Green Matter: Taming the PHB bug

11/02/2011

There's an old joke that goes: What did the male bacteria say to the female bacteria? Who needs biology when we have chemistry...Today, it looks as if the microbes may actually need both, at least when it comes to producing the bioplastic known as poly-3-hydroxybutyrate, or PHB. Researchers in Germany recently reported in the BioMed Central open access journal Microbial Cell Factories that they have found a method for rapidly producing this material in microalgae. No petroleum feedstock needed, just some fancy molecular biology and some simple chemistry.

PHB is a renewable material produced by bacteria as a storage compound, in response to stress from environment conditions. It is an aliphatic polyester with thermoplastic properties and is 100 % biodegradable into carbon dioxide and water.

The news about PHB is mostly good. It has a host of properties rendering it extremely suitable for a range of applications in which other bioplastics cannot even be considered. Unlike most bioplastics that are either water-soluble or sensitive to moisture, PHB is insoluble in water and resistant to hydrolytic degradation. It also has good permeability for oxygen molecules. It has a tensile strength of 40 Mpa, comparable to PP. The material is UV resistant, meaning it will not degrade when exposed to UV rays. It has a good thermal resistance, compared to, for example, PLA, which, unblended, starts to wilt at 60°C. As a result, PHB is also suitable for applications using higher temperatures....
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