Definition: Single-celled microscopic organisms that lack nuclei and other organized cell structures.
"Bacteria" is the plural form of "bacterium." While several bacterial species are pathogenic (capable of causing disease), most are non-infectious, and many have critical roles in decay, fermentation, nutrient recycling, and nitrogen fixation. Bacteria are usually classified as gram-positive or gram-negative based on a basic microbiological staining procedure called the gram stain. They come in a variety of shapes and sizes. They may be shaped like rods, spheres or spirals.
Pronunciation: bac-TEER-ee-uh
Also Known As: prokaryotes, bugs
