Biodegradation of polyamides

Naturally occurring homopolyamides are linear poly(amino acids) consisting either of glutamic acid (poly[gamma glutamic acid], gamma-PGA), lysine (poly[epsilon lysine]) or arginylaspartic acid (poly[alpha arginylaspartic acid], cyanophycin). gamma-PGA is synthesized as the major component of capsules and slimes of several Gram-positive bacteria. Purified gamma-PGA produced by Bacillus licheniformis ATCC9945 is a high molecular weight, water-soluble white powder leading to highly viscous solutions at low concentrations, and is resistant to proteolytic attack. While the synthesis of gamma-PGA has been investigated since its discovery in 1937, not much work has been done on the biodegradation of the polymer. A screening for gamma-PGA-degrading microorganisms led to the identification and characterization of 12 bacteria species. In this paper, the results of physiological and biochemical investigations concerning the degradation of poly(gamma glutamic acid) are presented. (C) 1998 Elsevier Science Limited. All rights reserved.