Taxonomic Revision of the Actinomycete Genera Actinomadura and Microtetraspora

Nonomuraea corallina sp. nov., isolated from coastal sediment in Samila Beach, Thailand: insights into secondary metabolite synthesis as anticancer potential

A novel marine actinomycete, designated strain MCN248T, was isolated from the coastal sediment in Songkhla Province, Thailand. Based on the 16S rRNA gene sequences, the new isolate was closely related to Nonomuraea harbinensis DSM45887T (99.2%) and Nonomuraea ferruginea DSM43553T (98.6%). Phylogenetic analyzes based on the 16S rRNA gene sequences showed that strain MCN248T was clustered with Nonomuraea harbinensis DSM45887T and Nonomuraea ferruginea DSM43553T. However, the digital DNA-DNA hybridization analyzes presented a low relatedness of 40.2% between strain MCN248T and the above closely related strains. This strain contained meso-diaminopimelic acid. The acyl type of the peptidoglycan was acetyl, and mycolic acids were absent. The major menaquinones were MK-9(H2) and MK-9(H4). The whole cell sugars consisted of madurose, ribose, mannose, and glucose. Diphosphatidylglycerol, hydroxyl-phosphatidylethanolamine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylglycerol were detected as the major phospholipids. The predominant cellular fatty acids were iso-C16:0 (40.4%), 10-methyl-C17:0 (22.1%), and C17:1ω 8c (10.9%). The DNA G + C content of the genomic DNA was 71.7%. With in silico analyzes, the antiSMASH platform uncovered a diverse 29 secondary metabolite biosynthesis arsenal, including non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) of strain MCN248T, with a high prevalence of gene cluster encoding pathways for the production of anticancer and cytotoxic compounds. Consistently, the crude extract could inhibit colorectal HCT-116 cancer cells at a final concentration of 50 μg/mL. Based on the polyphasic approach, strain MCN248 was designated as a novel species of the genus Nonomuraea, for which the name Nonomuraea corallina sp. nov. is proposed. The type strain of the type species is MCN248T (=NBRC115966T = TBRC17110T).

Actinomadura spongiicola sp. nov., isolated from the marine sponge Leucetta chagosensis

A novel actinomycete strain, named LHW52907T, was isolated from a marine sponge (Leucetta chagosensis) collected in the South China Sea. The strain developed branched mycelia without fragmentation and short spore chains in hook-and- spiral form with wrinkled surfaces, bearing no more 10 spores. The cell-wall hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid. The sugars in whole-cell hydrolysates consisted of mannose, ribose, glucose, galactose and madurose. The major fatty acids of the strain were C16 : 0, C17 : 0 and C18 : 1  ω9c. The predominant menaquinone was MK-9(H6). The strain had the highest 16S rRNA gene sequence similarity of 99.72 % to Actinomadura pelletieri DSM 43383T. However, the average nucleotide identity and in silico DNA–DNA hybridization values between them were 93.6 and 52.6 %, respectively, readily distinguishing them as two different species. The results indicate that strain LHW52907T represents a novel species of the genus Actinomadura , for which we propose the name Actinomadura spongiicola sp. nov, with the type strain LHW52907T (=DSM 106571T=CGMCC 4.7596T).

Actinomadura violacea sp. nov., a madurastatin A1-producing strain isolated from lichen in Thailand

An actinomycete strain, LCR2-06^T, isolated from a lichen sample on rock collected from Chiang Rai Province (Pong Phra Bat Waterfall), Thailand, was characterized using a polyphasic approach. The strain grew at 25-45 °C, pH 6-11 and on International Streptomyces Project 2 agar plate with 5 % (w/v) NaCl. It contained meso-diaminopimelic acid as the diamino acid in whole-cell hydrolysates. Rhamnose, ribose, xylose, madurose, glucose and galactose were detected as whole-cell sugar hydrolysates. Mycolic acids were absent. The N-acyl type of muramic acid was acetyl. The strain contained C_16 : 0, TBSA 10-methyl C_18 : 0 and 2-hydroxy C_16 : 0 as the predominant fatty acids and MK-9(H₆), MK-9(H₄) and MK-9(H₈) as the major menaquinones. The major polar lipids were diphosphatidylglycerol, phosphatidylinositol and unidentified phospholipid. The draft genome of strain LCR2-06^T was closely related to Actinomadura barringtoniae TBRC 7225^T (99.2 %), Actinomadura nitritigenes NBRC 15918^T (98.8 %), Actinomadura montaniterrae TISTR 2400^T (98.5 %) and Actinomadura physcomitrii JCM 33455^T (97.9 %). The draft genome of LCR2-06^T was 11.1 Mb with 10 588 coding sequences with an average G+C content of 72.7 mol%. Results of genomic analysis revealed that the ANIb and ANIm values between strain LCR2-06^T and A. montaniterrae TISTR 2400^T were 90.0 and 92.0 %, respectively. The digital DNA-DNA hybridization value was 43.9 % in comparison with the draft genome of A. montaniterrae TISTR 2400^T. The strain produced an antibacterial compound active against Bacillus subtilis ATCC 6633 and Kocuria rhizophila ATCC 9341. The results of taxonomic analysis suggested that strain LCR2-06^T represented a novel species of the genus Actinomadura for which the name Actinomadura violacea sp. nov. is proposed. The type strain is LCR2-06^T (=JCM 33065^T=KCTC 49547^T=NBRC 114810^T=LMG 32136^T=TISTR 2935^T).

Actinomadura graeca sp. nov.: A novel producer of the macrocyclic antibiotic zelkovamycin

As part of a screening programme for antibiotic-producing bacteria, a novel Actinomadura species was discovered from a soil sample collected in Santorini, Greece. Preliminary 16S rRNA gene sequence comparisons highlighted Actinomadura macra as the most similar characterised species. However, whole-genome sequencing revealed an average nucleotide identity (ANI) value of 89% with A. macra, the highest among related species. Further phenotypic and chemotaxonomic analyses confirmed that the isolate represents a previously uncharacterised species in the genus Actinomadura, for which the name Actinomadura graeca sp. nov. is proposed (type strain 32-07T). The G+C content of A. graeca 32-07 is 72.36%. The cell wall contains DL-diaminopimelic acid, intracellular sugars are glucose, ribose and galactose, the predominant menaquinone is MK-9(H6), the major cellular lipid is phosphatidylinositol and fatty acids consist mainly of hexadecanoic acid. No mycolic acid was detected. Furthermore, A. graeca 32-07 has been confirmed as a novel producer of the non-ribosomal peptide antibiotic zelkovamycin and we report herein a provisional description of the unique biosynthetic gene cluster.

