Metabolix Transfers PHA Genes into Switchgrass -- How Cool is That?

Polyhydroxybutanolate, a PHA

C&E News is reporting that Metabolix, who sells the PHA polymer Miral, has successfully transferred genes to make PHA to switchgrass Panicum virgatum at a dry weight of 6% -- up from 3.7%. The PHA forms in the chloroplasts rather than in the cell walls. The research had previously been published in Plant Biotechnol. J. 2008, 6, 663. 

Unlike polylactic acid, PHA's are (somewhat) hydrophobic and don't spontaneously degrade in water so one can make useful materials from them.

An opportunity/problem with them is that they are usually a mixture of different alkyl lengths, lengths that can be manipulated by controlling the feedstocks.

Metabolix has a 110 million pound plant in a JV with ADM called Telles.

Miscanthus giganteus, a relative of switchgrass
I can't resist reusing this picture though. 

The problem with PHA is extracting it from the bacteria they are made from. This makes the price too high for common applications, $1.80-2.00/lb or $4/kg. The hope is new switchgrass based technique is that it will be productive enough to pay for the extraction.

The other prospect is that the waste products from the switchgrass production could be used in to make cellulosic ethanol or otherwise be enzymatically degraded to make useful chemicals.