Occurrence and Production of Poly-Epsilon-l-Lysine in Microorganisms

Abstract

This chapter addresses the occurrence and production of poly-e-L-lysine (e-PL) in filamentous bacteria from the family Streptomycetaceae and ergot fungi, especially in the genus Streptomyces. The presence of e-PL, first discovered from a strain among 2,000 actinomycetes, was found quite frequently in various strains of Streptomyces by novel screening methods, including the two-stage culture of cell growth and e-PL production cultures. Using the newly isolated producer strains of Streptomyces, their production behaviors were studied not only in terms of the time course of several production factors and effect of culture medium components, but also other aspects of the release of synthesized e-PL into the culture broth and of the simultaneous development of e-PL hydrolase activity with the e-PL-producing machinery. The e-PLs obtained were evaluated structurally. The results revealed that the polymers had a nearly monodispersed structure, and could be classified into five groups based on their chain lengths. The cell density-dependent control of the production of e-PL, the chain length shortening by aliphatic hydroxy-compounds, and the coproduction of novel amino acid homopolymers with e-PL are also discussed.