decay
The term putrefaction covers a multitude of processes that take place after the death of an organism or after the death of parts of an organism. The term putrefaction is usually used in connection with animal organisms ( carrion or corpses in humans). In the case of plant material, one speaks of rotting , in the case of food, of spoilage . In the medical context, the process of tissue rot belongs to the symptom complex of necrosis .
Biochemical basics
Decay is caused by saprotrophic organisms, mainly bacteria and fungi . Enzymes released by these organisms break down complex organic compounds into smaller units, which are then completely oxidized to generate energy. But autolysis , i.e. decomposition by its own supravital enzymes, also plays a role.
Decay only takes place in the presence of oxygen , so it is aerobic. The organic compounds are then mainly broken down into water, carbon dioxide , urea and phosphate . In contrast, putrefaction processes predominate when there is no oxygen . Correspondingly, the decay of a larger organism takes place internally mainly through putrefaction, externally through putrefaction. In later stages of decomposition, decomposition processes predominate, provided that sufficient oxygen is available.
Putrefaction and ecology
In contrast to anaerobic putrefaction, higher organisms are often involved in putrefaction processes. Plant remains are eaten and broken up by worms , woodlice and insect larvae , for example , making them more accessible to microbial degradation. Animal carcasses are often eaten to a large extent by insects (for example carrion beetles , ants , bacon beetles ) or their larvae (for example fly maggots ) and nematodes . Depending on the prevailing environmental conditions, a specific " carrion fauna " develops when a larger organism decays .
The putrefaction in the upper soil layers leads to the formation of humus , and composting mainly includes putrefaction processes.
Period of decomposition
A dead body lying in the air decomposes about twice as fast as a corpse lying in water and eight times as fast as a buried one ( Casper's rule , overtaken by modern forensics ). A floater is after some time due to chemical reactions a soap-like substance, which receives the body shape and causes the body to slowly decay. This phenomenon of a so-called wax corpse has become a major problem in some cemeteries located in humid areas, since the decomposition period in some cases significantly exceeds the planned rest period of around 30 years.
Stages of decomposition of dead bodies lying in the air
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- Beginning rot
- Greasy
- Cheese-like products
- Ammoniac putrefaction
- Beginning of drying out
- Strong drying out
- Skeletonization
This gallery shows the decomposition process of a dead domestic pig lying in the open air :
Day 0
Day 4
Day 8
Day 11
Day 39
Smells
Various volatile and odorous substances are formed during putrefaction. Among other things, cadaverine , putrescine and other biogenic amines are formed in mammals . When humans decompose, characteristic mixtures of odorous compounds are created which are used, among other things, to find corpses with the help of corpse detection dogs .
literature
- Mark Benecke : Murder Methods. Investigations by the most famous forensic biologists in the world. Lübbe , Bergisch Gladbach 2002, ISBN 978-3-442-15394-7 .
- Mark Benecke: This is how modern criminal biology works. 6th edition, Lübbe, Bergisch Gladbach 2011, ISBN 978-3-404-60562-0 .
- Ernst Hallier: fermentation symptoms; Investigations on fermentation, putrefaction and putrefaction with consideration of miasms and contagias as well as disinfection, for doctors, naturalists, farmers and technicians. Engelmann, Leipzig 1867 ( limited preview in the Google book search).
- Mary Roach: Stiff: the curious lives of human cadavers. WW Norton, New York NY 2003, ISBN 0-393-05093-9 .
- Dirk Schoenen, Michael Carl Albrecht: The decomposition. Part 1: Dirk Schoenen: Putrefaction from a hygienic point of view. Part 2: putrefaction from a pedological point of view. In: Association for water, soil and air hygiene (Hrsg.): Series of publications by the association for water, soil and air hygiene. No. 113, Association for Water, Soil and Air Hygiene (WaBoLu), Berlin 2003, ISBN 3-932816-42-0 .
Web links
Individual evidence
- ^ Sarah Everts: Scientists search for death's aroma . In: Chemical & Engineering News (2016), Volume 94, Issue 14, pp. 16-18.