Gamma-poly-glutamic acid (γ-PGA) is a natural occurring, multi-functional, and biodegradable biopolymer. It is produced through fermentation by Bacillus subtilis using glutamic acid. PGA is consists of glutamic acid monomers crosslinked between α-amino and γ-carboxyl groups, and the molecular weight of PGA is usually between 100~1000 kDa. It is water-soluble, edible and non-toxictowards human, and is environment friendly. It has broad applications in the fields of medicine, food, cosmetics, and water treatment.