polymer producing bacteria

Gilles Lefebvre seeker at sbox.tu-graz.ac.at
Sat Nov 4 07:57:28 EST 1995

R. Lee Steensland (bnorse at eskimo.com) wrote:
: Does anyone have ANY informaion about a bacteria that produces a 
: biodegradable plastic in its cells?  I heard about them several months 
: ago, and I would like to find more information about them.  These bacteria 
: were part of a genetics experment I recall.  These particular bacteria 
: have a slow growthrate, so scientists removed the polymer gene from that 
: bacteria and inserted it into another bacteria with a faster growthrate, 
: thereby producing more polymer...
: Thanks...

	There are dozens of genera of bacteria that naturally produce
polyhydroxyalkanoates, or PHAs, as carbon and energy reserve materials.
Once extracted from the producing cells, PHAs have a wide range of
properties, depending on their composition. The most common PHA is
the homopolymer poly-3-hydroxybutyrate, or P(3HB), which is stiff and brittle
(and resembles polypropylene in many ways). When other monomers are present,
PHAs can display very interesting thermoplastic properties. PHAs are
biocompatible and readily biodegradable in microbe-rich, moist environments
(e.g., compost heaps). They can be produced in large quantities by a variety
of fermentation methods and the imposition of growth-limiting, carbon-rich
culture conditions.
	PHAs are already produced in tonne quantities by England's Zeneca
Bio Products and marketed in the USA (tradename: PHBV), Europe (tn: Biopol)
and Japan, mostly as packaging for personnal cosmetics. The bacterium
Zeneca uses is NOT a recombinant strain. But the PHA genes have indeed been
cloned in other organisms (usually E. coli). This has been done more to
allow sequencing of the genes and get an insight into PHA metabolism than to
produce "more" polymer.
	Many laboratories around the world are active in research on PHAs.
Labs in the USA, Canada, Great Britain, Japan, Korea, Germany, Austria,
Switzerland, France, Holland, Spain, and many others, do research on PHAs. A
lot of it is directed at reducing the cost of producing PHAs, whose price is
still much higher than that of petroleum-based plastics.

Gilles Lefebvre alias seeker at sbox.tu-graz.ac.at
University of Technology of Graz, Austria

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