Actinomadura keratinilytica sp. nov., a keratin-degrading actinobacterium isolated from bovine manure compost.

A novel keratinolytic actinobacterium, strain WCC-2265(T), was isolated from bovine hoof keratin 'baited' into composting bovine manure from southern Alberta, Canada, and subjected to phenotypic and genotypic characterization. Strain WCC-2265(T) produced well-developed, non-fragmenting and extensively branched hyphae within substrates and aerial hyphae, from which spherical spores possessing spiny cell sheaths were produced in primarily flexuous or straight chains. The cell wall contained meso-diaminopimelic acid, whole-cell sugars were galactose, glucose, madurose and ribose, and the major menaquinones were MK-9(H(6)), MK-9(H(8)), MK-9(H(4)) and MK-9(H(2)). These characteristics suggested that the organism belonged to the genus Actinomadura and a comparative analysis of 16S rRNA gene sequences indicated that it formed a distinct clade within the genus. Strain WCC-2265(T) could be differentiated from other species of the genus Actinomadura by DNA-DNA hybridization, morphological and physiological characteristics and the predominance of iso-C(16 : 0), iso-C(17 : 0) and 10-methyl C(17 : 0) fatty acids. The broad range of phenotypic and genetic characters supported the suggestion that this organism represents a novel species of the genus Actinomadura, for which the name Actinomadura keratinilytica sp. nov. is proposed; the type strain is strain WCC-2265(T) (=DSM 45195(T)=CCUG 56181(T)).