BIOCHEMINSIDER

By Prof Walter Jaoko Introduction The nitrate reduction test is a qualitative procedure for determining the ability of bacteria to reduce nitrate. In the reaction, nitrate is reduced to nitrite, which may then be further reduced to nitrogen gas or ammonia.Other uses of Nitrate Reduction Tests are:  Differentiating Mycobacterium species. Identifying species of Neisseria and separating them from Moraxella and Kingella species. The nitrate … Read more

By Prof Walter Jaoko Introduction Acid-Fast (AF) is an important special staining technique used in the histology laboratory. It is a differential staining techniques which was first developed by Ziehl and later on modified by Neelsen 1883. This method is used for those microorganisms which are not staining by simple or Gram staining method, particularly the member of … Read more

By Prof Walter Jaoko Introduction DNA hydrolysis test or Deoxyribonuclease (DNase) test is used to determine the ability of an organism to hydrolyze DNA and utilize it as a source of carbon and energy for growth. In this regard, Deoxyribonuclease test medium (DNase agar) prepared according to the formula of Jeffries, Holtman and Guse, is … Read more

By Prof Walter Jaoko Introduction Oxidase test is most helpful in screening colonies suspected of being one of the Enterobacteriaceae (all negative) and in identifying colonies suspected of belonging to other genera such as Aeromonas, Pseudomonas, Neisseria, Campylobacter, and Pasteurella (positive). Oxidase test uses disks impregnated with a reagent such as N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) or N,N-dimethyl-p-phenylenediamine (DMPD), which is also a redox indicator. The reagent is a dark-blue … Read more

By Prof Walter Jaoko Objectives To determine the ability of the organism to hydrolyse lipid. To identify bacteria capable of producing the exoenzyme lipase. Principle Lipids generally are nonpolar molecules that do not dissolve well in water.  Fats are one type of lipids that are large polymers of fatty acids and glycerol that are too … Read more

By Prof Jeremiah Seni Introduction The Catalase test is used to differentiate staphylococci (catalase-positive) from streptococci (catalase-negative). The enzyme catalase, is produced by bacteria that respire using oxygen and protects them from the toxic by-product of oxygen metabolism. Catalase-positive bacteria include strict aerobes as well as facultative anaerobes, although they all have ability to respire … Read more

By Prof Jeremiah Seni What Is MacConkey Agar? MacConkey agar (MAC) was developed as the first solid differential media in the 20th century by a bacteriologist, Alfred Theodore MacConkey. While working for the Royal Commission on Sewage Disposal, His role was to inspect drinking water sources for the presence of Gram-negative enteric organisms. Which usually inhabit … Read more

By Prof Jeremiah Seni Objective To detect the ability of organisms to produce citrase enzyme.The citrate test detects the ability of an organism to use citrate as the sole source of carbon and energy. Principle Bacteria are inoculated on a medium containing sodium citrate and a pH indicator such as bromothymol blue. The medium also contains inorganic ammonium salts, which are utilized as sole … Read more

By Prof Daniel Asrat Introduction The objective of Hydrogen Sulphide Test is to determine whether the microbe reduces sulfur-containing compounds to sulfides to produce hydrogen sulfide gas.Some bacteria have the ability to reduce sulphur to hydrogen sulphide. It is a colorless gas, which reacts with iron (ferrous salts) to produce black precipitates of ferrous sulphide.It also reacts with lead … Read more