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Microbiological Aspects
Published in Héctor A. Videla, Manual of Biocorrosion, 2018
According to the carbon source used by the microorganisms for their metabolism, energy production, and synthesis of organic matter, they can be classified as autotrophs (obtaining carbon from carbon dioxide) and heterotrophs (obtaining carbon from organic matter). A scheme of carbon and energy sources for autotrophic and heterotrophic microorganisms is outlined in Figure 2.6. Autotrophic organisms can be classified as (1) chemosynthetic. when they obtain energy from the oxidation of inorganic compounds such as Nitrosomorias and Nitrobacter in the nitrification process, Beggiatoa in sulfur oxidation, and Gallionella in iron oxidation; and (2) photosynthetic, when they obtain energy from the sun to accomplish the synthesis of organic matter and cellular material from carbon dioxide and water, producing molecular oxygen, like the algae. According to the requirements of oxygen, the microorganisms can be classified as (1) aerobic organisms, when they use dissolved oxygen for their metabolic processes, being unable to live in its absence; (2) anaerobic organisms, when they live in anaerobic environments, because oxygen is toxic for them; and (3) facultative organisms, when they are able to grow either in aerobic or anaerobic media, being able to use the oxygen linked to oxidized inorganic compounds such as nitrates, nitrites, sulfates, and phosphates. Due to the wide variation of oxygen concentrations generally found either in industrial environments or in biological deposits and biofilms, the respiratory characteristics of the microorganisms play a relevant role in corrosion, where oxygen reduction is generally the main cathodic reaction.
Values, Alterations and Degradation of the Natural Landscape
Published in Kimon Hadjibiros, Ecology and Applied Environmental Science, 2013
The ocean is the oldest, largest and more stable ecosystem of the planet. Its function is determinately influenced by natural factors, such as surge, tide, currents, salinity, temperature, pressure and intensity of radiation. Trophic chains begin with the smaller known producer organisms and end with the biggest animals of the planet. In great depths, near geothermal springs, isolated ecosystems develop with unique characteristics in which primary production is not based on photosynthetic organisms but on chemosynthetic bacteria.
Microbiological drinking water parameters
Published in Frank R. Spellman, The Drinking Water Handbook, 2017
Chemosynthesis is the synthesis of organic substances such as food nutrients using the energy of chemical reactions. Bacteria that obtain carbon from carbon dioxide are called autotrophic. Bacteria that obtain carbon through organic compounds are called heterotrophic (see Figure 6.3).
Diatomic sulfur: a mysterious molecule
Published in Journal of Sulfur Chemistry, 2019
In 1887, S. N. Vinogradsky first proved the possibility of using energy released during conversion of hydrogen sulfide to assimilate carbon dioxide, thus opening chemosynthesis in contrast to photosynthesis well known at that time. He suggested using the term ‘sulfur bacteria’ for microorganisms that accumulate elemental sulfur in the cell, if they live in suitable conditions in water containing hydrogen sulfide. Chemosynthesis is a method of autotrophic feeding of microorganisms, in which the energy source for the synthesis of organic substances from CO2 is the oxidation reactions of inorganic compounds. Autotrophic bacteria are organisms that synthesize organic substances from simple inorganic compounds [40].