Streptomyces pyxinae sp. nov. and Streptomyces pyxinicus sp. nov. isolated from lichen Pyxine cocoes (Sw.) Nyl.

Two novel actinobacteria, designated as LP05-1T and LP11T, were isolated from the lichen Pyxine cocoes (Sw.) Nyl. collected in Bangkok, Thailand. Genotypic and phenotypic analyses revealed that both strains represented members of the genus Streptomyces. The 16S rRNA gene of LP05-1T showed the highest similarity to the genome of Streptomyces gelaticus (98.41 %), while the 16S rRNA gene of LP11T was most similar to that of Streptomyces cinerochromogenes (98.93 %). The major menaquinones in LP05-1T were MK-9(H8), MK-9(H6), MK-9(H4) and MK-9(H2), and in LP11T, they were MK-9(H8) and MK-9(H6). Both strains exhibited the major fatty acids iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0, with LP05-1T also possessing iso-C17 : 0. The polar lipids of LP05-1T included phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified lipid, while those of LP11T consisted of phosphatidylethanolamine, lyso-phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, an unidentified aminolipid and an unidentified glycolipid. The digital DNA-DNA hybridisation (dDDH) and average nucleotide identity (ANI) values indicated that both strains are distinct from each other with values below 70 and 95 %, respectively. dDDH, ANI by blast (ANIb) and ANI by MUMmer (ANIm) values between LP05-1T and its closely related type strains were 26.07-26.80 %, 81.24-82.01 % and 86.82-86.96 %, respectively, while those for LP11T and its closely related type strains were 30.70-31.70 %, 84.09-85.31 % and 88.02-88.39 %, respectively. The results of the taxonomic investigation, including dDDH and ANI values, indicate that LP05-1T and LP11T are novel type strains of two novel species within the genus Streptomyces. The names proposed are Streptomyces pyxinae sp. nov. for strain LP05-1T (=TBRC 15494T, =NBRC 115434T) and Streptomyces pyxinicus sp. nov. for strain LP11T (=TBRC 15493T, =NBRC 115421T).

Actinoplanes pyxinae sp. nov., a new lichen-derived rare actinobacterium exhibiting antimicrobial and anticancer activity.

A novel lichen-derived actinobacterium, designated Pm04-4T, was isolated from Pyxine cocoes (Sw.) Nyl. lichen collected from Chaiyaphum, Thailand. A polyphasic approach was used to describe the taxonomic position of the strain. The strain had morphological and chemotaxonomic properties similar to members of the genus Actinoplanes. It produced sporangia on the substrate mycelia. Meso-diaminopimelic acid, galactose, glucose and mannose were detected in the whole-cell hydrolysate of the strain. The major menaquinone was MK-9(H4). The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside. The predominant cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. Strain Pm04-4T showed the highest 16S rRNA gene sequence similarity to Actinoplanes akusuensis TRM 8003T (99.0 %). In the phylogenomic tree, strain Pm04-4T was positioned close to A. aksuensis TRM88003T, A. maris M416T, A. polyasparticus TRM66264T, A. hotanensis TRM88002T, A. abujensis DSM 45518T, A. bogorensis NBRC 110975T, A. brasiliensis DSM 43805T, A. lichenicola LDG1-01T and A. ovalisporus LDG1-06T. The average nucleotide identity and digital DNA-DNA hybridization values between strain Pm04-4T and its closely related neighbours were below the threshold values for describing new species. Moreover, the strain could be distinguished from its closely related type strains by phenotypic properties. Based on genotypic and phenotypic evidence, it can be concluded that strain Pm04-4T is a representative of a new Actinoplanes species for which the name Actinoplanes pyxinae sp. nov. is proposed. The type strain is Pm04-4T (=TBRC 16207T=NBRC 115836T). The type strain exhibited activity against Staphylococcus aureus ATCC 25923 as well as four yeast strains, namely Candida albicans TISTR 5554, Candida glabrata TISTR 5006, Candida krusei TISTR 5351 and Candida parapsilosis TISTR 5007. It also showed cytotoxicity against Caco-2, MNT-1 and MCF-7 cancer cells.

Streptomyces rugosispiralis sp. nov., a Novel Actinobacterium Isolated from Peat Swamp Forest Soil That Produces Ansamycin Derivatives and Nocardamines.

