Environmental Engineering Reference
In-Depth Information
4.2. Metabolic and Genetic Engineering
The increasing availability of mathematical modeling tools, genomic and proteomic data
and techniques, and microarray and antisense RNA technology will allow increasingly
accurate prediction of useful targets for metabolic engineering. At the same time, genetic
manipulation within both microorganisms and plants is becoming increasingly possible and
rapid. Several enzymes central to PHA synthesis are just beginning to be explored through
combinatorial and rational design mutagenesis approaches, and efforts to understand their
catalytic mechanisms, substrate specificities, modes of competition with other enzymes, and
regulation are likely to contribute greatly to the microbial or plant-based syntheses of novel
polymers.
4.3. Reactor and Processing Technology
As described previously, gains in commercial feasibility are often found in improving
bioreactor yield and in diminishing processing costs. Without reiterating topics addressed
previously, it is nevertheless important to include these in the research priorities for PHA
efforts, with special note that the transfer of PHA synthesis to plants may circumvent many
limitations of both reactor efficiency and processing costs.
5. Commercialization
PHA-based materials were originally produced primarily under the trade name of
Biopol
TM
by ICI, Zeneca, and Monsanto. Metabolix recently acquired the Biopol
TM
patents
from Monsanto, however, and is now producing several PHA polymers in bacteria and plants.
Independently, Proctor and Gamble developed PHA copolymers of short and medium chain-
length monomers under the trade name NodaxTM and licensed the technology to the Kaneka
Corporation, a Japanese manufacturer of plastics and resins that is focusing on the production
of P(3HB-co-3HHX).
Nevertheless, Metabolix, Inc. currently possesses a virtual monopoly on the commercial
research and development of PHA polymers, holding approximately 90 issued U.S. patents
and approximately 40 additional pending U.S. patents, as well as their foreign equivalents,
protecting methods of PHA isolation, purification, and processing; use of several preferred
metabolic pathways for PHA copolymer production; and several novel PHA compositions
and specific applications. Most basic to Metabolix's position are the patents that give
Metabolix exclusive rights to the genes within the PHA biosynthesis pathway, as well as the
use of the genes in any combination for the preparation of PHAs (e.g., [57, 58]). As the
company states itself on its Web site, “Metabolix owns the genes that encode the basic PHA
pathway.” (http://www.metabolix.com/publications/patents.html).
This comprehensive ownership of intellectual property has given Metabolix the freedom
and protection to invest in research to improve PHA biosynthesis and processing
technologies, with which it has greatly advanced these fields, as evident from the preceding
discussion. At the same time, the present situation effectively diminishes or even deprives
potential competitors of the ability to use either microbes or plants to produce PHAs
commercially.
