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Air Pollution: Technology
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Air Quality and Energy Systems, 2020
One of the key processes on ecosystem level is the mineralization process, because it determines the cycling of nutrients. Heavy metals can inhibit the mineralization due to the blocking of enzymes. The effect is known not only for the enzymes produced in the organisms but also for extracellular enzymes—exoenzymes—originated from dead cells or excreted from roots and living microorganisms. As the various processes forming the cycling of nutrients are coupled, the entire mineralization cycle is disturbed if only one process is reduced. It is therefore possible to determine the change of the mineralization cycle by measuring the respiration, the transformation of nitrogen, and the release of phosphorus. As low a concentration of copper as 3–4 times the background concentration may imply a reduced soil respiration. A few hundred milligrams of copper per kilogram of soil is furthermore able to diminish the nitrogen release rate by one half.
Estimation of Bacterial Numbers by Indirect Methods
Published in Maria Csuros, Csaba Csuros, Klara Ver, Microbiological Examination of Water and Wastewater, 2018
Maria Csuros, Csaba Csuros, Klara Ver
Chemical reactions that occur within all living organisms are referred to as metabolism. Metabolic processes involve enzymes, which are proteins that catalyze biologic reactions. The majority of enzymes function inside a cell; that is, they are endoenzymes. Many bacteria make some enzymes, called exoenzymes, which are released from the cell to catalyze reactions outside of the cell.
A new enzymatic method assessing the impact of wastewater treatment plant effluents on the assimilative capacity of small rivers
Published in Journal of Environmental Science and Health, Part A, 2019
Dennis Langner, Bianca M. König, Denise J. Brettschneider, Andrea Misovic, Ulrike Schulte-Oehlmann, Jörg Oehlmann, Matthias Oetken
Microorganisms play a key role in the turnover of organic substances in surface waters and have also been used for toxicity tests for decades.[11–13] Extracellular enzymes (exoenzymes) are secreted by microorganisms and enable them to breakdown macromolecules such as cellulose and other (bio-) polymers. The extracellular breakdown of these macromolecules is critical for allowing the intracellular uptake of their constituents.[3] In WWTPs, for example, they are used in the activated sludge process to mineralize organic material under aerobic conditions.[14]