Ch. 8— Maintaining Microbial Diversity • 207 



Table 8-1.— Summary of the Characteristics, Problems, and Uses of Micro-Organisms 



Organisms 



Characteristics 



Problems 



Uses 



Bacteria 



Fungi 



Algae 



Protozoa 



Viruses 



Single-cells; spherical rod and 

 spiral forms. Most are sapro- 

 phytes (use dead matter for 

 food), although some bacteria 

 are photosynthetic. 



Variety of forms; microscopic 

 molds, mildews, rusts, and 

 smuts; larger mushrooms and 

 puffballs. 



Single cells, colonies, or fila- 

 ments containing chlorophyll 

 and other characteristic pig- 

 ments; no true roots, stems, or 

 leaves; aquatic. 



Some cause disease in humans, 

 animals, and plants. 



Rot textiles, leather, harvested 

 foods, and other products; 

 cause important plant and 

 animal diseases. 



Cover pond surfaces, producing 

 scum and unpleasant odor and 

 taste (in drinking water); ab- 

 sorb Oi from ponds and some 

 produce toxins. 



Single cells, or groups of similar Responsible for serious human 



cells, found in fresh and sea 

 water, in soil, and as symbi- 

 onts or parasites in man, 

 animals, and some plants. 



Infective agents; capable of mul- 

 tiplying only in living cells; 

 composed of proteins and 

 nucleic acids. 



and animal disease (e.g., 

 malaria, sleeping sickness, 

 dysentery). 



Cause variety of human, animal, 

 and plant diseases (e.g., in- 

 fluenza, AIDS, rabies, 

 mosaics). 



Break down organic matter 

 and assist soil fertility, 

 waste disposal, and biogas 

 production; source of anti- 

 biotics and other 

 chemicals. 



Assist in recycling complex 

 plant constituents such as 

 cellulose; mushrooms and 

 yeasts important as foods; 

 many used in chemical and 

 pharmaceutical industries. 



Red and brown seaweeds are 

 important foods in Asia and 

 Polynesia; red algae 

 produce agar; important 

 food source for many ocean 

 fish. 



Assist in breakdown of organ- 

 ic matter such as cellulose 

 in ruminant nutrition. 



Important as carriers of genet- 

 ic information; some infect- 

 ing pests can be used as 

 biological control agents. 



SOURCE: National Academy of Sciences, Microbial Processes: Promising Techrtologies for Developing Countries (Washington, DC: National Academy Press. 1979). 



Pholo credit: GE. Pierce and M K. Mutks 



Pseudomonas putida, a bacterium capable of degrading 

 hydrocarbons, is one type of micro-organism. 



cell, are termed strains (7). Individually iden- 

 tifiable strains of micro-organisms are thus 

 often regarded as the basic units of microbial 

 diversity. 



Micro-organisms are found in nearly all envi- 

 ronments (8). Bacteria, for example, have been 

 found living in deep-sea steam vents at temper- 

 atures of 350° C (22). Although some micro-orga- 

 nisms are widely distributed, others may be 

 restricted to a narrow ecological range. Most 

 micro-organisms are found as parts of complex 

 microbial communities or as integral parts of 

 larger ecosystems. Many of these micro-orga- 

 nisms cannot be isolated and grown under con- 

 trolled laboratory conditions (25). 



Status of Microbial Diversity Onsite 



Assessing the status and changes in microbial 

 diversity onsite can be difficult. As noted 

 earlier, few micro-organisms have been isolated 



