Microbial production of poly-γ-glutamic acid

Poly-gamma-glutamic acid (gamma-PGA) is a natural, biodegradable and water-soluble biopolymer of glutamic acid. This review is focused on nonrecombinant microbial production of gamma-PGA via fermentation processes. In view of its commercial importance, the emphasis is on l-glutamic acid independent producers (i.e. microorganisms that do not require feeding with the relatively expensive amino acid l-glutamic acid to produce gamma-PGA), but glutamic acid dependent production is discussed for comparison. Strategies for improving production, reducing costs and using renewable feedstocks are discussed.