Actinomadura soli sp. nov., isolated from the top soil layer on basaltic material in Turkey

An actinobacterium, designated 14C53^T, was isolated from a soil sample on basaltic material from Samsun, Turkey. The growth ranges for NaCl concentration and pH of strain 14C53^T were quite limited and the growth temperature range of the strain was 20-37 °C, with an optimum at 28 °C. Phylogenetic analysis of 16S rRNA gene sequences revealed that strain 14C53^T was most closely related to Actinomadura geliboluensis A8036^T (98.5 % similarity value), but in the phylogenetic tree, it formed a clade with Actinomadura alkaliterrae D310A^T. The genome tree revealed a close relationship between the strain and Actinomadura pelletieri DSM 43383^T. However, the digital DNA-DNA hybridization and average nucleotide identity values between strain 14C53^T with Actinomadura geliboluensis A8036^T and Actinomadura pelletieri DSM 43383^T were 28.6-30.2 % and 84.3-85.5 %, respectively, and comparative analyses based on the genome sequences demonstrated that it represents a novel species of the genus Actinomadura. The genome size of strain 14C53^T was approximately 9.0 Mb and the genomic DNA G+C content of the strain was 71.3 mol%. The major cellular fatty acids of strain 14C53^T were C_16 : 0 and iso-C_16 : 0. Strain 14C53^T contained meso-diaminopimelic acid as the diamino acid in the cell-wall peptidoglycan. The predominant menaquinones were MK-9(H₈) and MK-9(H₆). Based on evidence collected from the phenotypic, genotypic and phylogenetic analyses, a novel species Actinomadura soli sp. nov. is proposed, with 14C53^T (=DSM 104447^T=KCTC 39878^T) as the type strain.

Streptomyces scabichelini sp. nov., isolated from soil

A novel actinomycete, designated strain HC44^T, was isolated from a soil sample collected from Hacibektaş, Turkey, and characterized using a polyphasic approach. The strain had morphological characteristics and chemotaxonomic properties identical to those of members of the genus Streptomyces. Phylogenetic analyses based on 16S rRNA gene sequence comparisons revealed that HC44^T clustered with members of the genus Streptomyces and the highest 16S rRNA gene sequence similarity values were obtained with Streptomyces vastus NBRC 13094^T (97.6 %) and Streptomyces kalpinensis TRM 46509^T (96.9 %). Multi-locus sequence analysis (MLSA) based on five housekeeping genes (atpD, gyrB, recA, rpoB and trpB) showed that the MLSA evolutionary distance value was 0.043 between strain HC44^T and S. vastus NBRC 13094^T. Whole-cell hydrolysates contained ll-diaminopimelic acid, glucose, mannose and ribose. The predominant menaquinones were MK-9(H₆) and MK-9(H₈). The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The DNA G+C content of the draft genome sequence, consisting of 11.2 Mbp, was 69.8 mol%. On the basis of polyphasic taxonomic evidence, strain HC44^T represents a novel species of the genus Streptomyces, for which the name Streptomyces scabichelini sp. nov. is proposed. The type strain is HC44^T (=DSM 106874^T=KCTC 39872^T).

Actinomadura litoris sp. nov., an actinobacterium isolated from sandy soil in Sanya

A novel actinobacterium, designated strain NEAU-AAG5^T, was isolated from sandy soil collected from Niuwang island in Sanya, Hainan Province, PR China. The taxonomic position of the strain was investigated using a polyphasic approach. On the basis of 16S rRNA gene sequence analysis, strain NEAU-AAG5^T belongs to the genus Actinomadura and shared highest sequence similarity with Actinomadura macra NBRC 14102^T (98.8 %). Strain NEAU-AAG5^T grows at 20-40 °C (optimum, 28 °C), pH 6-10 (optimum, pH 7) and has NaCl tolerance of 0-3 %. The menaquinones were identified as MK-9(H₄) (4.2 %), MK-9(H₆) (49.2 %) and MK-9(H₈) (46.5 %). The major fatty acids were C_16 : 0 (31.4 %), 10-methyl C_18 : 0 (21.3 %) and C_18 : 1  ω9c (15.7 %). The polar lipids were diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositolmannoside, phosphatidylglycerol and phosphoglycolipid. The genomic DNA G+C content of strain NEAU-AAG5^T based on whole genome sequences was 72.8 mol%. Digital DNA-DNA hybridization between strain NEAU-AAG5^T and its closest phylogenetic neighbour, A. macra NBRC 14102^T, resulted in similarity value of 28.0 % (<70 %). Additionally, the average nucleotide identity was 84.2 % for A. macra NBRC 14102^T. On the basis of phenotypic, genotypic and phylogenetic data, strain NEAU-AAG5^T can be characterized to represent a novel species of the genus Actinomadura, for which the name Actinomadura litoris sp. nov. is proposed. The type strain is NEAU-AAG5^T (=JCM 33456^T=CCTCC AA 2019043^T).

Actinomadura decatromicini sp. nov., isolated from mountain soil in Thailand

A novel actinomycete strain CYP1-5T was isolated from the mountain soil sample collected from Chaiyaphum province, Thailand and its taxonomic position was clarified by using a polyphasic taxonomic approach. The chemotaxonomic properties of strain CYP1-5T were consistent within the genus Actinomadura. Cell-wall peptidoglycan of this strain contained meso-diaminopimelic acid. Galactose, madurose, and ribose were presented as the diagnostic sugars in whole-cell hydrolysates. The major menaquinone was MK-9(H6). Major cellular fatty acids were iso-C16:0 and C16:0. Phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, and phosphatidylinositol mannoside were observed as predominant phospholipids. Based on the results of phylogenetic analyses of 16S rRNA gene sequence, strain CYP1-5T was constituent with the genus Actinomadura and was closely related to Actinomadura syzygii GKU157T (99.5%) and Actinomadura chibensis IFM 10266T (= JCM 14158T) (98.2%). The draft genome size of strain CYP1-5T was 9.30 Mb with 72.2 mol% of G + C content. Strain CYP1-5T showed ANIb values of 94.9% with A. syzygii GKU157T and 93.2% with A. chibensis JCM 14158T. Phenotypic characteristics, phylogenetic analysis and genome data support that strain CYP1-5T could be discriminated from its closest relatives, representing a novel species of the genus Actinomadura, for which the name Actinomadura decatromicini sp. nov. is proposed. The type strain is CYP1-5T (= JCM 16996T = KCTC 19916T = TISTR 2901T).

