In this article we will discuss about:- 1. Meaning of Stains 2. Purpose of Staining 3. Structural Components 4. Classification. Meaning of Stains: A stain is any colouring organic compound that, when combined with another substance, imparts a colour to that substance. The terms 'dyes' and 'stains' are often used interchangeably by biologists, but they are not the same. The [...]
In this article we will discuss about the staining procedure used for detecting bacteria. 1. Simple Staining Procedure: When a single staining-reagent is used and all cells and their structures stain in the same manner, the procedure is called simple staining procedure. This procedure is of two types - positive and negative (Fig. 17.5). In positive staining, the stain (e.g., [...]
In this article we will discuss about the nutritional forms of microorganisms. 1. Photolithoautotrophs: This group includes photosynthetic microalgae, cyanobacteria, and photosynthetic bacteria (purple sulphur bacteria and green sulphur bacteria). In photosynthetic microalgae and cyanobacteria the external energy-source is light. One or more varieties of chlorophyll are present to trap the solar energy. Such microorganisms are, therefore, largely green. The [...]