Micromonospora cremea sp. nov. and Micromonospora zamorensis sp. nov., isolated from the rhizosphere of Pisum sativum.

Abstract

Three actinobacterial strains, CR30(T), CR36 and CR38(T), were isolated from rhizosphere soil of Pisum sativum plants collected in Spain. The strains were filamentous, Gram-stain-positive and produced single spores. Phylogenetic, chemotaxonomic and morphological analyses confirmed that the three strains belonged to the genus Micromonospora. 16S rRNA gene sequence analysis of strains CR30(T) and CR36 showed a close relationship to Micromonospora coriariae NAR01(T) (99.3% similarity) while strain CR38(T) had a similarity of 99.0% with Micromonospora saelicesensis Lupac 09(T). In addition, gyrB gene phylogeny clearly differentiated the novel isolates from recognized Micromonospora species. DNA-DNA hybridization, BOX-PCR and ARDRA profiles confirmed that these strains represent novel genomic species. The cell-wall peptidoglycan of strains CR30(T) and CR38(T) contained meso-diaminopimelic acid. Both strains had MK-10(H(4)) as the main menaquinone and a phospholipid type II pattern. An array of physiological tests also differentiated the isolates from their closest neighbours. Considering all the data obtained, it is proposed that strains CR30(T) and CR36 represent a novel species under the name Micromonospora cremea sp. nov. (type strain CR30(T) = CECT 7891(T) = DSM 45599(T)), whereas CR38(T) represents a second novel species, for which the name Micromonospora zamorensis sp. nov. is proposed, with CR38(T) ( = CECT 7892(T) = DSM 45600(T)) as the type strain.