Actinomadura monticuli sp. nov., isolated from Darangshi Oreum (a volcanic cone), and the reclassification of Actinomadura glauciflava Lu et al. 2003 as a later heterotypic synonym of Actinomadura luteofluorescens (Shinobu 1962) Preobrazhenskaya et al. 1975 (Approved Lists 1980)

Two mycelium-forming actinobacterial strains, designated as DLS-47 and DLS-62T, were isolated from volcanic ash collected from the surface of a rock on the peak of Darangshi Oreum (a volcanic cone) in Jeju, Republic of Korea, and their taxonomic positions were investigated by a polyphasic approach. Both of the isolates showed growth at 20-42 °C, pH 6.0-9.0 and 0-1% (w/v) NaCl. Furthermore, DLS-47 was found to grow at 45 °C, while strain DLS-62T grew at pH 10.0 and 3% (w/v) NaCl. The 16S rRNA gene-based phylogeny showed that both of the isolates belonged to the genus Actinomadura; strain DLS-47 was most closely related to Actinomadura chokoriensis DSM 45346T (100% sequence identity), while strain DLS-62T formed a tight cluster with Actinomadura bangladeshensis DSM 45347T (99.5% sequence similarity). Morphological and chemotaxonomic characteristics supported the affiliation of the two isolates to the genus Actinomadura. Phylogenomic analysis based on 92 core gene sequences showed that both of the isolates were most closely related to A. chokoriensis DSM 45346T. Strain DLS-47 shared 100% of orthologous average nucleotide identity and digital DNA-DNA hybridization values with A. chokoriensis DSM 45346T, while strain DLS-62T showed orthologous average nucleotide identity ≤89.8% and digital DNA-DNA hybridization values ≤39.4% with strain DLS-47 and members of the genus Actinomadura. The results of phenotypic assays and comparison of overall genomic relatedness indices support the conclusion that strain DLS-47 (= KACC 23347=DSM 116423) is a strain of A. chokoriensis, while strain DLS-62T (= KACC 23345T = DSM 116424T) represents a new species of the genus Actinomadura, for which the name Actinomadura monticuli sp. nov. is proposed. Also, Actinomadura glauciflava Lu et al. 2003 is reclassified as a later heterotypic synonym of Actinomadura luteofluorescens (Shinobu 1962) Preobrazhenskaya et al. 1975 (Approved Lists 1980) based on analysis of overall genomic relatedness indices and phenotypic similarity.

Actinomadura terrae sp. nov. and Actinomadura litoris OS3-89, isolated from rhizosphere soil of cactus

Two mycelium-forming actinobacterial strains, designated OS3-83 ^T and OS3-89, were isolated from rhizosphere soil of a cactus (Opuntia ficus-indica) sampled on Mara Island, Jeju, Republic of Korea. Both of the isolates were found to grow at 20-37 °C, pH 6.0-10.0 and with 0-2 % (w/v) NaCl. Their taxonomic positions were investigated by a polyphasic approach. Strains OS3-83^T and OS3-89 were most closely related to the type strain of Actinomadura litoris (99.5 % and 98.9 % 16S rRNA gene sequence similarity, respectively). Both of the isolates shared 99.2 % sequence similarity to each other. Morphological and chemotaxonomic characteristics supported the affiliation of the two isolates to the genus Actinomadura. 16S rRNA gene phylogeny exhibited that strain OS3-83^T formed a tight cluster with A. litoris, while strain OS3-89 occupied a position located remotely from A. litoris. Nevertheless, phylogenomic analysis based on 92 core gene sequences showed that both of the isolates formed a tight clade with A. litoris. The values of average nucleotide identity and digital DNA-DNA hybridization between strain OS3-83^T and the closest relative, A. litoris, were 92.2 and 46.2 %, respectively, whereas strain OS3-89 shared an average nucleotide identity value of 97.5 % and a digital DNA-DNA hybridization value of 76.9 % with A. litoris. These results strongly suggested that strain OS3-83^T (=KACC 19752^T=NBRC 114688^T) represents a novel species and strain OS3-89 (=KACC 19753=NBRC 114400) is a strain of A. litoris. On the basis of the data obtained here, strain OS3-83^T is considered to represent a new species of the genus Actinomadura, for which the name Actinomadura terrae sp. nov. is proposed.