Actinomycetes, especially the genus Streptomyces, are one of the most promising sources of bioactive natural products. In this study, a novel Streptomyces strain, RCU-064T, was isolated from a soil sample collected from a peat swamp forest in Thailand. Strain RCU-064T showed the highest 16S rRNA gene sequence similarity (99.06%) with Streptomyces malaysiensis NBRC 16446T. Based on a polyphasic approach, strain RCU-064T represents a novel species of the genus Streptomyces, for which the name Streptomyces rugosispiralis sp. nov. is proposed. The chemical isolation of the crude ethyl acetate extracts of the strain led to the isolation of six compounds: (1) geldanamycin, (2) 17-O-demethylgeldanamycin, (3) reblastatin, (4) 17-demethoxyreblastatin, (5) nocardamine, and (6) dehydroxynocardamine. These compounds were evaluated for their biological activities. All compounds showed no antimicrobial activity against tested microorganisms used in this study. Compounds (1)-(4) displayed cytotoxic activity against the NCI-H187 cell line, with IC50 values ranging from 0.045-4.250 µg/mL. Cytotoxicity against the MCF-7 cell line was found in compounds (1) and (3) with IC50 values of 3.51 and 1.27 µg/mL, respectively. Compounds (5) and (6) exhibited cytotoxicity only against Vero cells (IC50 of 16.57 µg/mL) and NCI-H187 cells (IC50 of 13.96 µg/mL), respectively. These results indicate that peat swamp forest soil remains a promising reservoir of novel actinomycetes capable of producing bioactive natural products.

Streptomyces cylindrosporus sp. nov. and Streptomyces spinosisporus sp. nov.: two new endophytic actinobacteria isolated from the roots of Barleria lupulina Lindl.

Two endophytic actinobacteria, designated as strains 7R015T and 7R016T, were isolated from the roots of Barleria lupulina collected in Thailand. The morphological characteristics and results of chemotaxonomic studies and 16S rRNA gene analysis indicated that both strains represented members of the genus Streptomyces. They contained ll-diaminopimelic acid in the peptidoglycan. Ribose and glucose were detected as the whole-cell sugars. MK-9(H4), MK-9(H6) and MK-9(H8), were found as the membrane menaquinone. The predominant cellular fatty acids detected were iso-C16 : 0 and anteiso-C15 : 0. The genomes of both strains harboured biosynthetic gene clusters for melanin, terpene, lanthipeptide, polyketides, non-ribosomal peptide synthetase, siderophore and ectoine. The 16S rRNA gene sequence of 7R015T showed the highest similarity to that of Streptomyces pseudovenezuelae DSM 40212T (98.6 %), Streptomyces cyaneus NRRL B2296T (98.6 %) and Streptomyces curacoi DSM 40107T (98.6 %). Strain 7R016T showed the highest 16S rRNA gene sequence similarity to Streptomyces gilvifuscus NBRC 110904T (98.2 %), which is lower than the threshold value for 16S rRNA gene sequence similarity for differentiation at the species level (98.65 %). Comparative genome analysis revealed that the genomes of 7R015T, 7R016T and the closely related type strains had an average nucleotide identity (ANI) of less than 95 % and a digital DNA-DNA hybridisation (dDDH) of less than 70 %, the thresholds for species demarcation. On the basis of the results of the polyphasic study, strains 7R015T and 7R016T represent novel species of the genus Streptomyces and are named herein as Streptomyces cylindrosporus sp. nov. (=NBRC 115200T = TBRC 14542T) for strain 7R015T and Streptomyces spinosisporus sp. nov. (=NBRC 115201T = TBRC 14543T) for strain 7R016T.

Streptomyces macrolidinus sp. nov., a novel soil actinobacterium with potential anticancer and antimalarial activity.

