Bacteria

Many different bacteria species may appear in industrial water systems. Control, therefore, becomes extremely difficult because agents toxic to one species may have little effect on another. Bacteria may exist as single cells or multicellular colonies. In deference to the variety of species, they are categorized by physical and metabolic characteristics. The following table denotes some of those categories.

a. Shape	b. Temperature Requirements
Coccus - spherical Bacillus - rod shaped Spirillum - curved or comma shaped	Psychrophilic - cold liking (range: 0°C -20°C) Mesophilic - moderate temperature liking (range: 20°C - 45°C) Thermophilic - heat liking (range: 45°C -70°C)
c. Oxygen Requirements
Aerobic - need air to live Facultative Aerobe - can live with or without air; however, growth rate increases with the presence of air Facultative Anaerobe - can live with or without air; however, growth rate improves in the absence of air Anaerobic - must have absence of air to live Microaerophilic - need small amount of air to live d. Nutritional Requirements Autotrophic Bacteria - derive energy from the oxidation of inorganic materials Heterotrophic Organisms - obtain energy from metabolism of organic materials Parasitic Organisms - parasites which feed on living organic matter Saprophytic Organisms - subsist on dead or decaying matter

A partial list of some common bacterial types found in industrial water systems appears in Table below. This list is not all-inclusive, but is presented to show representative examples of the bacterial population, their characteristics and problems they cause in industrial water systems.