by ROBERT MARCHESSAULT
The American heartland of biobased plastics hosted the 20 year old ISBP meeting in Minneapolis. Professor Friedrich Srienc organized a meeting which brought together Cargill’s polylactide and Archer Daniel Midland’s polyhydroxy alkanoate biodegradable plastic ventures. At a time when polylactide is breaking production records and ADM is clearing the Clinton Iowa site for their new PHA biorefinery, 130 American, Asian and European researchers came together in Minneapolis. They shared the 49 oral presentations and 59 poster subjects on the campus of the University of Minnesota.
The two ventures are excitingly different: Cargill’s “semi-synthetic” and ADMs “100% bacterial,” both exploiting the cornbelt’s already strained supply to the bioethanol and biodiesal rush. Not since 1982 when Imperial Chemical Industries Ltd. (ICI) announced a totally biodegradable thermoplastic bacterial polyester has Green Chemistry seen so much cheering.
Bernd Rhem announced ISBP 2008 for Auckland, New Zealand.
Alexander Steinbuchel and his school reviewed the “Biology of
PHA” in terms of proteomes of PHA granules where the synthase remains attached
to the granules. PHA synthase is the only protein required for granule synthesis.
Systematic protein studies sketch the PHA inclusion as a complex organelle from
which tailor-made PHAs in chemostat cultures are made. The Metabolix vision
of a sustainable future through “Natural Plastics and Bioenergy” by deployment
of dedicated biomass crops such as switchgrass. It is estimated 370 million
tons of dedicated biomass crops will be needed by the year 2030. Meanwhile,
blown and cast films as well as extruded paper coatings and fuel alcohol will
proliferate. In Europe they do not have the land to produce needed biomass.
The use of photovoltaics is a better investment for conversion of Europe’s sun
energy. A major breakthrough in PHB biotechnology was the presentation of the
first three-dimensional structure of a type 2 extracellular depolymerase crystal.
This enzyme was capable to degrade insoluble PHB. The crystal was complexed
with a PHB trimer with a near-extended chain confirmation. Tepha, Inc. announced
poly-4-hydroxybutyrate flexible PHA, TephaFLEX , as materials for implantable
medical devices (absorbable sutures, textile mesh etc.). Several reports of
electrospun PHB fibers were presented for the first time.