Biochemical tests are laboratory procedures that use specific chemical reactions to identify and characterize microorganisms, such as bacteria. These tests are often used to identify the presence of specific enzymes or metabolic pathways in a microorganism, which can help to distinguish it from other microorganisms.
Some common biochemical tests used in bacteriology include:
These are just a few examples of the many different biochemical tests that are used in bacteriology. Biochemical tests can be useful for identifying and classifying bacteria, and for understanding their metabolism and ecological role.
What is a Glucose Tolerance Test? A glucose tolerance test is a test that is used to diagnose diabetes or prediabetes. It involves measuring the body’s ability to process glucose, a type of sugar that is the main source of energy for the body. During the test, a person will drink a solution containing a … Read more
After wastewater treatment, the chemical oxygen demand (COD) is used to determine the amount of contamination in the water. The higher value of chemical oxygen demand implies that the water sample has a greater amount of organic pollutants. The COD test measures only substances that can be chemically digested. The determination of COD requires less … Read more
All aquatic organisms depend on the oxygen in the water (dissolved oxygen) for survival. As a food supply, aquatic microbes consume the organic matter discharged into the water. Plant decomposition and leaf fall are common sources of organic debris. Using the dissolved oxygen in the water, bacteria will decompose this organic stuff and form less … Read more
What is Presence/Absence Test? The availability of potable water for bathing, drinking, and cooking is essential for modern society. Diseases such as diarrhoea, typhoid, cholera, etc., can be transferred by feces-contaminated water and other sources. Different methodologies for bacteriological water testing have been developed. Weiss and Hunter presented a streamlined method for bacteriological testing of … Read more
The main sources of fructose in the diet are the disaccharide sucrose (cane sugar) and high fructose corn syrups (HFCS) found in processed foods and drinks. It is also found in free form in honey and many fruits. Insulin does not control how much fructose gets into the cells in the body. Glucose, on the … Read more
The Gram stain is typically the initial step in identifying bacteria and frequently dictates future identification methods. Misclassification may come from the tendency of some gram-positive rods to seem gram-variable or gram-negative, particularly members of the genera Bacillus, Erysipelothrix, Lactobacillus, and Listeria. In 1976, Cerney reported employing L-alanine-4-nitroanilide to identify cell-wall aminopeptidase, which was connected … Read more
Test Name Esculin Hydrolysis test Purpose This test is used to try to figure out what kind of Enterobacteriaceae it is and how it differs from other kinds.To see if the microbe can use esculin as a source of carbon by breaking it down with water. Media Required Esculin Hydrolysis Agar Result Positive: Blackened medium, … Read more
Current nitrite reduction tests are based on Peter Griess’s 1858 description of the Griess diazotization reaction. Peter Griess, the son of a blacksmith, was raised on a farm in Prussia, but “…tilling the soil was not to his liking, and his father often discovered him in a corner of the field, engrossed in a book … Read more
In 1875, Reoch theorised that microorganisms were responsible for the alkaline fermentation of urine (urea) and the subsequent formation of ammonia. Subsequently, numerous types of urea-degrading bacteria were isolated and their urease activity was examined. Urease activity is a crucial criterion for the identification of Proteus species and permits Proteus to be separated from non-lactose-fermenting … Read more
The Pyrrolidonyl Arylamidase (PYR) test is a fast test used to identify group A beta-hemolytic streptococci and enterococci. Escherichia coli (-ve) is also identified using the PYR test, which distinguishes it from other indole-positive, lactose-positive, Gram-negative rods. It is also known as PYR (L-pyrrolidonyl—naphthylamide) and serves as a substrate for pyrrolidonyl peptidase detection. L-Pyrrolidonyl- -naphthylamide … Read more
The Hippurate Hydrolysis Test measures an organism’s ability to create hippuricase, an enzyme that hydrolyzes the substrate hippurate. It identifies Streptococcus agalactiae, Campylobacter jejuni, Listeria monocytogenes, and Gardnerella vaginalis. The final products of hippuric acid hydrolysis by hippuricase are glycine and benzoic acid. The oxidising agent ninhydrin deaminates glycine and is reduced in the process. … Read more
Kligler Iron Agar is a combination of Kligler’s lead acetate medium and Russels Double Sugar Agar, and it is used to differentiate typhoid, dysentery, and related bacilli. Bailey and Lacey replaced the andrade indicator formerly used as pH indicator with phenol red. Kligler Iron Agar distinguishes between lactose fermenters and nonfermenters. It separates Salmonella Typhi … Read more
What is Triple Sugar Iron Test (TSIA Test)? Purpose of Triple Sugar Iron Agar test (TSIA Test) The Triple Sugar Iron (TSI) Agar test, meticulously designed as a differential medium in tubed format, plays an instrumental role in microbiological diagnostics. Its primary objectives are multifaceted, as delineated below: In summation, the Triple Sugar Iron (TSI) … Read more
What is Hydrogen Sulfide (H2S) Test? This test determines whether sulfur-containing chemicals are converted to sulphides during the microbe’s metabolic activity. When sulphide is generated, it reacts with iron compounds to form FeS, a black precipitate. Multiple iron-containing media permit the detection of hydrogen sulphide generation. Sulfide-Indole-Mobility (SIM) medium is utilised. This nutrient medium enables … Read more
What is Nitrate Reduction Test? Nitrate reduction test is used to differentiate Enterobacteriaceae based on their ability to produce nitrate reductase enzyme, which hydrolyzes nitrate (NO3–) to nitrite (NO2–), which may be further degraded to various nitrogen products such as nitrogen oxide, nitrous oxide, and ammonia (NH3), depending on the organism’s enzyme system and the … Read more
What is the Litmus Milk Test? Litmus Milk Medium is a liquid medium suggested for use in qualitative tests for determining the activity of bacteria on milk and maintaining lactic acid bacteria. The Litmus Milk Test requires a litmus milk medium, which is a liquid medium that differentiates bacteria based on numerous metabolic events in … Read more
What is API (Analytical Profile Index) 20E Test? Principle of APT Test for Bacteria API 20E Test Kit API 20E is a specialized kit designed for bacterial identification, consisting of 20 distinct tests. These tests aid in characterizing various metabolic activities and enzymatic reactions of the organisms being examined. Each test provides valuable information to … Read more
Test Name Acetamide utilization Test Purpose Differentiate microorganisms according to their capacity to utilise acetamide as their only carbon source. Microorganisms Tested Isolated colonies of Gram-negative, non-glucose-fermenting rods that emit a luminous pigment and are suggestive of P. aeruginosa. Result Positive: The slant shows growth, and its colour changes from green to intense blue.Negative: There … Read more
Test Name Acetate Utilization Test Detection Differentiate species based on ability to utilise acetate as the sole source of carbon. Typically used to distinguish Shigella spp. from Escherichia coli. Test organism It is best to use an acetate utilisation test to tell Shigella spp. from Escherichia coli. Test isolates are Gram-negative rods that don’t ferment … Read more
Overview of Butyrate Test Test Name Butyrate Disk Test Detection Enzyme butyrate esterase Uses This is a quick way to find out if Moraxella catarrhalis has the enzyme butyrate esterase. Result A blue colour development Require Bromochloro-indolyl butyrate and 4-methylumbelliferyl impregnated discs Test Organism Moraxella catarrhalis ATCC 25240: butyrate positive Butyrate Disk is a reagent-coated … Read more
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