Bacteria Discussion

Microbes in wetland soils: Bacteria in wetland soils break down organic (carbon based) and inorganic (noncarbon based) structures. Most common are the Eubacteria and Archaebacteria kingdoms that include prokaryote bacteria. Most bacteria are heterotrophic, meaning they break down existing organic compounds to harvest the carbon and other atoms needed to survive. Bacteria can also be autotrophic meaning they manufacture their own organic molecules. They do this, depending on species, through photosynthesis using light, or chemosynthesis,oxidizing inorganic molecules to make organic molecules. (Solomon & Berg & Martin & Villee, 1993)

There are several kinds of photosynthetic bacteria, all Eubacteria. Cyanobacteria use red/blue light like algae and plants. The green sulfur, purple sulfur, green nonsulfur and purple nonsulfur use near infrared light. No water is involved so no oxygen is produced. The green sulfur bacteria have chlorophyll similar to chlorophyll a, but are anaerobic using hydrogen/sulfur compounds (H2S) not water (H20) as an electron donor. (Gould, James L.& Keeton, William T. with Grant, Carol, 1996) Sulfur bacteria use sulfur compounds as a hydrogen source producing sulfur as a byproduct. While most autotrophic bacteria are aerobic, some are anaerobic, and some can use oxygen or not (facultive anaerobes). (Solomon & Berg & Martin & Villee, 1993, pp. 515-523)

Among the chemosynthetic bacteria, carbon dioxide and hydrogen are often metabolized and produce byproducts of methane, water, and energy. Carbon and oxygen are electron acceptors in this reaction. Sulfur bacteria use a similar reaction but hydrogen and sulfur are used yield hydrogen sulfide and energy with sulfur accepting the hydrogen. Some chemosynthetic bacteria use arsenic, iron, manganese and uranium as electron receptors. (Gould.& Keeton with Grant, 1996, p. 154)

Archaebacteria are prokaryotes that live in extreme environments. Methanobacteria combine carbon dioxide and hydrogen found in sewage, digestive tracts, and wetlands to produce energy with methane as a byproduct. They are being used commercially to produce fuel from agricultural and residential waste. These abilities of chemosynthetic bacteria to synthesize inorganic elements make these useful in industrial and environmental processes.

Last updated: April 10, 2015

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