are able to firstly distinguish what type bacteria is need for a certain production and secondly, and very importantly, how to reproduce that bacteria to create enough of it needed for mass production of a certain product.
There were three bacteria that were studied during this experiment. Staphylococcus is a type of bacteria that is often found on the body of human beings and animals. It is found on the skin and hair as well as in the noses and throats. Staphylococcus can cause food poisoning when it is exposed to food and contaminated because the food is not properly refrigerated. (Food Safety) These bacteria are Gram-positive with a spherical shape that often group into clusters, much like grapes. (Bacteriology) The only way to kill these bacteria is by cooking and pasteurization. Bacillus cereus is a type of bacteria that produces toxins that can cause two types of illnesses. One type causes diarrhea and the other causes nausea and vomiting. These bacteria are found in foods and multiple rapidly at room temperature. (Food Safety) Bacillus cereus is also Gram-positive and is rod-shaped and very large. It can spread easily to many types of foods such as plants, eggs, meats, and dairy products. (MicrobeWiki) Escherichia coli is bacteria found in the gastrointestinal tract and are able to produce a toxin that can produce serious infections. This bacterium can be acquired by consuming contaminated food or water. (European Centre) E. coli is often used to help your body break down and digest certain foods. It becomes dangerous when the bacteria go from the intestines into the blood. (Kids Health) Escherichia coli, unlike any other bacteria that was studied, is Gram-negative. It is also rod shaped and is about average size. (Mansfield)
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.