A novel actinomycete, strain RY43-2T, belonging to the genus Streptomyces, was isolated from a peat swamp forest soil collected from Rayong Province, Thailand. The strain was characterized by using a polyphasic approach. The cell-wall peptidoglycan contained ll-diaminopimelic. Ribose and glucose were detected in its whole-cell hydrolysates. The strain contained anteiso-C15:0, iso-C14:0 and iso-C16:0 as the predominant fatty acids, and MK-9(H4), MK-9(H6) and MK-9(H8) as the major menaquinones. The phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, three unidentified ninhydrin-positive phospholipids and two unidentified phospholipids. Strain RY43-2T showed the highest 16S rRNA gene similarity to Streptomyces misionensis JCM 4497T (98.9 %) and Streptomyces lichenis LCR6-01T (98.9 %). The draft genome of RY43-2T was 6.7 Mb with 6078 coding sequences with an average G+C content of 70.8 mol%. Genomic analysis revealed that the average nucleotide identity (ANI) values based on blast (ANIb) and MUMmer (ANIm) between strain RY43-2T and S. misionensis JCM 4497T were 80.1 and 86.1%, respectively. The ANIb and ANIm values between strain RY43-2T and S. lichenis LCR6-01T were 77.0 and 85.5%, respectively. The digital DNA-DNA hybridization values were 25.2 and 23.0% in comparison with the draft genomes of S. misionensis JCM 4497T and S. lichenis LCR6-01T, respectively. The results of taxonomic analysis suggested that strain RY43-2T represented a novel species of the genus Streptomyces for which the name Streptomyces macrolidinus sp. nov. is proposed. The type strain is RY43-2T (=TBRC 7286T=NBRC 115640T). Strain RY43-2T exhibited antimicrobial activity against Enterococcus faecium ATCC 51559, Colletotrichum capsici BMGC 106 and Colletotrichum gloeosporioides BMGC 107 with the minimum inhibitory concentration values of 25.0, 12.5, and 6.25 µg ml-1. It also exhibited potent antimalarial activity against Plasmodium falciparum K1 with IC50 of 0.0031 µg ml-1. In addition, it showed cytotoxicity against Vero, KB, MCF-7 and NCI-H187 with IC50 values of 0.0347, 6.15, 3.36 and 0.0352 µg ml-1, respectively.

Saccharothrix obliqua sp. nov., isolated from soil of Sichang Island, Thailand.

During an investigation of rare actinobacteria, isolate SC076T was isolated from a soil sample collected from Sichang Island, Chonburi Province, Thailand. The strain showed the highest 16S rRNA gene similarity to Saccharothrix australiensis DSM 43800T (98.6%) and Saccharothrix espanaensis DSM 44229T (98.6%). The zigzag morphology of the spore chain was observed on the aerial mycelia. meso-Diaminopimelic acid was detected in the peptidoglycan. Whole-cell sugars contained rhamnose, ribose, mannose glucose and galactose. Polar lipids were phosphatidylethanolamine, hydroxyphosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol, unidentified ninhydrin-positive glycolipid, unidentified glycolipid and four unidentified lipids. The menaquinones were MK-9(H8), MK-9(H4), MK-9(H2) and MK-9(H0). The predominant fatty acids were iso-C16 : 0, iso-C15 : 0 and anteiso-C17 : 0. The draft genome of SC076T was 8040245 bp with a G+C content of 72.5 mol%. The results of genomic analysis between strain SC076T and the related type strains showed that the digital DNA-DNA hybridization and average nucleotide identity values among the strains were 23.6-32.8% and 77.7-86.8 %, respectively, which are lower than the thresholds used to distinguish strains from others of the same species. Based on the taxonomic evidence, strain SC076T represents a novel species of the genus Saccharothrix for which the name Saccharothrix obliqua sp. nov. is proposed. The type strain is SC076T (=TBRC 14540T=NBRC 115117T).

Actinomadura parmotrematis sp. nov., isolated from the foliose lichen, Parmotrema praesorediosum (Nyl.) Hale.

A novel actinomycete strain PM05-2T was isolated from the lichen Parmotrema praesorediosum (Nyl.) Hale collected from Chaiyaphum Province, Thailand. The taxonomic position of the strain was studied using the polyphasic approach. Based on the morphology and chemotaxonomic properties, strain PM05-2T was identified as a member of the genus Actinomadura. The whole-cell hydrolysate contained meso-diaminopimelic acid, rhamnose, ribose, xylose, madurose, glucose and galactose. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, one unidentified phosphoglycolipid, four unidentified phospholipids and one unidentified lipid. The menaquinones were MK-9(H6), MK-9(H4), MK-9(H2), MK-9(H8) and MK-9(H0). The major cellular fatty acids were C16:0 and C18:1 ω9c. Strain PM05-2T showed the highest 16S rRNA gene similarity to Actinomadura hibisca NBRC 15177T (98.58%), Actinomadura kijaniata NBRC 14229T (98.29 %) and Actinomadura namibiensis DSM 44197T (98.14 %). The phylogenetic tree analysis revealed that strain PM05-2T was related to A. hibisca NBRC 15177T, A. kijaniata NBRC 14229T, A. namibiensis DSM 44197T and Actinomadura macrotermitis RB68T. The genomic analysis revealed that average nucleotide identity values based on both blast and MUMmer between strain PM05-2T and the relative type strains ranged from 77.6 to 86.4%. The digital DNA-DNA hybridization values among the strains were lower than the threshold for assigning to the same species. The taxonomic results suggested that strain PM05-2T represented a novel species of the genus Actinomadura for which the name Actinomadura parmotrematis is proposed. The type strain is PM05-2T (=TBRC 15492T=NBRC 115416T).

