Polyhydroxybutyrate

Polyhydroxybutyrate (PHB) is a polymer of hydroxybutyrate (HB) monomers. It is a type of polyhydroxyalkanoates (PHA), a class of polyesters produced in nature by numerous microorganisms, including through bacterial fermentation of sugar or lipids.

Structure and Properties

PHB is a linear polyester with a high degree of crystallinity, which results in a high melting point (175 °C) and glass transition temperature (2 °C). It is resistant to ultraviolet radiation and is highly biodegradable, making it suitable for certain applications in the medical field and packaging industry.

Production

PHB is produced by microorganisms in response to conditions of physiological stress, primarily a lack of nutrients. The most common method of production is through bacterial fermentation of glucose or starch. The bacteria Cupriavidus necator, formerly known as Ralstonia eutropha and Alcaligenes eutrophus, is the most widely used for this purpose.

Applications

Due to its biodegradability and biocompatibility, PHB has been extensively studied for use in the medical field. It has potential applications in drug delivery, tissue engineering, and as a surgical suture. In the packaging industry, PHB is used as an environmentally friendly alternative to petroleum-based plastics.

Environmental Impact

As a biodegradable and renewable resource, PHB has the potential to reduce the environmental impact of plastic pollution. However, its production process can be energy-intensive and may contribute to greenhouse gas emissions if not managed properly.

See Also

• Polyhydroxyalkanoates
• Biodegradable plastic
• Biopolymer
• Bacterial fermentation