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Pradimicin U is a new dihydrobenzo[a]naphthacenequinone compound found to be active on a screen designed to investigate compounds with antimicrobial activity, produced by the actinomycete designated strain FMUSA5-5 T . The strain was isolated from a bio-fertilizer of Musa spp. collected from Suphanburi province, Thailand. The chemotaxonomic characteristics and 16S rRNA gene analysis revealed that strain FMUSA5-5 T is a member of the genus Nonomuraea. Low genome-based taxonomic criteria, average nucleotide identity (ANI) (82.8-88.3%), average amino-acid identity (AAI) (79.4-87.3%), and digital DNA-DNA hybridization (dDDH) (29.5-38.5%) values and several phenotypic differences between strain FMUSA5-5 T and its closest type strains of the genus Nonomuraea indicated that strain FMUSA5-5 T represents a novel species of the genus Nonomuraea and the name Nonomuraea composti sp. nov. is proposed for the strain. The crude extract from the culture broth of strain FMUSA5-5 T displayed promising antimicrobial activity against several pathogens and led to the isolation of a novel secondary metabolite, pradimicin U. Interestingly, this compound displayed a broad spectrum of biological activities such as antimalarial activity against Plasmodium falciparum K1 (IC 50 value = 3.65 µg/mL), anti-Mycobacterium tuberculosis H37Ra (MIC value = 25.0 µg/mL), anti-Alternaria brassicicola BCC 42724 (MIC value = 25.0 µg/mL), anti-Bacillus cereus ATCC 11778 and anti-Staphylococcus aureus ATCC 29213 (MIC values = 6.25 and 1.56 µg/mL, respectively). Moreover, the compound possessed strong anti-human small cell lung cancer (NCI-H187) activity with IC 50 value of 5.69 µg/mL, while cytotoxicity against human breast cancer (MCF-7) and Vero cells was very weak (IC 50 values of 52.49 and 21.84 µg/mL, respectively)., (© 2024. The Author(s).)

An endophytic actinobacterium, designated strain PLAI 1-29 T , was isolated from the root tissue of Zingiber montanum collected from Pathum Thani province, Thailand. Strain PLAI 1-29 T was characterized using a polyphasic taxonomic approach. It typically exhibited morphological and chemotaxonomic properties of the genus Streptomyces . Strain PLAI 1-29 T produced a spiral spore chain on aerial mycelium and grew at 15-40 °C, pH 6-10 on International Streptomyces Project 2 agar. The maximum NaCl concentration for growth was 9 % (w/v). Cells of strain PLAI 1-29 T presented ll -diaminopimelic acid, arabinose, galactose and ribose. The detected phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside. The major menaquinones were MK-9(H 6 ) and MK-9(H 8 ). The major cellular fatty acids were iso -C 16 : 0 , anteiso -C 15 : 0 and anteiso -C 17 : 0 . The genome-based taxonomic details revealed the assignment of strain PLAI 1-29 T to the genus Streptomyces and exhibited low threshold values for the delineation of a novel species by average nucleotide identity-blast (84.0%), average amino acid identity (80.0%) and digital DNA-DNA hybridization (27.6%) with its closest type strain, Streptomyces xinghaiensis S187 T . Furthermore, several differential physiological and biochemical characteristics were detected between strain PLAI 1-29 T and the closest type strain. Based on the combined phenotypic and genomic features, strain PLAI 1-29 T (=TBRC 7645 T =NBRC 113170 T ) is considered to represent a new Streptomyces species, for which we propose the name Streptomyces zingiberis sp. nov.