Diversity of the culturable lichen-derived actinobacteria and the taxonomy of Streptomyces parmotrematis sp. nov.

A total of 37 actinobacteria were isolated from eighteen lichen samples collected in Thailand. Based on the 16S rRNA gene sequences, they were identified into five genera including Actinoplanes (1 strain), Actinomadura (1 strain), Pseudosporangium (1 strain), Wangella (1 strain) and Streptomyces (33 strains). Among these isolates, strain Ptm05T, Ptm01 and Ptm12 showed low 16S rRNA gene similarity and was selected for the further taxonomic study using the polyphasic approach. These strains showed the highest 16S rRNA gene sequence similarity with Streptomyces sparsogenes ATCC 25498T (97.44-97.72%). Strain Ptm05T was selected for the type strain. The chemical cell composition of the strain was similar to the members of Streptomyces genus. LL-diaminopimelic acids were detected in the peptidoglycan. Menaquinones were MK-9(H8) and MK-9(H6). Phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, one unidentified phospholipid, one unidentified glycolipid and one unidentified lipid were detected as the polar lipids. The predominant cellular fatty acids are anteiso-C15:0, iso-C15:0, iso-C16:0, iso-C17:0 and C16:0. The dDNA-DNA hybridization values among strain Ptm05T and its closely related Streptomyces type strains were 17.2-18.0%. In addition, the ANIb and ANIm between strain Ptm05T and related Streptomyces type strains were ranged from 75.69 to 76.13% and 85.21 to 85.35%, respectively. Based on phenotypic and genomic evidence, strain Ptm05T (= TBRC 14546T = NBRC 115203T) represents the novel species of the genus Streptomyces for which the name Streptomyces parmotrematis sp. nov. is proposed. This study showed that the lichens are the promising source of the novel actinobacterial taxa.

Streptomyces corallincola and Kineosporia corallincola sp. nov., two new coral-derived marine actinobacteria.

Two new marine actinobacteria, designated as J2-1T and J2-2T, were isolated from a coral, Favites pentagona, collected from Rayong Province, Thailand. The taxonomic positions of the two strains were identified based on polyphasic taxonomy. Based on morphological characteristics and chemotaxonomy, strains J2-1T and J2-2T were identified as members of the genus Streptomyces and Kineosporia, respectively. Strains J2-1T and J2-2T showed the highest 16S rRNA gene sequence similarity to Streptomyces broussonetiae T44T (98.62 %) and Kineosporia babensis VN05A0415T (98.08 %), respectively. Strain J2-1T had chemotaxonomic properties resembling members of the genus Streptomyces. ll-Diaminopimelic acid, glucose and ribose were detected in the whole-cell hydrolysate. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositolmannoside, unidentified aminolipid and five unidentified phospholipids were detected as the polar lipids. The major cellular fatty acids were C16 : 0 iso, C15 : 0 anteiso, C15 : 0 iso, C16 : 0, C17 : 0 anteiso, C14 : 0 iso and C17 : 0 iso. Strain J2-2T a showed similar cell composition to members of the genus Kineosporia. Both isomers of ll- and meso-diaminopimelic acid were detected in the peptidoglycan. Arabinose, galactose, madurose and xylose were observed in the whole-cell hydrolysate. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, phosphatidylcholine, an unidentified phospholipid and an unidentified glycolipid. The major cellular fatty acids were C16 : 0, C18 : 1 ω9c, C18 : 0 10-methyl, tuberculostearic acid, C18 : 0 and C17 : 0. Both strains could be distinguished from their closely related type strains according to their phenotypic characteristics. Comparative genome analysis indicated the delineation of two novel species based on digital DNA-DNA hybridization and average nucleotide identity values, which were below 70 and 95 %, respectively. The names proposed are Streptomyces corallincola sp. nov. (J2-1T=TBRC 13503T=NBRC 115066T) and Kineosporia corallincola sp. nov. (J2-2T=TBRC 13504T=NBRC 114885T).

