A group containing all the prokaryotic organisms (see prokaryote) with the exception of the blue-green algae. These however are included with the bacteria as Cyanobacteria in many classifications. Bacteria are found in virtually all habitats and, in terms of distribution and number, are the most successful of life forms. Many live sapro-phytically in the soil and are important as decomposers in the carbon cycle. Others, the nitrifying and denitrifying bacteria, are important in the nitrogen cycle. Some are pathogenic, causing rots, cankers, blights, and galls in plants and numerous diseases in animals, e.g. anthrax, brucellosis, and syphilis. Bacteria are important in many industrial processes. Fermenting bacteria, e.g. Acetobacter, Acetomonas, and Lactobacillus are widely used in the food industry. Cheese making and the production of silage are dependent on bacterial activity. Bacteria were once placed with the fungi in the class * Schizomycetes. They are now often classified as a separate division or kingdom, Bacteria or Prokaryota. The numerous different kinds of bacteria are classified on the basis of shape, size, growth form, staining and serological reactions, metabolic activity, and motility. See Eubacteriales, Pseudomonadales, Actinomycetales, Chlamydobacteriales, Beggiatoales, Myxobacteriales, Spirochaetales, Mycoplasmatales, Rickettsiales. |
