Nonomuraea thermotolerans sp. nov., a thermotolerant actinomycete isolated from mushroom compost.

Abstract

A novel thermotolerant actinomycete, designated strain 3-33-9BT, was isolated from mushroom compost in Nanning, Guangxi province, China. The strain grew at 25-60 °C, pH 7.0-11.0 and with 0-2.0 % (w/v) NaCl. Strain 3-33-9BT formed extensively branched aerial mycelia and substrate mycelia. Spiral spore chains with one to three turns were composed of about 3-15 non-motile spores with a wrinkled surface. The organism contained meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan. Whole-cell hydrolysates contained madurose, galactose, glucose and ribose. The cellular fatty acid profile mainly consisted of iso-C16 : 0 and C17 : 0. The quinone system was predominantly composed of MK-9(H4). The DNA G+C content of strain 3-33-9BT was 72.5 mol%. The organism showed a combination of morphological and chemotaxonomic properties typical of members of the genus Nonomuraea. Moreover, 16S rRNA gene sequence analysis also showed that the organism belonged to the genus Nonomuraea; in the 16S rRNA gene tree of the genus Nonomuraea, strain 3-33-9BT formed a distinct phyletic line and was most closely related to Nonomuraea fastidiosa NBRC 14680T (97.3 % 16S rRNA gene sequence similarity). However, phenotypic characteristics of strain 3-33-9BT were significantly different from N. fastidiosa NBRC 14680T, and DNA-DNA hybridization showed little relatedness (31.6-35.2 %) between the two strains. Based on the phenotypic and phylogenetic data, strain 3-33-9BT represents a novel species of the genus Nonomuraea, for which the name Nonomuraea thermotolerans sp. nov. is proposed. The type strain is 3-33-9BT ( = ATCC BAA-2629T = CGMCC 4.7161T).