Nonomuraea nitratireducens sp. nov., a new actinobacterium isolated from Suaeda australis Moq. rhizosphere

A novel actinomycete, designated WYY166T, was isolated from the rhizosphere of Suaeda australis Moq. collected in Dongfang, PR China. The taxonomic position of this strain was investigated using a polyphasic approach. Phylogenetic analysis based on its 16S rRNA gene referred strain WYY166T to the genus Nonomuraea , and it was most closely related to the type strains Nonomuraea candida HMC10T, Nonomuraea turkmeniaca DSM 43926T, Nonomuraea maritima NBRC 106687T and Nonomuraea polychroma DSM 43925T (98.35, 97.60, 97.36 and 97.30% sequence similarity, respectively). Genome sequencing revealed a genome size of 11.27 Mbp and a G+C content of 71.10 mol%. The genome average nucleotide identity (ANI) values and the digital DNA - DNA hybridization (dDDH) values between strain WYY166T and the other species of the genus were found to be low (ANI 81.63~85.23 %, dDDH 23.6~31.6 %), suggesting that it represented a new species. The physiological evaluation showed that it had remarkable nitrate reduction activity. The whole-cell hydrolysates contained meso-diaminopimelic acid and madurose. The N-acyl type of muramic acid was acetyl. The major menaquinones were MK-9 (H4) (86.9 %) and MK-9 (H2) (13.1 %). The predominant fatty acids were iso-C16 : 0 (53.2 %), 10-methyl C17 : 0 (10.7 %), C17 : 1  ω6c (8.3 %) and iso-C16 : 1 h (7.3 %). These physiological, biochemical and chemotaxonomic data suggested that strain WYY166T should be classified as representing a novel species of the genus Nonomuraea , for which the name Nonomuraea nitratireducens sp. nov. is proposed. The type strain is WYY166T (=MCCC 1K03779T=KCTC 49343T).

Description of the bacterial RNA polymerase inhibitor GE23077-producer Actinomadura sp. NRRL B-65521T as Actinomadura lepetitiana sp. nov

The filamentous actinomycete that produces the antibiotic GE23077 was isolated by the Lepetit Research Group from a soil sample collected in Thailand, and it was classified as a member of the genus Actinomadura on the basis of its morphology and cell-wall composition. Phylogenetic analysis based on 16S rRNA gene sequences indicated that this strain formed a distinct monophyletic line within the genus Actinomadura, and it was most closely related to Actinomadura bangladeshensis DSM 45347^T (99.31 % similarity) and Actinomadura mexicana DSM 44485^T (98.94 %). The GE23077-producing strain formed an extensively branched, non-fragmented vegetative mycelium; no pseudosporangia were formed and the arthrospores were organized in slightly twisted chains. The cell wall contained meso-2,6-diaminopimelic acid and the diagnostic sugar was madurose. The predominant menaquinone was MK-9(H₆), with minor amounts of MK-9(H₈) and MK-9(H₄). The diagnostic phospholipids were phosphatidylinositol and diphosphatidylglycerol. The major cellular fatty acids were C_16 : 0 and tuberculostearic acid (10-methyloctadecanoic acid), followed by minor amounts of C_18:1ω9c, C_16:1ω7c and 10-methylheptadecanoic acid. The genomic DNA G+C content was 71.77 mol%. Significant differences in the morphological, chemotaxonomic and biochemical data, and the low DNA-DNA relatedness between the GE23077-producing strain and closely related type strains clearly demonstrate that it represents a novel species of the genus Actinomadura, for which the name Actinomadura lepetitiana sp. nov. is proposed. The type strain is NRRL B-65521^T(=LMG 31258^T=DSM 109019^T).

Saccharothrix deserti sp. nov., an actinomycete isolated from desert soil

A Gram-stain-positive, aerobic actinomycete, designated strain BMP B8144^T, was isolated from desert soil, in Xinjiang province, northwest China. The isolate produced scanty aerial mycelium and fragmented substrate mycelium on most tested media. Cell-wall hydrolysates contained meso-diaminopimelic acid, galactose and mannose. The diagnostic phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylhydroxylethanolamine, phosphatidylinositol, and phosphatidylinositol mannosides. The major fatty acids included iso-C_16 : 0, C_17 : 1 ω8c and iso-C_15 : 0. The predominant menaquinones were MK-9(H₄) and MK-10(H₄). The DNA G+C content was 70.4 mol% (genome). Based on the 16S rRNA gene sequence analysis on EzBioCloud server, strain BMP B8144^T showed the closest similarities to Saccharothrix lopnurensis YIM LPA2h^T (98.9 %) and 'Saccharothrix yanglingensis' Hhs.015 (98.6 %). However, it can be distinguished from the closest strains based on the low levels of DNA-DNA relatedness (59.3±1.8 and 47.9±2.3 %, respectively). A combination of morphological, chemotaxonomic and phylogenetic characteristics, strain BMP B8144^T represents a novel species of the genus Saccharothrix, for which the name Saccharothrix deserti sp. nov. is proposed. The type strain is BMP B8144^T (=CGMCC 4.7490^T=KCTC 49001^T).

Actinomadura roseirufa sp. nov., producer of semduramicin, a polyether ionophore

The taxonomic position of 'Actinomadura roseorufa' LMG 30035^T, a semduramicin-producing mutant of strain ATCC 53666^P, which was isolated from a soil sample collected in Yamae Village, Kamamoto, Japan, was clarified in the present study using a polyphasic approach. This Gram-positive, aerobic actinomycete formed a well-developed, extensively branched, non-fragmenting substrate and aerial mycelia which differentiated into single, smooth-appearing spores. Based on analysis of nearly complete 16S rRNA gene sequence, strain LMG 30035^T was found to be closely related to the type strains of Actinomadura fibrosa ATCC 49459^T (98.88 %) and Actinomadura formosensis JCM 7474^T (98.82 %) (pairwise similarity values in parentheses). Digital DNA-DNA hybridisation experiments revealed unambiguously that strain LMG 30035^T represents a novel Actinomadura species (OrthoANIu values less than 83.1 %; dDDH values less than 27.2 % with type strains of validly named Actinomadura species). Analysis of the cell wall revealed the presence of meso-diaminopimelic acid in the peptidoglycan. The whole-cell sugars were glucose, madurose, galactose, ribose and rhamnose. The major polar lipids included phosphatidylinositol and diphosphatidylglycerol. The predominant menaquinones were MK-9(H₆), MK-9(H₈), MK-9(H₄) and MK-9(H₂). The major fatty acids were C_16 : 00, 10-methyl C_18 : 0, C_18 : 1  ω9c and C_18 : 00. The DNA G+C content of its genome was 72.5 mol%. In summary, these characteristics distinguish strain LMG 30035^T from validly named species of the genus Actinomadura, and therefore, we propose to classify this strain formally as the novel species Actinomadura roseirufa sp. nov. with LMG 30035^T (=CECT 9808^T,=ATCC 53664^T) as the type strain.

Nonomuraea mangrovi sp. nov., an actinomycete isolated from mangrove soil

A novel aerobic actinomycete, designated HA15826^T, was isolated from a mangrove soil sample collected in Sanya, China. Scanning electron microscopy revealed that the isolate produced straight to slightly flexural spore chains with rough cylindrical spores. Chemotaxonomic tests showed that the cell wall contained meso-diaminopimelic acid and the major fatty acids were iso-C16 : 0, 10-methyl-C17 : 0, C17 : 1ω8c and C16 : 0. 16S rRNA gene sequence similarity analysis showed that strain HA15826^T belonged to the genus Nonomuraea, being most closely related to Nonomuraea dietziae DSM 44320^T (98.7 %), Nonomuraea candida HMC10^T (98.4 %), Nonomuraea africana IFO 14745^T (98.4 %), Nonomuraea roseola IFO 14685^T (98.2 %) and Nonomuraea recticatena IFO 14525^T (98.1 %). The DNA G+C content of the type strain is 73.2 %. DNA-DNA relatedness and comparative analyses of physiological, biochemical and chemotaxonomic data allowed genotypic and phenotypic differentiation of strain HA15826^T from the closely related species. Thus, strain HA15826^T should be classified as a novel species of the genus Nonomuraea, for which the name Nonomuraeamangrovi sp. nov. is proposed. The type strain is HA15826^T (=CGMCC 4.7425^T=DSM 105694^T).

