Gram Positive Bacteria

Gram positive bacteria describes a diverse class of bacteria. It is one of the basic classification of bacteria, by separating it from gram negative bacteria. When stained with several dyes, gram negative bacteria will stain pink, while gram positive bacteria will stain a dark purple. The major difference in the two bacteria is their cell walls. Gram positive bacteria have cell walls with a high amount of peptidoglycan which can be stained with a crystal violet dye. In a laboratory setting, the ability to distinguish between a gram positive and a gram negative organism is invaluable, especially when trying to determine a disease.

Gram positive bacteria have several characteristics that make them unique from other bacteria and microorganisms. They have a cytoplasmic membrane which serves to transport materials, nutrients, and waste in and out of the cell. They have a capsule which serves as a protective layer. Not all gram positive organisms have a capsule, but a great many do.

Some gram positive organisms have a flagellum with two rings for support. Gram negative organisms also have a flagellum, but with four rings instead of two. The flagellum serves to move the organism in its environment providing a way to receive nutrients as well as going away from organisms harmful to the bacteria. Others will from fimbrae which are used for attachment to anchor the bacteria. Once again, not all organisms have fimbrae, but many do.

Gram positive bacteria can take on a number of shapes. Many of them form coccus, or circular shapes. Under a microscope, they can be identified further by the pairing. Some have slightly flattened edges and come in pairs. These are known as diplococcus, and are easy to identify. Other circular bacteria will form clusters or lines, which help identify the particular kind of organism. These formations are protective usually and make a positive identification of the type of gram positive organism much easier. These organisms such as Streptococcus and Staphylococcus are often pathogenic in humans and will cause disease in the right circumstances. While some are harmless, it is important to know the potential for disease.

The bacteria can also form a bacillus or rod shaped. The rod shaped gram positive organisms are usually divided into spore forming or non spore forming. Members of the Bacillus bacteria will produce spores as a reproductive measure. Gram positive bacteria describes a group of microorganisms that is diverse in shape and function.





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Streptococcus bacteria

Streptococcus bacteria




Parent page: Gram Positive Bacteria