An actinobacterium strain, PPF5-17 T , was isolated from hot spring soil collected from Chiang Rai province, Thailand. The strain exhibited morphological and chemotaxonomic properties similar to those of members of the genus Micromonospora . Colonies of PPF5-17 T were strong pinkish red and turned black after sporulation in ISP 2 agar medium. Cells formed single spores directly on the substrate mycelium. Growth was observed from 15 to 45 °C and at pH 5-8. Maximum NaCl concentration for growth was 3 % (w/v). PPF5-17 T was found to have meso -diaminopimelic acid, xylose, mannose and glucose in the whole-cell hydrolysate. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositolmannosides were observed as the membrane phospholipids. MK-10(H 6 ), MK-9(H 6 ), MK-10(H 4 ) and MK-9(H 4 ) were the major menaquinones. The predominant cellular fatty acids were iso-C 15 : 0 , iso-C 17 : 0 , anteiso-C 17 : 0 and iso-C 16 : 0 . PPF5-17 T shared the highest 16S rRNA gene sequence similarity with Micromonospora fluminis LMG 30467 T (99.3 %). A genome-based taxonomic study revealed that PPF5-17 T was closely related to Micromonospora aurantinigra DSM 44815 T in the phylogenomic tree with an average nucleotide identity by blast (ANIb) of 87.7 % and a digital DNA-DNA hybridization (dDDH) value of, 36.1 % which were below the threshold values for delineation of a novel species. Moreover, PPF5-17 T could be distinguished from its closest neighbours, M. fluminis LMG 30467 T and M. aurantinigra DSM 44815 T , with respect to a broad range of phenotypic properties. Thus, PPF5-17 T represents a novel species, for which the name Micromonospora solifontis sp. nov. is proposed. The type strain is PPF5-17 T (= TBRC 8478 T = NBRC 113441 T ).

An actinobacterium, designated strain SS06011 T , was isolated from solar saltern soil collected from Samut Sakhon province, Thailand. The taxonomic position of this strain was established using the polyphasic taxonomic approach. The strain produced grey aerial spore mass on International Streptomyces Project 2 seawater agar that differentiated into spiral spore chains with rugose-surfaced spores. Strain SS06011 T was found to have ll -diaminopimelic acid in the cell peptidoglycan. Whole-cell hydrolysates contained galactose, glucose and ribose. MK-9(H 6 ) and MK-9(H 4 ) were major menaquinones. The major cellular fatty acids comprised iso -C 16 : 0 , anteiso -C 15 : 0 and anteiso -C 17 : 0 . Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol were detected in cells. These characteristics were coincident with the typical morphological and chemotaxonomic properties of the genus Streptomyces . The taxonomic affiliation at the genus level of this strain could also be confirmed by its 16S rRNA gene sequence data. Strain SS06011 T showed the highest 16S rRNA gene sequence similarity to Streptomyces ardesiacus NRRL B-1773 T (99.1 %), Streptomyces coelicoflavus NBRC 15399 T (99.1 %) and Streptomyces hyderabadensis OU-40 T (99.1 %). Digital DNA-DNA hybridization (dDDH), average nucleotide identity-blast (ANIb) and average amino acid identity (AAI) values between strain SS06011 T and its closely related type strains, S. ardesiacus NBRC 15402 T , S. coelicoflavus NBRC 15399 T and S. hyderabadensis JCM 17657 T , were in the range of 45.4-48.4 % (for dDDH), 90.8-91.9 % (for ANIb) and 90.8-91.7 % (for AAI), respectively, which are lower than the cut-off criteria for species delineation. The DNA G+C content of genomic DNA was 71.9 mol%. With the differences in physiological, biochemical and genotypic data, strain SS06011 T could be discriminated from its closest neighbours. Thus, strain SS06011 T should be recognized as representing a novel species of the genus Streptomyces , for which the name Streptomyces salinarius sp. nov. is proposed. The type strain is SS06011 T (=TBRC 9951 T =NBRC 113998 T ).

