Aerobic organisms

Thiobacillus thiooxidans is an aerobic organism that oxidizes various sulfur-containing compounds to form sulfuric acid. These bacteria are sometimes found near the tops of tubercles (see Chap. 3, Tubercu-lation ). There is a symbiotic relationship between Thiobacillus and sulfate reducers Thiobacillus oxidizes sulfide to sulfate, whereas the sulfate reducers convert sulfide to sulfate. It is unclear to what extent Thiobacillus directly influences corrosion processes inside tubercles. It is more likely that they indirectly increase corrosion by accelerating sulfate-reducer activity deep in the tubercles. 

Aerobic (i) Having molecular oxygen as a part of the environment, (ii) Growing only in the presence of molecular oxygen, as in aerobic organisms, (iii) Occurring only in the presence of molecular oxygen, as in certain chemical or biochemical processes such as aerobic respiration. 

Biochemical oxygen demand (BOD) The molecular oxygen used in meeting the metabolic needs of aerobic organisms in aqueous medium containing an oxidizable organic molecule. 

Iron-Oxidizing Bacteria. These are aerobic organisms capable of growing in systems with less than 0.5 ppm oxygen. They oxidize iron from ferrous to the ferric state by the following mechanism ... 

The redox properties of quinones are crucial to the functioning of living cells, where compounds called ubiquinones act as biochemical oxidizing agents to mediate the electron-transfer processes involved in energy production. Ubiquinones, also called coenzymes Q, are components of the cells of all aerobic organisms, from the simplest bacterium to humans. They are so named because of their ubiquitous occurrence in nature. 

Cytochrome c is an enzyme found in the cells of all aerobic organisms. Elemental analysis of cytochrome c shows that it contains 0.43% iron. What is the minimum molecular weight of this enzyme ... 

Oxidative phosphorylation The greatest quantitative source of in aerobic organisms. Free energy... 

SUPEROXIDE DISMUTASE PROTECTS AEROBIC ORGANISMS AGAINST OXYGEN TOXICITY... 

Figure 16-2. The citric acid cycle the major catabolic pathway for acetyl-CoA in aerobic organisms. Acetyl-CoA, the product of carbohydrate, protein, and lipid catabolism, is taken into the cycle, together with HjO, and oxidized to CO2 with the release of reducing equivalents (2H). Subsequent oxidation of 2H in the respiratory chain leads to coupled phosphorylation of ADP to ATP. For one turn of the cycle, 11 are generated via oxidative phosphorylation and one arises at substrate level from the conversion of succinyl-CoA to succinate.

Sediment samples from a contaminated site were spiked with Arochlor 1242 and incubated at 4°C for several months (Williams and May 1997). Degradation by aerobic organisms in the upper layers of the sediment—but not in those at >15 mm from the surface—occurred with the selective production of di- and trichlorobiphenyls. Some congeners, including... 

In many situations, such as in deep groundwater, oxygen concentration may be severely limiting due to its consumption by surflcial aerobic organisms, or its low rate of transport into the system. Therefore, there has been great interest in the anaerobic degradation of BTEX. Although this has been... 

Use of the first oxidised products by proto-aerobic organisms - sulfate, ferric ions, and probably nitrogen oxides. Molybdenum became more available and was generally required for N and S metabolism (three to two billion years ago). 

---