Potential antibiotic production of Streptomyces justiciae sp. nov., isolated from the root of Justicia subcoriacea.

Endophytic actinobacterial strain 3R004T was isolated from a root of Justicia subcoriacea collected in Thailand. In this report, the taxonomic position of this strain is described using a polyphasic approach. Based on the morphological characteristics and chemical composition of its cells, strain 3R004T was identified as a member of the genus Streptomyces. It produced a long chain of cylindrical spores on aerial mycelia. ll-Diaminopimelic acid was detected in the cell wall peptidoglycan. The menaquinones were MK-9(H4), MK-9(H6) and MK-9(H8). C16 : 0, iso-C16 : 0, anteiso-C15 : 0 and iso-C15 : 0 were detected as the major cellular fatty acids. Polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and one unidentified lipid. Strain 3R004T showed the highest 16S rRNA gene similarity of 99.45 % to Streptomyces cyaneochromogenes MK-45T. The phylogenomic results indicated that strain 3R004T was close to Streptomyces aquilus GGCR-6T and Streptomyces antibioticus DSM 40234T. The DNA-DNA hybridization and average nucleotide identity values among strain 3R004T and closely related Streptomyces species were 35.5-63.1 % and 82.7-94.3 %, respectively. The type strain produced actinomycin D antibiotic as the major secondary metabolite. The maximum productivity of the actinomycin D (378 mg l-1) was observed when the strain was grown in 301 broth at 30 °C, 180 r.p.m. for 12 days. On the basis of phenotypic and genotypic evidence, strain 3R004T represents a novel species of the genus Streptomyces, for which the name Streptomyces justiciae is proposed. The type strain is 3R004T (=LMG 32138T=TBRC 13128T=NBRC 115065T).

Potential antimicrobial properties of streptomyces isolated from Sammuk Mountain soil, Chonburi Province, Thailand.

An infection of pathogenic microorganisms can create a big problem for human health. This has triggered the need for discovery and development of antibiotic drugs with altered modes of action. Approximately 45% of antibiotic drugs are derived from Streptomyces, which are the most commonly isolated actinomycete genera. The present investigation aimed to search for and study antimicrobial-producing actinomycetes isolated from soil samples from Sammuk Mountain, Chonburi province, Thailand. A total of 50 isolates from six soil samples were obtained and their actinomycetes were better isolated using humic acid-vitamin agar medium (64.0%) than starch casein nitrate agar medium (36.0%). In addition, the secondary metabolites produced from 13 isolates (26.0%) exhibited a broad spectrum of antimicrobial activity against Gram-positive bacteria and yeast. Thus, Sammuk Mountain soil is an important source of antibiotic-producing actinomycetes.

Antimicrobial substances from the rare actinomycete Nonomuraea rhodomycinica NR4-ASC07T.

Nonomuraea rhodomycinica NR4-ASC07T is a rare actinomycete isolated from soil in Sirindhorn peat swamp forest. The crude extract of its culture broth exhibited antimicrobial and anticancer against diverse human pathogens and cancer cells. The chemical investigation of the crude extract led to the isolation of two new metabolites named nonomuric acid (1) and 3-hydroxy deoxydaunorubicinol aglycone (2), along with two known bioactive compounds [ε-rhodomycinone (3) and 7-deoxy-13-dihydrocarminomycinone (4)]. Compounds 1 and 3 showed antimalarial activity with the half maximal inhibitory concentration (IC50) of 8.00 and 8.88 µg mL-1, respectively. Compound 4 inhibited growth of Mycobacterium tuberculosis and Bacillus cereus at the minimum inhibitory concentrations of 50.0 and 12.50 µg mL-1, respectively. Every compound exhibited cytotoxicity against cancer cells tested at IC50 ≥ 6.34 µg mL-1. These finding are the first report of bioactive metabolites produced by strain NR4-ASC07T, suggesting that rare actinomycetes are yet promising sources for novel drug discovery.

Nonomuraea rhodomycinica sp. nov., isolated from peat swamp forest soil.