Actinomadura harenae sp. nov., a novel actinomycete isolated from sea sand in Sanya

A novel actinomycete, designated strain NEAU-Ht49^T, was isolated from sea sand sampled in Sanya and characterized by using a polyphasic approach. The 16S rRNA gene sequence analysis showed that strain NEAU-Ht49^T was most closely related to Actinomadura rhizosphaerae SDA37^T (98.8 %), Actinomadura logoneensis NEAU-G17^T (98.6 %), Actinomadura oligospora ATCC 43269^T (98.6 %) and Actinomadura gamaensis NEAU-Gz5^T (98.6 %). The results of phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain NEAU-Ht49^T formed a cluster with A. rhizosphaerae SDA37^T, A. logoneensis NEAU-G17^T, A. oligospora ATCC 43269^T, A. gamaensis NEAU-Gz5^T and Actinomadura rupiterrae CS5-AC15^T (96.4 %). Meso-diaminopimelic acid was detected in its cell walls and glucose, madurose, mannose and ribose were detected in whole-cell hydrolysate. The polar lipids were found to consist of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositolmannoside and two unidentified lipids. The majoy menaquinone was MK-10(H₆) and the minor menaquinones were MK-9(H₄) and MK-9(H₈). The major fatty acids were C_16 : 0, C_18 : 1ω9c, 10-methyl C_18 : 0 and iso-C_16 : 0. Moreover, morphological and chemotaxonomic characteristics of properties of strain NEAU-Ht49^T also confirmed the affiliation of the isolate to the genus Actinomadura. However, DNA-DNA relatedness, physiological and biochemical data showed that strain NEAU-Ht49^T could be distinguished from its closest relatives. Therefore, strain NEAU-Ht49^T represents a novel species of the genus Actinomadura, for which the name Actinomadura harenae sp. nov. is proposed, with strain NEAU-Ht49^T (=CGMCC 4.7499^T=JCM 32659^T) as the type strain.

Actinomadura logoneensis sp. nov., a novel actinomycete isolated from the soil

One novel actinobacterial isolate, designated strain NEAU-G17^T, was isolated from muddy soil collected from a riverbank in Chad and characterised using polyphasic approach. Morphological and chemotaxonomic characteristics of this strain coincided with those of the genus Actinomadura. The 16S rRNA gene sequence analysis showed that strain NEAU-G17^T was most closely related to Actinomadura oligospora JCM 10648^T (98.7 %) and Actinomadura gamaensis NEAU-Gz5^T (98.6 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-G17^T formed a cluster with Actinomadura oligospora JCM 10648^T, Actinomadura gamaensis NEAU-Gz5^T and Actinomadura rupiterrae CS5-AC15^T (96.4 %). However, the combination of DNA-DNA hybridisation values and some phenotypic characteristics allowed the isolate to be differentiated from their most closely related species. The major menaquinones were identified as MK-9(H₄), MK-9(H₆) and MK-9(H₈). Their polar lipid profile was found to contain diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside, an unidentified phospholipid and an unidentified lipid. The major fatty acids were identified as C_16 : 0, iso-C_16 : 0 and C_18 : 1 ω9c. Therefore, it is proposed that strain NEAU-G17^T should be classified as representative of a novel species of the genus Actinomadura, for which the name Actinomadura logoneensis sp. nov. is proposed. The type strains is NEAU-G17^T (=CGMCC 4.7411^T=DSM 105122^T).

