What are the biochemical test for bacteria identification?

Each species of bacteria has specific metabolic needs and relies on different enzymes to fuel those unique needs. The presence of catalase, gelatinase, oxidase, urease, for example, can be used to identify the species of bacteria. Biochemical reactions used in biochemical tests depend on the presence of such bacteria.

What are the biochemical test for gram negative bacteria?

The basic tests used are catalase, oxidase, indole, citrate, urease, and phenylalanine. With this scheme, 12 genera and 23 species can be identified using these limited biochemicals which are within the reach of most of the microbiology laboratories having limited resources.

What is a lab test to identify bacteria?

A bacteria culture test can help find harmful bacteria in your body. During a bacteria culture test, a sample will be taken from your blood, urine, skin, or other part of your body. The type of sample depends on the location of the suspected infection.

What are 3 tests we could use to identify an unknown bacteria?

Begin the process of identifying unknown bacteria by observing their physical characteristics, such as cell wall, shape and linkages. Use standard laboratory procedures, like cell staining, culturing and DNA sequencing to further narrow down your identification.

What does the MR VP test determine?

This test is used to determine which fermentation pathway is used to utilize glucose. In the mixed acid fermentation pathway, glucose is fermented and produces several organic acids (lactic, acetic, succinic, and formic acids).

Which biochemical test can be used for the rapid identification of E coli?

spot indole test coli strains that are indole positive, the spot indole test has been used for the rapid, presumptive identification of E. coli.

What does a MacConkey agar test for?

MacConkey agar is a selective and differential culture medium for bacteria. It is designed to selectively isolate Gram-negative and enteric (normally found in the intestinal tract) bacteria and differentiate them based on lactose fermentation.

What tests are in biochemistry?

Lab Test

Is Gram stain biochemical test?

This staining technique provides information about cell wall structure as Gram-positive organisms have only a grid of peptidoglycan and Gram-negative cells posses an additional lipid bilayer. … The Gram Stain remains important for identification of bacteria, and forms the basis for the selection for biochemical tests.

What are two methods of identifying bacteria?

Modern Methods for Identifying Microbes

Why biochemical test are conducted?

Biochemical tests are among the most important methods for microbial identification. … Microbial biochemistry tests shorten the time required to identify microbes, reduce costs, and ensure or enhance the accuracy of identification of an unknown sample. It is the fastest developing trend in microbial identification.

What is catalase test?

The catalase test tests for the presence of catalase, an enzyme that breaks down the harmful substance hydrogen peroxide into water and oxygen. If an organism can produce catalase, it will produce bubbles of oxygen when hydrogen peroxide is added to it. … Bubbles are a positive result for the presence of catalase.

What is biochemical test microbiology?

Biochemical tests are the tests used for the identification of bacteria species based on the differences in the biochemical activities of different bacteria. Bacterial physiology differs from one type of organism to another.

How do laboratories identify unknown bacteria?

Identification of unknown bacteria is an integral module in most introductory Microbiology laboratory courses. This laboratory activity typically involves identifying bacteria based on Gram staining for morphology and gram reaction followed by studying their biochemical characteristics.

Which of the following are methods used to identify bacteria?

When identifying bacteria in the laboratory, the following characteristics are used: Gram staining, shape, presence of a capsule, bonding tendency, motility, respiration, growth medium, and whether it is intra- or extracellular.

What indicates a positive methyl red test?

Interpretation. MR: If the tube turns red, the test is positive for mixed acid fermentation (one or more organic acids formed during the fermentation of glucose).

What is the purpose of citrate utilization test?

Citrate utilization is a metabolic test used to determine an organism’s ability to utilize citrate as its lone source of carbon. Simmons citrate agar is a synthetic medium containing citrate, ammonium ions, and the pH indicator bromthymol blue. This indicator is green below pH 7.6 and blue above pH 7.6.

What is phenol red test?

Phenol Red Broth is a general-purpose differential test medium typically used to differentiate gram negative enteric bacteria. It contains peptone, phenol red (a pH indicator), a Durham tube, and one carbohydrate. … Phenol red is a pH indicator which turns yellow below a pH of 6.8 and fuchsia above a pH of 7.4.

Is Enterobacter aerogenes indole positive?

E.coli is indole-positive; Enterobacter aerogenes is indole- negative. Glucose is the major substrate oxidized by enteric bacteria for energy production.

What is the positive result for indole test?

A positive result is shown by the presence of a red or red-violet color in the surface alcohol layer of the broth. A negative result appears yellow. A variable result can also occur, showing an orange color as a result.

How do you perform a citrate test?

Procedure of Citrate Utilization Test

  1. Streak the slant back and forth with a light inoculum picked from the center of a well-isolated colony.
  2. Incubate aerobically at 35 to 37 C for up to 4-7 days.
  3. Observe a color change from green to blue along the slant.

Does Micrococcus luteus grow on MacConkey Agar?

MacConkey Agar (MAC) is a selective and differential medium designed to isolate and differentiate enterics based on their ability to ferment lactose. … Klebsiella pneumoniae ferments lactose and produces pink colonies on MAC. Micrococcus luteus does not grow in the presence of bile salts and crystal violet.

Is EMB Agar selective or differential?

Eosin methylene blue agar (EMB) is a selective and differential medium used to isolate fecal coliforms. Eosin Y and methylene blue are pH indicator dyes which combine to form a dark purple precipitate at low pH; they also serve to inhibit the growth of most Gram positive organisms.

Does Micrococcus luteus grow on EMB agar?

This microbe is coccus shaped and forms in tetrads. The colony forms as a yellow, shiny round blob. … The EMB agar showed no growth or change in color, also indicating the microbe was gram positive and a non-fermenter.

What is clinical biochemical tests?

Clinical Biochemistry is the division of laboratory medicine that deals with the measurement of chemicals (both natural and unnatural) in blood, urine and other body fluids. These test results are useful for detecting health problems, determining prognosis and guiding the therapy of a patient.

What are hematology lab tests?

Hematology tests include tests on the blood, blood proteins and blood-producing organs. These tests can evaluate a variety of blood conditions including infection, anemia, inflammation, hemophilia, blood-clotting disorders, leukemia and the body’s response to chemotherapy treatments.

What are the different tests used to differentiate Staphylococcus spp from Streptococcus spp?

Staphylococcus and Micrococcus spp. are catalase positive, whereas Streptococcus and Enterococcus spp. are catalase negative. If a Gram-positive cocci is catalase positive and presumed to be a staphylococci, the coagulase test is often performed.

Why is E coli negative for citrate test?

Only bacteria that can utilize citrate as the sole carbon and energy source will be able to grow on the Simmons citrate medium, thus a citrate-negative test culture will be virtually indistinguishable from an uninoculated slant. E. coli is citrate negative.

How do you identify a Gram-positive bacteria?

Under a microscope, gram-positive bacteria appear purple-blue because their thick peptidoglycan membrane can hold the dye. The bacteria is called gram-positive due to the positive result. Gram-negative bacteria stain pink-red. Their peptidoglycan layer is thinner, so it doesn’t retain the blue color.