Genome-Based Taxonomic Classification of the Phylum Actinobacteria

The application of phylogenetic taxonomic procedures led to improvements in the classification of bacteria assigned to the phylum Actinobacteria but even so there remains a need to further clarify relationships within a taxon that encompasses organisms of agricultural, biotechnological, clinical, and ecological importance. Classification of the morphologically diverse bacteria belonging to this large phylum based on a limited number of features has proved to be difficult, not least when taxonomic decisions rested heavily on interpretation of poorly resolved 16S rRNA gene trees. Here, draft genome sequences of a large collection of actinobacterial type strains were used to infer phylogenetic trees from genome-scale data using principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families, and genera, as well as many species and a few subspecies were shown to be in need of revision leading to proposals for the recognition of 2 orders, 10 families, and 17 genera, as well as the transfer of over 100 species to other genera. In addition, emended descriptions are given for many species mainly involving the addition of data on genome size and DNA G+C content, the former can be considered to be a valuable taxonomic marker in actinobacterial systematics. Many of the incongruities detected when the results of the present study were compared with existing classifications had been recognized from 16S rRNA gene trees though whole-genome phylogenies proved to be much better resolved. The few significant incongruities found between 16S/23S rRNA and whole genome trees underline the pitfalls inherent in phylogenies based upon single gene sequences. Similarly good congruence was found between the discontinuous distribution of phenotypic properties and taxa delineated in the phylogenetic trees though diverse non-monophyletic taxa appeared to be based on the use of plesiomorphic character states as diagnostic features.

Actinomadura rhizosphaerae sp. nov., isolated from rhizosphere soil of the plant Azadirachta indica

A novel actinomycete, strain SDA37^T, belonging to the genus Actinomadura, was isolated from rhizosphere soil collected from Udon Thani Province, Thailand. The taxonomic position of the strain was characterized using a polyphasic approach. Meso-diaminopimelic acid, glucose, ribose, galactose and madurose were detected in cell-wall and whole-cell hydrolysates. The N-acyl type of muramic acid was acetyl. Menaquinones were MK-9(H6), MK-9(H8) and MK-9(H4). The predominant cellular fatty acids were iso-C16 : 0, C16 : 0, 10-methyl C18 : 0 and iso-C14 : 0. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol and phosphatidylinositol. blast analysis of the almost-complete 16S rRNA gene sequence showed 98.8 % similarity to Actinomadura oligospora NBRC 104149^T, 98.7 % similarity to Actinomadura gamaensis DSM 100815^T and 97.2 % similarity to Actinomadura rupiterrae KCTC 19559^T. The DNA G+C content was 73.1 mol%. Strain SDA37^T showed low DNA-DNA relatedness (44.3±7.3 to 58.5±8.7 %) to A. oligospora NBRC 104149^T, Actinomadura gamaensis DSM 100815^T and Actinomadura rupiterrae KCTC 19559^T. The new strain could also be distinguished from its closely related strains by the differences in the phenotypic characteristics. The results of taxonomic analysis suggested that strain SDA37^T represented a novel species of the genus Actinomadura for which the name Actinomadura rhizosphaerae sp. nov. is proposed. The type strain is SDA37^T (=KCTC 39965^T=NBRC 112909^T=TISTR 2523^T).

Actinomadura hankyongense sp. nov. Isolated From Soil of Ginseng Cultivating Field

A Gram-positive, rod-shaped, non-spore-forming, and aerobic bacterium (Gsoil 556^T) was isolated from soil of a ginseng field and subjected to its taxonomic position. Based on 16S rRNA gene sequence similarity, strain Gsoil 556^T was shown to belong to the genus Actinomadura of the family Thermomonosporaceae and was closely related to A. montaniterrae CYP1-1B^T (99.3%), A. nitritigenes DSM 44137^T (98.7%), and A. rudentiformis HMC1^T (98.5%), while it showed less than 98.4% sequence similarity to the other species of this genus. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that it is most closely related to A. rudentiformis HMC1^T and A. nitritigenes DSM 44137^T. The DNA G+C content was 73.1 mol%. The peptidoglycan was meso-diaminopimelic acid and the whole-cell sugar contained fucose, galactose, glucose, mannose, and ribose. The predominant menaquinone (KK) was MK-9(H₈) [55%] and MK-9(H₆) [45%]. The major cellular fatty acids were C_14:0, C_16:0, C_18:1 ω9c and summed feature 3 (C_16:1 ω6c/C_16:1 ω7c). All these data supported the affiliation of strain Gsoil 556^T to the genus Actinomadura. The DNA-DNA hybridization between strain Gsoil 556^T and its phylogenetically closest relatives were less than 40%. Furthermore, the results of physiological and biochemical tests enabled strain Gsoil 556^T to be differentiated genotypically and phenotypically from currently known Actinomadura species. Therefore, strain Gsoil 556^T represents a novel species of the genus Actinomadura, for which the name Actinomadura hankyongense sp. nov. is proposed. The type strain Gsoil 556^T (=KACC 19438^T=LMG 30327^T).

Actinomadura alkaliterrae sp. nov., isolated from an alkaline soil

A polyphasic study was undertaken to establish the taxonomic status of an Actinomadura strain isolated from the margin of a saline, alkaline lake in Central Anatolia, Turkey. Strain D310AT^T was shown to have chemotaxonomic, cultural and morphological properties consistent with its classification in the genus Actinomadura such as hooked or irregular spiral spore chains, meso-diaminopimelic acid as the major cell wall diaminopimelic acid, and diphosphatidylglycerol and phosphatidylinositol as major polar lipids. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain D310AT^T is closely, albeit loosely, associated with Actinomadura darangshiensis DLS-70^T with 97.2% sequence similarity, but was readily separated from the latter using diverse phenotypic properties. Consequently, the isolate is considered to represent a new species of Actinomadura for which the name Actinomadura alkaliterrae sp. nov. is proposed, with the type strain D310AT^T (=DSM 101185^T = KCTC 39657^T).