An actinomycete, designated strain HSS6-12 T , was isolated from hot spring sediment collected from Ranong province, Thailand. The strain showed taxonomic characteristics consistent with those of members of the genus Micromonospora. HSS6-12 T produced a single spore directly on the substrate mycelium, and no aerial mycelium was detected. The isomer of diamino acid presented in cell wall peptidoglycan was meso-diaminopimelic acid. Arabinose, xylose, glucose, and ribose were detected in whole-cell hydrolysates. MK-10(H 4 ), MK-9(H 4 ), and MK-10(H 6 ) were major menaquinones. Major cellular fatty acids were iso-C 16:0 , iso-C 15:0 , and iso-C 17:0 . Phospholipid profile was composed of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, and phosphatidylinositolmannosides. 16S rRNA gene analysis revealed that HSS6-12 T shared the highest 16S rRNA gene sequence similarity with Micromonospora inositola DSM 43819 T (99.3%). In contrast, the genome analysis showed that HSS6-12 T formed a tight taxonomic position in a phylogenomic tree with Micromonospora endolithica DSM 44398 T . Moreover, the average nucleotide identity-blast, the digital DNA-DNA hybridization, and the average amino acid identity values between HSS6-12 T and M. inositola DSM 43819 T and M. endolithica DSM 44398 T were 83.1-84.0%, 27.5-28.7%, and 80.4-82.2%, respectively, indicating that HSS6-12 T was different species with both closely related Micromonospora-type strains. In addition, HSS6-12 T could be discriminated from its closely related type strains by many physiological and biochemical characteristics. Thus, HSS6-12 T could be considered a novel species of the genus Micromonospora, and the name Micromonospora thermarum is proposed for the strain. The type strain is HSS6-12 T (= BCC 41915 T  = JCM 17127 T )., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

An actinobacterium strain, SW21 T , was isolated from seawater collected in the upper Gulf of Thailand. Cells were Gram-stain-positive, aerobic and rod-shaped. Growth was observed from 15 to 37 °C and at pH 6-8. Maximum NaCl for growth was 14 % (w/v). meso -Diaminopimelic acid, arabinose, galactose, glucose, rhamnose and ribose were detected in the whole-cell hydrolysate. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside were detected as the phospholipids in the cells. The major menaquinones were MK-9(H 2 ) and MK-7(H 2 ). The major cellular fatty acids were C 16 : 0 , C 18 : 1  ω 9 c , C 18 : 0 and C 18 : 0 10-methyl (TBSA). The 16S rRNA gene sequence data supported the assignment of strain SW21 T to the genus Gordonia and showed that Gordonia mangrovi KCTC 49383 T (98.7 %) was the closest relative. Moreover, the average nucleotide identity-blast (85.5 %) and digital DNA-DNA hybridization (30.7 %) values between strain SW21 T and its closest neighbour were below the threshold values for delineation of a novel species. The combination of genotypic and phenotypic data indicated that strain SW21 T is representative of novel species of the genus Gordonia . The name Gordonia aquimaris sp. nov. is proposed for strain SW21 T . The type strain is SW21 T (=TBRC 15691 T =NBRC 115558 T ).

Seven undescribed compounds, including four naphthoquinone terpenoids (aculeolatins A - D), one rare 2-nitropyrrole terpenoid (nitropyrrolin F), and two hydroxamate siderophores (aculeolamides A and B) and one further undescribed compound (2,5,7-trihydroxy-3,6-dimethylnaphthalene-1,4-dione), together with eleven known compounds (arromycin, phenaziterpene A, nitropyrrolin A, heronapyrroles A and B, salaceyin A, 5,7-dihydroxy-2-isopropylchromone, 1-hydroxyphenazine, 1-methoxyphenazine, 1-acetyl-β-carboline, and N-(2-phenylethyl) acetamide), were isolated from the cultures of the endophytic Streptomyces aculeolatus MS1-6. The structures of the isolated compounds were determined using NMR spectroscopy and corroborated using chemical modification. These compounds exhibited a broad spectrum of biological activities, including antimalarial (IC 50 6.03-9.84 μg/mL), antitubercular (MIC 3.13-6.25 μg/mL), anti-plant pathogenic fungal (MIC 25.0-50.0 μg/mL), and antibacterial (MIC 3.03-50 μg/mL) activities; however, they displayed unremarkable cytotoxicity against cancerous (MCF-7 and NCI-H187) and non-cancerous (Vero) cell lines., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A member of the genus Streptomyces , designated RCPT1-4 T , was isolated from compost of Senna siamea (Lam.), collected from an agricultural area in Rayong province, Thailand. The spore morphology and the presence of ll-diaminopimelic acid in the peptidoglycan indicate that RCPT1-4 T shows the typical properties of members of the genus Streptomyces . On the basis of the results of 16S rRNA gene sequence analysis, the strain should be classified as representing a member of the genus Streptomyces and was most closely related to Streptomyces fumigatiscleroticus NBRC 12999 T with the highest 16S rRNA gene sequence similarity of 99.2 %, followed by Streptomyces spiralis NBRC 14215 T (99.0 %). In addition, RCPT1-4 T shared the highest average nucleotide identity by blast (ANIb) (86.0 %), and digital DNA-DNA hybridization (dDDH) (32.1 %) values with S. spiralis NBRC 14215 T . Furthermore, several physiological and biochemical differences were observed between RCPT1-4 T and the closely related type strains of species with validly published names. These taxonomic data indicated that RCPT1-4 T could be considered to represent a novel species of the genus Streptomyces and the name Streptomyces sennicomposti sp. nov. is proposed for this strain. The type strain is RCPT1-4 T (=TBRC 11260 T =NBRC 114303 T ).