The taxonomic position of an actinomycete, strain NR4-ASC07T, isolated from a soil sample collected from Sirindhorn peat swamp forest, Narathiwat Province, Thailand, was clarified using a polyphasic approach. On the basis of morphological and chemotaxonomic characteristics, it was classified among the members of the genus Nonomuraea. It produced tightly closed spiral spore chains on aerial mycelium as well as forming a pseudosporangium. Whole-cell hydrolysates contained meso-diaminopimelic acid, glucose, ribose, madurose and mannose. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, lyso-phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides, unknown ninhydrin-positive phosphoglycolipids and unknown glycolipid. Menaquiones were MK-9(H4), MK-9(H0), MK-9(H2), MK-10(H4) and MK-9(H6). Predominant cellular fatty acids were iso-C16 : 0, C17 : 0 10-methyl, C16 : 0, C17 : 1ω8c, C16 : 0 2-OH and iso-C15 : 0. The phylogenetic tree reconstructed on the basis of 16S rRNA gene sequences showed that the strain fell within the clade containing Nonomuraea muscovyensis FMN03T, Nonomuraea roseoviolacea subsp. roseoviolaceaNBRC 14098T and Nonomuraea roseoviolacea subsp. carminataNBRC 15903T. The DNA-DNA relatedness and phenotypic data supported that strain NR4-ASC07T was clearly distinguished from the closely related species and represents a novel species of the genus Nonomuraea for which the name Nonomuraea rhodomycinica sp. nov. is proposed. The type strain is NR4-ASC07T (=NBRC 112327T=TISTR 2465T).

Investigation on antimicrobial agents of the terrestrial Streptomyces sp. BCC71188.

The terrestrial actinomycete strain BCC71188 was identified as Streptomyces by its morphology (having spiral chain spore on the aerial mycelium), chemotaxonomy (containing LL-diaminopimelic acid in the cell wall), and 16S rRNA gene sequence analysis [showing high similarity values compared with Streptomyces samsunensis M1463T (99.85 %) and Streptomyces malaysiensis NBRC 16446T (99.40 %)]. The crude extract exhibited antimalarial against Plasmodium falciparum (IC50 0.19 µg/ml), anti-TB against Mycobacterial tuberculosis (MIC 6.25 µg/ml), and antibacterial against Bacillus cereus (MIC 1.56 µg/ml) activities. Therefore, chemical investigation was conducted by employing bioassay-guided method and led to the isolation of 19 compounds including two cyclic peptides (1-2), five macrolides (3-7), new naphthoquinone (8), nahuoic acid C (9), geldanamycin derivatives (10-13), cyclooctatin (14), germicidins A (15) and C (16), actinoramide A (17), abierixin, and 29-O-methylabierixin. These isolated compounds were evaluated for antimicrobial activity, such as antimalarial, anti-TB, and antibacterial activities, and for cytotoxicity against both cancerous (MCF-7, KB, NCI-H187) and non-cancerous (Vero) cells. Compounds 1-7, 10-14 exhibited antimalarial (IC50 0.22-7.14 µg/ml), and elaiophylin analogs (4-6) displayed anti-TB (MIC 0.78-12.00 µg/ml) and B. cereus (MIC 0.78-3.13 µg/ml) activities. Compounds 1, 2, 14, and abierixin displayed weak cytotoxicity, indicating a potential for antimicrobial agents.

Streptomyces krungchingensis sp. nov., isolated from soil.

A novel actinomycete, designated strain KC-035T, was isolated from soil collected from Krung Ching Waterfall National Park, Nakhon Si Thammarat Province, Thailand. Its taxonomic position was determined using a polyphasic approach. The strain had morphological and chemotaxonomic properties typical of members of the genus Streptomyces: flexuous spore chain; ll-diaminopimelic acid in the cell-wall peptidoglycan; MK-9(H8), MK-9(H6) and MK-9(H4) as menaquinones; diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside as phospholipids; anteiso-C15 : 0, C16 : 0, iso-C16 : 0, iso-C15 : 0 and iso-C14 : 0 as major cellular fatty acids; and DNA G+C content of 72 mol%. 16S rRNA gene sequence analysis revealed that strain KC-035T showed high similarity to Streptomyces albiflavescens n20T (99.16 %) and Streptomyces siamensis KC-038T (98.43 %) as well as formed a monophyletic clade with them in the phylogenetic tree. On the basis of comparison of phenotypic properties and the low level of DNA-DNA relatedness, strain KC-035T could be distinguished from its closely related Streptomyces species and is considered to represent a novel species of the genus Streptomyces, for which the name Streptomyces krungchingensis sp. nov. is proposed. The type strain is KC-035T (=NBRC 110087T=KCTC 29503T=TISTR 2402T).

