Identification of an alkaliphilic actinomycetes that produces a PrPSc-degrading enzyme

Abstract

An alkaliphilic actinomycete strain TOA-1, that produces a PrPSc-degrading keratinase, was isolated from cement of bathroom tiles. This strain produced substrate and aerial mycelia. Growth occurred in the pH range 7.5–13.0, with an optimal pH of 10.0. A salt concentration of up to 8% was tolerated, and various organic substrates were used for growth. Strain TOA-1 contained meso-diaminopimelic acid, no diagnostic sugars, iso-C16:0 as the major cellular fatty acid, and MK-10, MK-10(H2), and MK-10(H4) as the predominant menaquinones. The G+C content was 71 mol%. All these characteristics, together with an analysis of its phylogenetic position, indicated that this strain belongs to the genus Nocardiopsis. DNA–DNA hybridization with its closest relative N. metallicus indicated a similarity of 55%, which suggested that strain TOA-1, deposited in the International Patent Organism Depositary National Institute of Advanced Industrial Science and Technology (FERM BP-08603) in Japan as a patent strain, represents a novel species of the genus Nocardiopsis.