Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/15/2008
Publication Date: 7/22/2008
Citation: Mcmahan, C.M., Whalen, M.C. 2008. High-performance stereospecific elastomers from bioreactors. International Latex Conference, Cleveland, OH, July 22-23, 2008. pp 130-143. Interpretive Summary: Domestic natural rubber must replace Hevea rubber in existing applications, but direct substitution is not possible due to inherent differences. Our interspecific studies have led to development of a hypothesis that species-specific differences manifested in rubber performance are due not to the polymer per se, but to the presence of non-rubber constituents such as proteins and fatty acids that can associate with the rubber molecules. A better mechanistic understanding of the properties of rubber from new crops has direct impact on industrial conversion to domestic rubber sources. Strategies to overcome the sometimes disadvantageous effects of these constituents are the subject of ongoing research.
Technical Abstract: In 2008, 10 million tons of natural rubber, cis-1,4-polyisoprene, will be produced for commercial use. Every molecule of that product will be produced in a microscopic bioreactor known as the rubber particle. These particles, suspended in an aqueous phase called latex, evolved to produce and store natural rubber in plants. Their robust nature allows them to be exploited by industry once the particles have been harvested from the plants. Through studies of the chemistry and biology of rubber particles, a more detailed understanding of this dynamic and complex bioreactor system is emerging. Rubber particles are stabilized by lipid monolayer membranes and produce polyisoprene of specific (usually cis-1,4) microstructure. The particle itself has all the essential machinery for rubber production, and maintains biosynthetic activity for a period of time following harvest. Rubber is produced in a wide range of plants; the molecular weight varies by species and within a species. Remarkably, particles isolated from different plants show species-specific traits such as particle size, lipid content, and biometric protein profile. It is already known that the presence of low levels of non-rubber constituents have important consequences in industrial use. Such components and their chemical and biological activity vary with environmental factors, complications that are a consequence and an opportunity in a biological system.