Classification of Nonomuraea sp. ATCC 39727, an actinomycete that produces the glycopeptide antibiotic A40926, as Nonomuraea gerenzanensis sp. nov

Strain ATCC 39727, which produces the antibiotic A40926 (the natural precursor of the antibiotic dalbavancin), was isolated from a soil sample collected in India, and it was originally classified as a member of the genus Actinomadura on the base of morphology and cell-wall composition. A phylogenetic analysis based on 16S rRNA gene sequences indicates that the strain forms a distinct clade within the genus Nonomuraea, and it is most closely related to Nonomuraea angiospora DSM 43173T (98.72 % similarity) and Nonomuraea jabiensis A4036T (98.69 %). The strain forms an extensively branched substrate mycelium and aerial hyphae that form spiral chains of spores with ridged surfaces. The cell wall contains meso-diaminopimelic acid and the whole-cell sugars are glucose, ribose, galactose, mannose and madurose (madurose as the diagnostic sugar). The N-acyl type of muramic acid is acetyl. The predominant menaquinone is MK-9(H4), with minor amounts of MK-9(H2), MK-9(H6) and MK-9(H0). The polar-lipid profile includes diphosphatidylglycerol, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylmethylethanolamine, hydroxyphosphatidylmethylethanolamine, phosphatidylinositol and a series of uncharacterized phospholipids, glycolipids and phosphoglycolipids. The major cellular fatty acids are iso-C16 : 0 and 10-methyl C17 : 0. The genomic DNA G+C content is 71.2 mol%. Significant differences in the morphological, chemotaxonomic and biochemical data, together with DNA-DNA relatedness between strain ATCC 39727 and closely related type strains, clearly demonstrated that strain ATCC 39727 represents a novel species of the genus Nonomuraea, for which the name Nonomuraea gerenzanensis sp. nov. is proposed. The type strain is ATCC 39727T ( = DSM 100948T).

Actinomadura Species: Laboratory Maintenance and Ribosome Engineering

Actinomadura spp. are aerobic, Gram-positive, catalase-positive, non-acid fast, non-motile actinomycetes. Some species of Actinomadura are associated with opportunistic infections in humans. However, many bioactive compounds with pharmaceutical applications can be isolated from various Actinomadura spp. This unit includes general protocols for the laboratory maintenance of Actinomadura spp., including growth in liquid medium, growth on solid agar, long-term storage, and generation of a higher producing strain by ribosome engineering. Actinomadura hibisca P157-2 is used as a prototype for explaining the considerations for efficient laboratory maintenance of Actinomadura spp. © 2017 by John Wiley & Sons, Inc.

Actinomadura adrarensis sp. nov., an actinobacterium isolated from Saharan soil

A novel actinobacterial strain, designated ACD12^T, was isolated from a Saharan soil sample collected from Adrar province, southern Algeria. A polyphasic study was carried out to establish the taxonomic position of this strain. Strain ACD12^T was observed to form extensively branched substrate mycelia. Aerial mycelium was absent or was weakly produced on all media tested, while spore chains were short with a hooked and irregular spiral form (2-3 turns). The dominant diaminopimelic acid isomer in the cell wall was meso-diaminopimelic acid. Glucose, ribose, galactose, mannose and madurose occured in whole-cell hydrolysates. The major phospholipid was diphosphatidylglycerol and phosphatidylinositol. The predominant menaquinone was MK-9(H6). The fatty acid profile was characterized by the presence of C16 : 0, C17 : 0, C15 : 0, C18 : 0, C18 : 1 cis9 and iso-C16 : 0. Results of 16S rRNA gene sequence comparisons revealed that strain ACD12^T shared the highest degree of 16S rRNA gene sequence similarity with Actinomadura sputi DSM 45233^T (98.3 %) and Actinomadura hallensis DSM 45043^T (97.8 %). All tree-making algorithms used also supported strain ACD12^T forming a distinct clade with its most closely related species. In addition, DNA-DNA hybridization indicated only 39.8 % relatedness with A. sputi DSM 45233^T and 18.7 % relatedness with A. hallensis DSM 45043^T. The combined phenotypic and genotypic data show that the novel isolate represents a novel species of the genus Actinomadura, for which the name Actinomadura adrarensis sp. nov., is proposed, with the type strain ACD12^T (=DSM 46745^T =CECT 8842^T).

Taxonomy, Physiology, and Natural Products of Actinobacteria

Actinobacteria are Gram-positive bacteria with high G+C DNA content that constitute one of the largest bacterial phyla, and they are ubiquitously distributed in both aquatic and terrestrial ecosystems. Many Actinobacteria have a mycelial lifestyle and undergo complex morphological differentiation. They also have an extensive secondary metabolism and produce about two-thirds of all naturally derived antibiotics in current clinical use, as well as many anticancer, anthelmintic, and antifungal compounds. Consequently, these bacteria are of major importance for biotechnology, medicine, and agriculture. Actinobacteria play diverse roles in their associations with various higher organisms, since their members have adopted different lifestyles, and the phylum includes pathogens (notably, species of Corynebacterium, Mycobacterium, Nocardia, Propionibacterium, and Tropheryma), soil inhabitants (e.g., Micromonospora and Streptomyces species), plant commensals (e.g., Frankia spp.), and gastrointestinal commensals (Bifidobacterium spp.). Actinobacteria also play an important role as symbionts and as pathogens in plant-associated microbial communities. This review presents an update on the biology of this important bacterial phylum.

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

A novel thermotolerant actinomycete, designated strain 3-33-9B^T, 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 3-33-9B^T 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-C_16 : 0 and C_17 : 0. The quinone system was predominantly composed of MK-9(H₄). The DNA G+C content of strain 3-33-9B^T 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 3-33-9B^T formed a distinct phyletic line and was most closely related to Nonomuraea fastidiosa NBRC 14680^T (97.3 % 16S rRNA gene sequence similarity). However, phenotypic characteristics of strain 3-33-9B^T were significantly different from N. fastidiosa NBRC 14680^T, and DNA-DNA hybridization showed little relatedness (31.6-35.2 %) between the two strains. Based on the phenotypic and phylogenetic data, strain 3-33-9B^T represents a novel species of the genus Nonomuraea, for which the name Nonomuraea thermotolerans sp. nov. is proposed. The type strain is 3-33-9B^T ( = ATCC BAA-2629^T = CGMCC 4.7161^T).

Actinomadura algeriensis sp. nov., an actinobacterium isolated from Saharan soil

During the course of a screening programme for new taxa of actinobacteria, a strain designated ACD1(T), was isolated from a Saharan soil in the Hoggar region (Algeria). The taxonomic position of this strain was determined using a polyphasic taxonomic approach. The strain was observed to form extensively branched, non-fragmenting substrate mycelium, and aerial mycelium with straight to flexuous, hooked and irregular spirals (1-2 turns) forming short chains of spores. The diamino acid present in the cell wall is meso-diaminopimelic acid. Galactose, glucose, madurose, mannose and ribose occur in whole-cell hydrolysates. The diagnostic phospholipids detected were diphosphatidylglycerol and phosphatidylinositol. The major menaquinones were identified as MK-9 (H4) and MK-9 (H2). The major fatty acids were found to be C16:0, C18:1 cis9, iso-C16:0 and 10-methyl C18:0. Phylogenetic analysis based on the 16S rRNA gene showed that the strain belongs to the genus Actinomadura, and is closely related to Actinomadura sediminis DSM 45500(T) (98.5 % similarity) and Actinomadura cremea subsp. cremea DSM 43676(T) (98.3 % similarity). However, DNA-DNA hybridization revealed only 48.0 % relatedness with A. sediminis DSM 45500(T) and 33.2 % relatedness with A. cremea subsp. cremea DSM 43676(T). The combined phenotypic and genotypic data showed that the strain represents a novel species of the genus Actinomadura, for which the name Actinomadura algeriensis sp. nov. is proposed, with the type strain ACD1(T) (= DSM 46744(T) = CECT 8841(T)).

