Flash Plugin needed

That is, an organism is the totality of its enzymes, so by determining which enzymes are present in an unknown organism one can describe & identify that organism. In identification of microbes by biochemical tests, you will test several bacteria for the presence of a variety of enzymes.Enzymes are detected by virtue of the chemical reaction they carry out.

However, it is necessary to have a means of measuring or "seeing" an enzyme's chemical reaction. One common measuring technique involves the formation of a colored chemical as a direct result of an enzyme's activity. There are chemicals (pH indicators) that respond to the hydrogen Ion (H+) concentration by changing color. Thus if an enzymatic reaction produces acids, which increases the H+ concentration, pH-indicators respond by changing color as the acidity changes.

Identification of Microbes

• Morphology (e.g., coccus, bacillus),
• Staining (gram-positive or negative),
• Cell wall composition (e.g., presence or absence of peptidoglycan),
• Oxygen requirements (e.g., aerobic, facultatively anaerobic)
• Biochemical tests (e.g., which sugars are aerobically metabolized or fermented).

The most fundamental technique for classifying bacteria is the gram stain, developed in 1884 by Danish scientist Christian Gram. It is called a differential stain because it differentiates among bacteria and can be used to distinguish among them, based on differences in their cell wall.

The gram stain works best on young, growing populations of bacteria, and can be inconsistent in older populations maintained in the laboratory.

In addition to the gram stain, other stains include the acid-fast stain, endospore stain, negative stain, and flagella stain.

Another important identification technique is based on the principles of antigenicity- the ability to stimulate the formation of antibodies by the immune system.