Streptomyces andamanensis sp. nov., isolated from soil.

A novel actinomycete, strain KC-112T, was isolated from soil collected from Similan Islands, Phang-Nga Province, Thailand. The strain exhibited morphological and chemotaxonomic characteristics consistent with those of members of the genus Streptomyces. The formation of smooth spiral spore chains was observed on aerial mycelia. ll-Diaminopimelic acid was detected in whole-cell hydrolysates, but no diagnostic sugars were detected and the strain lacked mycolic acids. The N-acyl type of muramic acid was acetyl. The major menaquinones were MK-9(H8), MK-9(H6) and MK-9(H2). The predominant cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0, iso-C16 : 0 and C16 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, an unknown phospholipid, an unknown aminolipid, unknown lipids and an unknown glycolipid. The DNA G+C content was 73 mol%. On the basis of 16S rRNA gene sequence analysis, strain KC-112T was closely related to Streptomyces fumanus NBRC 13042T (98.8 % 16S rRNA gene sequence similarity), Streptomyces anandii NBRC 13438T (98.8 %) and Streptomyces capillispiralis NBRC 14222T (98.8 %). DNA-DNA relatedness values among strain KC-112T and type strains of closely related species were lower than 70 %. On the basis of evidence from this taxonomic study using a polyphasic approach, strain KC-112T represents a novel species of the genus Streptomyces, namely Streptomyces andamanensis sp. nov. The type strain is KC-112T ( = KCTC 29502T = NBRC 110085T = PCU 347T = TISTR 2401T).

Streptomyces siamensis sp. nov., and Streptomyces similanensis sp. nov., isolated from Thai soils.

Three actinomycete strains, KC-038(T), KC-031 and KC-106(T), were isolated from soil samples collected in the southern Thailand. The morphological and chemotaxonomic properties of strains KC-038(T), KC-031 and KC-106(T) were consistent with the characteristics of members of the genus Streptomyces, that is, the formation of aerial mycelia bearing spiral spore chains; the presence of LL-diaminopimelic acid in the cell wall, MK-9 (H6), MK-9 (H4) and MK-9 (H8) as the predominant menaquinones; and C16:0, iso-C16:0 and anteiso-C15:0 as the major cellular fatty acids. 16S rRNA gene sequence analyses indicated that strains KC-038(T) and KC-031 were highly similar (99.9%), and they were closely related to S. olivochromogenes NBRC 3178(T) (98.1%) and S. psammoticus NBRC 13971(T) (98.1%). Strain KC-106(T) was closely related to S. seoulensis NBRC 16668(T) (98.9%), S. recifensis NBRC 12813(T) (98.9%), S. chartreusis NBRC 12753(T) (98.7%) and S. griseoluteus NBRC 13375(T) (98.4%). The values of DNA-DNA relatedness between the isolates and the type strains of the related species were below 70%. On the basis of the polyphasic evidence, the isolates should be classified as two novel species, namely Streptomyces siamensis sp. nov. (type strain, KC-038(T) = NBRC 108799(T) = PCU 328(T) = TISTR 2107(T)) and Streptomyces similanensis sp. nov. (type strain, KC-106(T) = NBRC 108798(T) = PCU 329(T) = TISTR 2104(T)).

Nonomuraea thailandensis sp. nov. isolated from Thai soil.

A novel actinomycete, strain KC-061(T) was isolated from a soil sample collected from Angthong Islands National Park, Surat Thani province, Thailand. Strain KC-061(T) was identified as a member of the genus Nonomuraea through the use of a polyphasic approach. Phylogenetic analyses based on 16S rRNA gene sequencing, strain KC-061(T) belongs to the genus Nonomuraea and was closely related to 'N. monospora' PT708(T) (99.3%), N. rhizophila YIM 67092(T) (98.6%), N. dietziae DSM 44320(T) (98.5%) and N. rosea GW 12687(T) (98.3%). On the basis of phenotypic characteristics, DNA-DNA relatedness and phylogenetic distinctiveness, the novel isolate was identified as representing a novel species of the genus Nonomuraea, for which the name Nonomuraea thailandensis sp. nov. (type strain KC-061(T) =JCM 18408(T)=KCTC 29074(T) =PCU 327(T)) is proposed.