Thermophilic and alkaliphilic Actinobacteria: biology and potential applications

Microbes belonging to the phylum Actinobacteria are prolific sources of antibiotics, clinically useful bioactive compounds and industrially important enzymes. The focus of the current review is on the diversity and potential applications of thermophilic and alkaliphilic actinobacteria, which are highly diverse in their taxonomy and morphology with a variety of adaptations for surviving and thriving in hostile environments. The specific metabolic pathways in these actinobacteria are activated for elaborating pharmaceutically, agriculturally, and biotechnologically relevant biomolecules/bioactive compounds, which find multifarious applications.

The genus Nonomuraea: A review of a rare actinomycete taxon for novel metabolites

The genus Nonomuraea is a rare actinomycete taxon with a long taxonomic history, while its generic description was recently emended. The genus is less known among the rare actinomycete genera as its taxonomic position was revised several times. It can be found in diverse ecological niches, while most of its member species were isolated from soil samples. However, new trends to discover the genus in other habitats are increasing. Generic abundance of the genus was found to be dependent on geographical changes. Novel sources together with selective and invented isolation techniques might increase a chance to explore the genus and its novel candidates. Interestingly, some of its members have been revealed as a valuable source of novel metabolites for medical and industrial purposes. Broad-range of potent bioactive compounds including antimicrobial, anticancer, and antipsychotic substances, broad-spectrum antibiotics and biocatalysts can be synthesized by the genus. In order to investigate biosynthetic pathways of the bioactive compounds and self-resistant mechanisms to these compounds, the links from genes to metabolites have yet been needed for further discovery and biotechnological development of the genus Nonomuraea.

Nonomuraea guangzhouensis sp. nov., and Nonomuraea harbinensis sp. nov., two novel actinomycetes isolated from soil

Two novel actinomycetes, designated strains NEAU-ZJ3(T) and NEAU-yn31(T), were isolated from soils in China and their taxonomic positions determined by a polyphasic approach. Key morphological and chemotaxonomic properties of the two strains were consistent with the description of the genus Nonomuraea. The G+C contents of strains NEAU-ZJ3(T) and NEAU-yn31(T) were determined to be 67.4 and 68.0 %, respectively. Phylogenetic analysis using 16S rRNA gene sequences indicated that the two strains should be classified in the genus Nonomuraea. The 16S rRNA gene sequence of strain NEAU-ZJ3(T) showed it to be most closely related to Nonomuraea salmonea DSM 43678(T) (98.27 %), Nonomuraea endophytica YIM 65601(T) (98.23 %) and Nonomuraea candida HMC10(T) (98.08 %), and that of strain NEAU-yn31(T) to Nonomuraea ferruginea IFO 14094(T) (99.08 %) and N. candida HMC10(T) (98.01 %). Furthermore, a combination of DNA-DNA hybridization results and some phenotypic characteristics indicated that the two strains can be distinguished from each other and their phylogenetically closest relatives. Thus, strains NEAU-ZJ3(T) and NEAU-yn31(T) represent two novel species of the genus Nonomuraea, for which the names Nonomuraea guangzhouensis sp. nov. and Nonomuraea harbinensis sp. nov. are proposed. The type strains are NEAU-ZJ3(T) (=CGMCC 4.7101(T) = DSM 45889(T)) and NEAU-yn31(T) (=CGMCC 4.7106(T) = DSM 45887(T)), respectively.

Microbispora hainanensis sp. nov., isolated from rhizosphere soil of Excoecaria agallocha in a mangrove

Strain 211020T was isolated from rhizosphere soil of Excoecaria agallocha in a mangrove in Hainan, China. The strain produced longitudinal pair spores branching from aerial hyphae. 16S rRNA gene sequence analysis showed that the isolate belonged to the genus Microbispora , exhibiting the highest 16S rRNA gene sequence similarity (98.75 %) to Microbispora corallina JCM 10267T with a low DNA–DNA relatedness value (13±0.6 %). The isolate contained meso-diaminopimelic acid as the diagnostic diamino acid but madurose was not detected. The predominant menaquinones were MK-9(H4), MK-9(H2) and MK-9(H0), and the major fatty acids were iso-C16 : 0, iso-C15 : 0 and C17 : 0. The phospholipid profile of strain 211020T comprised phosphatidylinositol mannoside, phosphatidylethanolamine, diphosphatidylglycerol and phospholipids of unknown structure containing glucosamine. The DNA G+C content was 70.8 mol%. On the basis of phenotypic and genotypic data, strain 211020T can be distinguished as a novel species of the genus Microbispora , for which the name Microbispora hainanensis sp. nov., is proposed. The type strain is 211020T ( = CGMCC 4.5595T = DSM 45428T).

Actinomadura geliboluensis sp. nov., isolated from soil

A novel actinobacterium, strain A8036T, isolated from soil, was investigated by using a polyphasic taxonomic approach. The organism formed extensively branched substrate hyphae that generated spiral chains of spores with irregular surfaces. The cell wall contained meso-diaminopimelic acid (type III) and cell-wall sugars were glucose, madurose, mannose and ribose. The predominant menaquinones were MK-9(H6) and MK-9(H4). The phospholipids were diphosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides. The major cellular fatty acids were iso-C16 : 0, C17 : 1 cis9, C16 : 0, C15 : 0 and 10-methyl C17 : 0. Based on 16S rRNA gene sequence analysis, the closest phylogenetic neighbours of strain A8036T were Actinomadura meyerae DSM 44715T (99.23 % similarity), Actinomadura bangladeshensis DSM 45347T (98.9 %) and Actinomadura chokoriensis DSM 45346T (98.3 %). However, DNA–DNA relatedness and phenotypic data demonstrated that strain A8036T could be clearly distinguished from the type strains of all closely related Actinomadura species. Strain A8036T is therefore considered to represent a novel species of the genus Actinomadura , for which the name Actinomadura geliboluensis sp. nov. is proposed. The type strain is A8036T ( = DSM 45508T = KCTC 19868T).