Rhodococcus antrifimi sp. nov., isolated from dried bat dung of a cave

A Gram-reaction-positive, high DNA G+C content, non-motile actinobacterium, strain D7-21T, was isolated from dried bat dung inside a natural cave and its taxonomic status was examined by using a polyphasic approach. The 16S rRNA gene sequence study showed that the isolate belonged to the genus Rhodococcus and formed a cluster with Rhodococcus defluvii (98.98 % gene similarity), Rhodococcus equi (98.62 %) and Rhodococcus kunmingensis (97.66 %). Whole-cell hydrolysates contained meso-diaminopimelic acid, arabinose and galactose as the diagnostic diamino acid and sugars. MK-8(H2) was the predominant menaquinone. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, an unknown phosphoglycolipid and an unknown glycolipid. Mycolic acids were present. The major fatty acids were C16 : 0, C18 : 1ω9c and 10-methyl C18 : 0. The DNA G+C content was 70.1 mol%. A battery of phenotypic features and DNA–DNA relatedness data support that strain D7-21T ( = KCTC 29469T = DSM 46727T) represents a novel species of the genus Rhodococcus, for which Rhodococcus antrifimi sp. nov. is proposed.

Actinomadura syzygii sp. nov., an endophytic actinomycete isolated from the roots of a jambolan plum tree (Syzygium cumini L. Skeels)

The taxonomic position of an endophytic actinomycete, strain GKU 157T, isolated from the roots of a jambolan plum tree (Syzygium cumini L. Skeels) collected at Khao Khitchakut National Park, Chantaburi province, Thailand, was determined using a polyphasic taxonomic approach. 16S rRNA gene sequence analysis revealed that strain GKU 157T belongs to the genus Actinomadura and formed a distinct phyletic line with Actinomadura chibensis NBRC 106107T (98.6 % similarity). Strain GKU 157T formed an extensively branched, non-fragmenting substrate mycelium and aerial hyphae that differentiated into hooked to short spiral chains of about 20 non-motile spores with a warty surface. The cell wall contained meso-diaminopimelic acid and the whole-cell sugars were galactose, glucose, madurose, mannose and ribose. The N-acyl type of muramic acid was acetyl. Mycolic acids were absent. The phospholipids included phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), phosphatidylinositol (PI), phosphatidylinositolmannoside (PIM) and two unknown phospholipids (PLs). The major menaquinone was MK-9(H6) and the predominant fatty acids were C16:0, iso-C16:0, C18:1ω9c, C18:0 and 10-methyl C18:0 (tuberculostearic acid). The genomic DNA G+C content was 73.1 mol%. A combination of DNA–DNA hybridization results and significant differences from related species in cultural, physiological and chemical characteristics indicated that strain GKU 157T represents a novel species of the genus Actinomadura, for which the name Actinomadura syzygii sp. nov. is proposed. The type strain is GKU 157T ( = BCC 70456T = NBRC 110399T).

Actinomadura darangshiensis sp. nov., isolated from a volcanic cone

An actinobacterium, designated strain DLS-70T, was isolated from a soil sample from the surface of a rock on the peak of Darangshi Oreum (a volcanic cone) in Jeju, Republic of Korea. Substrate mycelium was produced abundantly on most of the media tested. Spiral chains of spores with warty surface developed on the aerial hyphae. A phylogenetic tree based on 16S rRNA gene sequences showed that strain DLS-70T belonged to the genus Actinomadura and was most closely related to Actinomadura bangladeshensis DSM 45347T (98.9 % sequence similarity), Actinomadura madurae DSM 43067T (98.8 %) and Actinomadura chokoriensis DSM 45346T (98.6 %). Chemotaxonomic observations supported the assignment of the isolate to the genus Actinomadura . DNA–DNA relatedness values between strain DLS-70T and the type strains of the closest phylogenetic relatives were less than 20 %. On the basis of data from this polyphasic study, strain DLS-70T ( = KCTC 29224T = DSM 45941T) is considered to represent a novel species of the genus Actinomadura , for which the name Actinomadura darangshiensis sp. nov. is proposed.