steve%revolver@gatech.edu (12/09/89)
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A question has arisen on one or two other newsgroups recently whose
answer may be provided here. It involves the decomposition of a human
body after death.
What is the mechanism which causes the bloating which is observed shortly
after death? I think it involves anaerobic bacteria, but why do these same
bacteria not cause bloating when the person is alive. What has changed after
death (beyond the obvious) that was not happening when the person was alive.
How is the rate of decomposition affected by temperature? Please be as specific
as you possibly can.
*** The preceding statements represent the opinions of the author. ***
They must not be interpreted as representing the beliefs of any
other person, institution, government agency, or business entity. larry@kitty.UUCP (Larry Lippman) (12/11/89)
In article <1670@novavax.UUCP>, rwright@novavax.UUCP (Ronald K. Wright) writes: > > What is the mechanism which causes bloating which is observed shortly > >after death? I think it involves anaerobic bacteria, but why do these same > >bacteria not cause bloating when the person is alive. What has changed after > >death (beyond the obvious) that was not happening when the person was alive. > > Bloating of the body is caused by anaerobic bacterial growth. The term "putrefaction" specifically refers to the decomposition of proteins by anaerobic bacteria. > The anaerobes are the ones which live in your gut (and mine). In > life, our wonderful gut keeps them in. Die and they migrate via the > blood to inhabit the entire body. As they grow they release gasses > including methane, and some foul smelling guys called putricine and > cadavarine. In humans, the most common anaerobic bacteria responsible for putrefaction is Clostridium welchii, which is abundantly found in the colon. Proteolysis of the intestinal wall following death facilitates the rapid migration of Cl. welchii to the rest of the body. The first external sign of putrefaction is a greenish discoloration of the lower abdominal wall, typically occurring between 1 to 3 days following death. Temperature is unquestionably the most important factor in determining this time interval. The following are some examples of chemical mechanisms which occur during putrefaction: 1. Simple amino acids, such as alanine, will form propionic acid by deamination, and ethylamine through decarboxylation. 2. Some amino acids, such as tyrosine, have multiple mechanisms of deamination, decarboxylation, oxidation and reduction which entually produce an end product of phenol. 3. The predominant gaseous end products of putrefaction - methane and hydrogen sulfide - are produced by simultaneous deamination and decarboxylation of cysteine, which then produces methyl mercaptan (methanethiol) as an intermediate product. Methyl mercaptan, while not a gas, is extremely volatile and is one of the most odoriferous substances found in nature. 4. Decarboxylation of lysine produces cadaverine (1,5-diaminopentane). 5. Decarboxylation of ornithine produces putrescine (1,4-diaminobutane). A second mechanism for production of putrescine is facilitated by E. coli which cause decarboxylation of arginine; this mechanism also produces urea. 6. Decarboxylation of histidine produces histamine. 7. Tryptophan undergoes deamination to produce skatole (methyl indole), followed by indole itself. Skatole and indole are responsible for producing the characteristic odor of feces. Tryptophan also undergoes decarboxylation to form tryptamine. Detecting gaseous products of putrefaction, such as methane, hydrogen sulfide and volatized methyl mercaptan, has been used as a means to locate deceased victims in mass disasters. Typically, a portable industrial gas monitor with an air sampling probe is employed; the gas monitor device uses a sensitive electrochemical or thermal conductivity detection element. > Temperature speeds up decomp. In south Florida waters the summer > temperatures are 30-32 degrees. At this temperature a body floats at > 24 hours after death. Floating is caused by the gas. While putrefaction as described above is the primary mechanism behind the decomposition of a cadaver in water, other mechanisms exist, such as digestion by algae, destruction by carnivorous marine life, and physical damage by boat propellers, water intake pumps and hydroelectric turbines. In addition, starting only a few days after death (but not being usually noticeable for some weeks), fats in a body undergo hydrolysis to form a waxy substance called adipocere. Adipocere requires an exposure to water, and forms on the skin and subcutaneous fat first, while eventually proceeding to within the body. Adipocere is composed primarily of fatty acids, whose formation then inhibits further bacterial putrefaction. Note the distinction between "putrefaction" and "decomposition", with the former being but a subset of the latter. Significant adipocere formation reduces the specific gravity of a body, making it easier to float. <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {allegra|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"