Actinomadura sediminis sp. nov., a marine actinomycete isolated from mangrove sediment

In this study, the taxonomic position of an actinobacterium, strain YIM M 10931T, which was isolated from a mangrove sediment sample collected in Dugong Creek, Little Andaman, India, was determined by a polyphasic approach. This Gram-positive, aerobic strain produced branched substrate mycelium and aerial hyphae, which differentiated into short, hooked or spiral spore chains. The organism contained meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan. The whole cell sugars consisted of mannose, ribose, glucose, galactose and madurose. The cellular fatty acid profile mainly consisted of iso-C16 : 0, 10-methyl C18 : 0 and C16 : 0. The quinone system was predominantly composed of MK-9(H8) (45.5 %) and MK-9(H6) (39 %). The phospholipids detected were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol and two unknown phospholipids. The organism showed a combination of morphological and chemotaxonomic properties typical of members of the genus Actinomadura . Moreover, phylogenetic analysis based on a 16S rRNA gene sequence generated from the strain identified its closest relatives as Actinomadura cremea DSM 43676T (98.4 % sequence similarity), Actinomadura rifamycini DSM 43936T (97.4 %) and Actinomadura apis IM17-1T (96.9 %). It was obvious from the resulting phylogenetic trees that strain YIM M 10931T belongs to a distinct subclade within the evolutionary radiation of the genus Actinomadura . DNA–DNA hybridizations of strain YIM M 10931T with A. cremea DSM 43676T and A. rifamycini DSM 43936T were performed and further confirmed that the isolate represents a separate genomic species. Based on the phenotypic and genotypic characteristics presented, it is proposed that strain YIM M 10931T represents a novel species within the genus Actinomadura , for which the name Actinomadura sediminis sp. nov. is proposed; the type strain is YIM M 10931T ( = CCTCC AA 2010009T = DSM 45500T).

Nonomuraea monospora sp. nov., an actinomycete isolated from cave soil in Thailand, and emended description of the genus Nonomuraea

A novel actinomycete, designated strain PT708(T), was isolated from cave soil collected in Pha Tup Cave Forest Park, Nan province, Thailand. It produced compounds with antimicrobial and anticancer activities. Its chemotaxonomic properties were consistent with those of members of the genus Nonomuraea. The major menaquinone was MK-9(H(4)), with minor amounts of MK-9(H(6)), MK-9(H(2)), MK-10(H(2)) and MK-8(H(4)). The polar lipid profile contained phosphatidylmonomethylethanolamine, diphosphatidylglycerol, hydroxy-phosphatidylmonomethylethanolamine, hydroxy-phosphatidylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol mannoside and phosphatidylinositol. The major fatty acids were iso-C(16:0), 10-methyl C(17:0), C(16:0) and C(17:1)ω6c. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain PT708(T) belonged to the genus Nonomuraea and was most closely related to Nonomuraea rhizophila YIM 67092(T) (98.50% sequence similarity) and Nonomuraea rosea GW 12687(T) (98.30%). The genomic DNA G+C content of strain PT708(T) was 73.3 mol%. Unlike the recognized members of the genus Nonomuraea, the novel strain formed single spores at the tips of aerial hyphae. Based on the phenotypic, phylogenetic and genotypic evidence, strain PT708(T) represents a novel species of the genus Nonomuraea, for which the name Nonomuraea monospora sp. nov. is proposed. The type strain is PT708(T) ( = TISTR 1910(T) = JCM 16114(T)).

Taxonomy, purification and chemical characterization of four bioactive compounds from new Streptomyces sp. TN256 strain

A new actinomycete strain designated TN256, producing antimicrobial activity against pathogenic bacteria and fungi, was isolated from a Tunisian Saharan soil. Morphological and chemical studies indicated that strain TN256 belonged to the genus Streptomyces. Analysis of the 16S rDNA sequence of strain TN256 showed a similarity level ranging between 99.79 and 97.8% within Streptomyces microflavus DSM 40331(T) and Streptomyces griseorubiginosus DSM 40469(T) respectively. The comparison of its physiological characteristics showed significant differences with the nearest species. Combined analysis of the 16 S rRNA gene sequences (FN687758), fatty acids profile, and results of physiological and biochemical tests indicated that there were genotypic and phenotypic differentiations of that isolate from other Streptomyces species neighbours. These date strongly suggest that strain TN256 represents a novel species with the type strain Streptomyces TN256 (=CTM50228(T)). Experimental validation by DNA-DNA hybridization would be required for conclusive confirmation. Four active products (1-4) were isolated from the culture broth of Streptomyces TN256 using various separation and purification steps and procedures. 1: N-[2-(1H-indol-3-yl)-2 oxo-ethyl] acetamide 'alkaloid' derivative; 2: di-(2-ethylhexyl) phthalate, a phthalate derivative; 3: 1-Nonadecene and 4: Cyclo (L: -Pro-L: -Tyr) a diketopiperazine 'DKP' derivative. The chemical structure of these four active compounds was established on the basis of spectroscopic studies NMR and by comparing with data from the literature. According to our biological studies, we showed in this work that the pure compounds (1-4) possess antibacterial and antifungal activities.

Actinomadura apis sp. nov., isolated from a honey bee (Apis mellifera) hive, and the reclassification of Actinomadura cremea subsp. rifamycini Gauze et al. 1987 as Actinomadura rifamycini (Gauze et al. 1987) sp. nov., comb. nov

A Gram-reaction-positive aerobic actinomycete, designated strain IM17-1(T), was isolated from a honey bee (Apis mellifera) hive in Chiang Mai Province, Thailand. The strain formed a branched substrate mycelium and mature aerial mycelium bore short chains of arthrospores with warty surfaces. The cell wall contained meso-2,6-diaminopimelic acid (cell-wall type III) and the whole cell sugars were fucose, galactose, glucose, madurose, mannose and ribose. The major isoprenoid quinone was hexahydrogenated menaquinone with nine isoprene units and the predominant cellular fatty acids were C₁₆:₀ (33.8 %), C₁₈:₁ω9c (32.7 %), summed feature 3 (C₁₆:₁ω7c and/or iso-C₁₅:₀ 2-OH) (8.7 %) and 10-methyl C₁₈:₀ (8.2 %). The phospholipids were diphosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides. These morphological and chemotaxonomic characteristics were consistent with the classification of IM17-1(T) within the genus Actinomadura. Based on 16S rRNA gene sequence analysis, strain IM17-1(T) was closely related to the type strains of Actinomadura cremea subsp. cremea (98.1 %) and Actinomadura cremea subsp. rifamycini (98.6 %); however, it represented a distinct phylogenetic lineage from the other species within this genus. The unique genetic characteristics were reaffirmed by low levels of DNA-DNA relatedness between strain IM17-1(T) and the two most closely related type strains, A. cremea subsp. cremea JCM 3308(T) (56.5±4.9 %) and A. cremea subsp. rifamycini JCM 3309(T) (31.0±22.6 %), and further supported the proposal of IM17-1(T) as a novel species. Strain IM17-1(T) ( = JCM 16576(T)  = TISTR 1980(T)) thus represents a novel species of the genus Actinomadura, for which the name Actinomadura apis sp. nov. is proposed. In addition, the genotypic and phenotypic data suggested the reclassification of Actinomadura cremea subsp. rifamycini Gauze et al. 1987 as a separate species, Actinomadura rifamycini sp. nov., comb. nov.

