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Worm guts have bacteria that apparently can degrade polyethylene:

The only agents that I have heard of that can degrade a fully-saturated hydrocarbon at room temperature are fluorine (and related nasties), other halogens (with UV light), magic acid (which is extremely reactive with almost anything). None of these seem biochemically feasible.

How is the polyethylene being attacked? Are the ends of the molecules more reactive double bonds that can be be broken off one carbon at a time like beta oxidation of fats?

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How is the polyethylene being attacked?

Polyethylene is attacked by microbes that contain oxygenase or oxidase enzymes. These enzymes can attack C-H bonds even at moderate temperatures.

The only agents that I have heard of that can degrade a fully-saturated hydrocarbon at room temperature are fluorine (and related nasties), other halogens (with UV light), magic acid (which is extremely reactive with almost anything).

One prominent example of a hydrocarbon degrading enzyme is methane monooxygenase, which is capable of catalyzing methane oxidation to methanol even at temperatures as low as 0 °C. The C-H bonds of polyethylene are about as reactive as methane's. (Actually, they're slightly more reactive.) Thus enzymes can do the job. They don't need elemental fluorine or magic acid.

However, your point about halogens reacting with hydrocarbons is very interesting. Several research groups have reported that adding halide salts to aqueous (and aerobic) suspensions of bacteria accelerates the rate of oxidation.

It's possible that this finding can be explained by the involvement of haloperoxidase enzymes in the degradation. However, the mechanism of microbial polyethylene degradation is a very new, and very active, area of ongoing research.

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  • $\begingroup$ Very good answer. $\endgroup$ – Kevin Kostlan Dec 10 '15 at 0:46
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from Wikipedia

Polythene or polyethylene film will naturally fragment and biodegrade, but it can take many decades to do this. There are two methods to resolve this problem. One is to modify the carbon chain of polyethylene with an additive to improve its degradability and then its biodegradability; the other is to make a film with similar properties to polyethylene from a biodegradable substance such as starch. The latter are however much more expensive.

So the cheap way is with a filler so that the film/part disintegrates not necessarily the polyethylene molecules of the polymer itself.

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