Poly-γ-glutamic acid: Recent achievements, diverse applications and future perspectives

Bacteria can synthesize a wide range of biopolymers that serve diverse biological functions and have material properties suitable for numerous industrial and medical applications. A better understanding of the fundamental processes involved in polymer biosynthesis and the regulation of these processes has created the foundation for metabolic- and protein-engineering approaches to improve economic-production efficiency and to produce tailor-made polymers with highly applicable material properties. Here, I summarize the key aspects of bacterial biopolymer production and highlight how a better understanding of polymer biosynthesis and material properties can lead to increased use of bacterial biopolymers as valuable renewable products.

Poly (γ-glutamic acid) (PGA) is water-soluble, anionic, biodegradable, and edible biopolymer produced by Bacillus subtilis. It has multifarious potential applications in foods, pharmaceuticals, healthcare, water treatment and other fields. The production of PGA has already been established on the industrial scale. Various studies regarding the fermentative production, downstream processing and characterization of PGA have been reported in the literature. This review provides updated information on fermentative production of PGA by various bacterial strains and effect of fermentation conditions and media component on production of PGA in submerged as well as solid state fermentation. Information on the application of genetic engineering for enhancement of yield of PGA, kinetic studies for production of PGA in submerged fermentation and recovery and purification of PGA is included. An attempt has also been made to review the current and potential applications of PGA. This review may contribute to further development of this commercially and academically interesting biopolymer. Copyright © 2011 Elsevier Ltd. All rights reserved.