Some Metabolic Activities of Bacteria


Diagnostic Microbiology In Action
  Principles of Diagnostic Microbiology
    Primary Media for Isolation of Microorganisms
    Some Metabolic Activities of Bacteria
      Simple Carbohydrate Fermentations
      Starch Hydrolysis
      Production of Indole and Hydrogen Sulfide, and Motility
    Activities of Bacterial Enzymes
      The Activity of Urease
      The Activity of Catalase
      The Activity of Gelatinase
      The Activity of Deoxyribonuclease (Dnase)
      The Activity of a Deaminase
    Principles of Antigen Detection and Nucleic Acid Assays for Detection Identification of Microorganisms
      Antigen Detection Assays
      Enzyme Immunoassay (Eia)
      Nucleic Acid Detection Assays

Microbial metabolic processes are complex, but they permit the microbiologist to distinguish among microorganisms grown in culture. Bacteria, especially, are identified by inoculating pure, isolated colonies into media that contain one or more specific biochemicals. The biochemical reactions that take place in the culture can then be determined by relatively simple indicator reagents, included in the medium or added to the culture later.

Some bacteria ferment simple carbohydrates, producing acidic, alcoholic, or gaseous end products. Many different species are distinguished on the basis of the carbohydrates they do or do not attack, as well as by the nature of end products formed during fermentation. Still others break down more complex carbohydrates, such as starch. The nature of products formed in amino acid metabolism also provides information as to the identification of bacterial species. The production of visible pigments distinguishes certain types of bacteria.

Working with pure cultures freshly isolated from clinical specimens, the microbiologist uses a carefully selected battery of special media to identify their characteristic biochemical properties.