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

Abstract

Three actinobacterial strains, CR30T, CR36 and CR38T, were isolated from rhizosphere soil ofPisum sativumplants 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 genusMicromonospora. 16S rRNA gene sequence analysis of strains CR30Tand CR36 showed a close relationship toMicromonospora coriariaeNAR01T(99.3 % similarity) while strain CR38Thad a similarity of 99.0 % withMicromonospora saelicesensisLupac 09T. In addition,gyrBgene phylogeny clearly differentiated the novel isolates from recognizedMicromonosporaspecies. DNA–DNA hybridization, BOX-PCR and ARDRA profiles confirmed that these strains represent novel genomic species. The cell-wall peptidoglycan of strains CR30Tand CR38Tcontainedmeso-diaminopimelic acid. Both strains had MK-10(H4) 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 CR30Tand CR36 represent a novel species under the nameMicromonospora cremeasp. nov. (type strain CR30T = CECT 7891T = DSM 45599T), whereas CR38Trepresents a second novel species, for which the nameMicromonospora zamorensissp. nov. is proposed, with CR38T( = CECT 7892T = DSM 45600T) as the type strain.