Nonomuraea rosea sp. nov

A Gram-positively staining, aerobic, non-motile actinomycete, strain GW 12687T, that formed rose-pigmented colonies and branched substrate and aerial mycelia was studied in detail for its taxonomic position. On the basis of 16S rRNA gene sequence similarity studies, strain GW 12687T was grouped into the genus Nonomuraea, being most closely related to Nonomuraea dietziae (97.6 %), Nonomuraea africana (97.1 %), and Nonomuraea kuesteri (97.1 %). The 16S rRNA gene sequence similarity to other species of the genus Nonomuraea was ≤97 %. The chemotaxonomic characterization supported allocation of the strain to the genus Nonomuraea. The major menaquinone was MK-9(H4) with minor amounts of MK-9(H2), MK-9(H6), MK-9(H0) and MK-8(H4). The polar lipid profile contained the major compound diphosphatidylglycerol, moderate amounts of phosphatidylmonomethylethanolamine, phosphatidylethanolamine, hydroxy-phosphatidylethanolamine, hydroxy-phosphatidylmonomethylethanolamine, and an unknown aminophosphoglycolipid. Phosphatidylinositol mannosides and phosphatidylinositol were also present. The major fatty acids were iso- and anteiso- and 10-methyl-branched fatty acids. The results of physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain GW 12687T from closely related species. Thus, GW 12687T represents a novel species of the genus Nonomuraea, for which the name Nonomuraea rosea sp. nov. is proposed, with GW 12687T (=DSM 45177T =CCUG 56107T) as the type strain.

Notes on the characterization of prokaryote strains for taxonomic purposes

Taxonomy relies on three key elements: characterization, classification and nomenclature. All three elements are dynamic fields, but each step depends on the one which precedes it. Thus, the nomenclature of a group of organisms depends on the way they are classified, and the classification (among other elements) depends on the information gathered as a result of characterization. While nomenclature is governed by the Bacteriological Code, the classification and characterization of prokaryotes is an area that is not formally regulated and one in which numerous changes have taken place in the last 50 years. The purpose of the present article is to outline the key elements in the way that prokaryotes are characterized, with a view to providing an overview of some of the pitfalls commonly encountered in taxonomic papers.

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)).

Nonomuraea maheshkhaliensis sp. nov., a novel actinomycete isolated from mangrove rhizosphere mud

A strain of Nonomuraea was isolated from Maheshkhali, Cox's Bazar, an unexplored region of Bangladesh. Strain 16-5-14(T) is a Gram-positive, aerobic, non-motile actinomycete that formed branched substrate and aerial mycelia. On the basis of 16S rRNA gene sequence similarity studies, strain 16-5-14(T) was shown to belong to the genus Nonomuraea, being most closely related to Nonomuraea kuesteri. Chemotaxonomic data supported allocation of the strain as a member of the genus Nonomuraea. The strain 16-5-14(T) contained MK-9(H(4)) as the major menaquinone, the polar lipid was phosphatidylethanolamine and major cellular fatty acids were observed as C(16 : 0 )(15.5%), iso-C(16 : 0) (13.8%) and 10-methyl C(17 : 0) (9.6%). Results of DNA-DNA hybridization and physiological tests allowed genotypic and phenotypic differentiation of strain 16-5-14(T) from closely related species N. kuesteri. Thus 16-5-14(T) represents a novel species of the genus Nonomuraea. On the basis of evaluation of the morphological, physiological and chemotaxonomic characteristics, 16S rRNA gene sequence comparisons and DNA-DNA hybridization, Nonomuraea maheshkhaliensis sp. nov. (type strain, 16-5-14(T)=JCM 13929(T)=MTCC 8545(T)) is proposed.

Nonomuraea bangladeshensis sp. nov. and Nonomuraea coxensis sp. nov

Two novel bacterial strains were isolated from sandy soil from Cox's Bazar, Bangladesh. Strains 5-10-10(T) and 5-38-42(T) were Gram-positive, aerobic, non-motile actinomycetes that form branched substrate and aerial mycelium. On the basis of 16S rRNA gene sequence similarity studies, the novel strains were shown to belong to the genus Nonomuraea, being most closely related to Nonomuraea fastidiosa. Chemotaxonomic data supported the assignment of the novel strains as members of the genus Nonomuraea. Strain 5-10-10(T) contained MK-9(H(4)) and strain 5-38-42(T) contained MK-9(H(6)) and MK-9(H(4)) as the major menaquinones. Major polar lipids were phosphatidylethanolamine and hydroxyphosphatidylethanolamine. The major cellular fatty acid for strain 5-10-10(T) was iso-C(16 : 0) (26.4 %); C(16 : 0) (17.4 %) was the major cellular fatty acid for strain 5-38-42(T). The results of DNA-DNA hybridization and physiological tests enabled strains 5-10-10(T) and 5-38-42(T) to be differentiated genotypically and phenotypically from each other and from the closely related species, N. fastidiosa. On the basis of these results, strains 5-10-10(T) and 5-38-42(T) represent two novel species of the genus Nonomuraea. Following an evaluation of morphological, physiological and chemotaxonomic characteristics, 16S rRNA gene sequence comparisons and DNA-DNA hybridization experiments, the new isolates are proposed as two novel species, Nonomuraea bangladeshensis sp. nov. [type strain, 5-10-10(T) (=MTCC 8089(T)=JCM 13930(T))] and Nonomuraea coxensis sp. nov. [type strain, 5-38-42(T) (=MTCC 8090(T)=JCM 13931(T))].

Actinomadura alba sp. nov., isolated from soil in Yunnan, China

A novel actinomycete, strain YIM 45681T, which was isolated from soil in a suburb of Kunming, Yunnan Province, China, was subjected to phenotypic and genotypic characterization. The micro-organism, which produces short spore chains arranged in spirals on the aerial mycelium, was shown to have meso-diaminopimelic acid in the cell wall. The sugars present in whole-cell hydrolysates were ribose, xylose, galactose, madurose and glucose. The predominant menaquinones were MK-9(H4), MK-9(H6) and MK-9(H2). The phospholipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside. The major fatty acids were iso-C16 : 1 H, C17 : 1 ω8c, 10-methyl C17 : 0 and C16 : 0. A comparative analysis of 16S rRNA gene sequences indicated that the organism formed a distinct clade within the evolutionary radiation of the family Thermomonosporaceae, and that it was closely associated with members of the genus Actinomadura. A broad range of phenotypic and genetic data supported the suggestion that this organism represents a novel species of the genus Actinomadura, for which the name Actinomadura alba sp. nov. is proposed, with YIM 45681T (=DSM 45045T =CCTCC AA206005T) as the type strain.