THE ROLE OF MICRO-ORGANISMS IN THE DECOMPOSITION OF ORGANIC MATTER AND THE RECYCLING OF CARBON

TRUE OR FALSE?1. Decomposition is described as having three components

(True/False)2. The skin turns to different shades of brown and green

during decomposition (True/False)3. Bacteria produce gases causing the body to bloat

(True/False) 4. The Salmonella bacteria is found on a corpse (True/False)5. Decomposition isn’t a part of the carbon cycle

(True/False) 6. Carbon Dioxide is released into the atmosphere by

respiring decomposers (True/False)

Answers: 1. False (there are only two) 2. True 3.True 4. True 5. False 6. True

ROLE OF MICROORGANISMS IN THE DECOMPOSITION OF ORGANIC MATTER

Decomposition refers to the breakdown of the body which occurs following a death

Two Components of Decomposition• Decomposition is described as having two components;

autolysis and putrefaction. • Autolysis refers to the situation where the body’s own enzymes

are acting on itself, causing cellular and tissue destruction.• Putrefaction refers to the situation where microorganisms

(especially bacteria and fungi) feed on and break down the tissues of the dead body.

Process of Decomposition by Microorganisms

• Within a very short time period microorganisms can breakdown and digest a large amount of soft tissue, resulting in a large production of gas and ‘decomposition fluid’

• As decomposition proceeds, the skin begins to darken to various shades of green and brown. This is usually first seen within the right lower abdominal quadrant (image below)

• The body becomes somewhat bloated due to the decomposition gases produced, and the decomposition fluid is frequently expelled from the mouth, nose or other opening in the presence of a red-brown fluid

ROLE OF MICROORGANISMS IN THE RECYCLING OF CARBON

Bacteria and fungi contribute to the decay of the body.

Other decomposers• Insects are not the only organisms involved in decomposition of

a body. • Bacteria also plays a major role. • Those found in the gut invade the dead tissues after death of a

body as well as other fungi and bacteria from surroundings colonising the corpse.

• This in turn leads to decay.• There is no set succession on the particular sequence of

succession however genera often found on corpses include Bacillus, Candida and Argobacterium.

• These are collectively known as decomposers.

Microorganisms Found on Corpses Early Stages of decomposition:• Bacillus• Staphylococcus• Candida• StreptococcusFollowed by:• Salmonella• Cytophaga• Agrobacterium

Bacillus

Streptococcus

Salmonella

Microorganisms are Collectively known as Decomposers• Decomposers obtain a great source of energy from the body

such as proteins, fats, organic carbohydrates and nucleic acids which are used as a food source.

• This energy is then released through aerobic/anaerobic respiration.

• This energy allows rapid multiplication which leads to more decomposition.

The Carbon Cycle

EXAM QUESTIONS