An aerobic, non-motile, Gram-stain positive actinomycete, designated strain CA3R110 T , was isolated from the surface-sterilised root of Coffea arabica L. collected from Lampang Province, Thailand. 16S rRNA gene sequence analysis indicated that strain CA3R110 T was a member of the genus Streptomyces and showed the closest similarities to Streptomyces buecherae AC541 T (99.2%), followed by Streptomyces rapamycinicus NRRL B-5491 T (99.1%), Streptomyces luteoverticillatus NBRC 3840 T (99.1%), Streptomyces coerulescens NBRC 12758 T (99.1%), and Streptomyces iranensis HM 35 T (99.0%). Strain CA3R110 T contained LL-diaminopimelic acid in cell peptidoglycan, MK-9(H 6 ), and MK-9(H 8 ) as major menaquinone, iso-C 16:0, iso-C 15:0, C 16:0 as major fatty acids. Diphosphatidylglycerol, phosphatidylethanolamine, hydroxy-phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositolmannoside were detected in the cell. The chemotaxonomic characteristics possessed the typical properties of the genus Streptomyces. A low digital DNA-DNA hybridization (< 55.7%) and average nucleotide identity-blast (ANIb) (< 92.2%) values revealed that strain CA3R110 T could be distinguished from any known Streptomyces species. With the differences in phenotypic and genotypic data, strain CA3R110 T represents a novel species of genus Streptomyces, for which the name Streptomyces endocoffeicus sp. nov. is proposed. The type strain is CA3R110 T (= TBRC 11245 T  = NBRC 114296 T )., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Nine new chromone analogs ( 1 - 9 ) were isolated from the soil actinomycete Microbispora sp. TBRC6027. The chemical structures were determined based upon NMR spectroscopic methods. These compounds were evaluated in vitro by using P19-derived neurons for neuroprotective activity against oxidative stress induced by serum deprivation and showed % viability of neurons at the concentration of 1 ng/mL varied from 43.51% to 52.99% without significant neurotoxicity for P19-derived neurons at the same concentration. Moreover, all tested compounds were inactive for antibacterial activity against both Gram-positive and Gram-negative bacteria and for cytotoxicity against MCF-7 (human breast cancer) and Vero cells at maximum tested concentration 50 μg/mL. However, compounds 4 , 6 , and 7 displayed weak cytotoxicity against NCI-H187 (human small-cell lung cancer) cells with IC 50 in a range of 87.99-91.57 μM.

Three undescribed abyssomicin derivatives, including microbimisin, abyssomicins Z1, and Z2, were isolated from the soil actinomycete Microbispora rhizosphaerae sp. nov. TBRC6028. Chemical structures were determined by NMR spectroscopic data ( 1 H, 13 C, COSY, HSQC, HMBC, and NOESY spectra) and the absolute configurations were verified by single-crystal X-ray diffraction analyses together with the ECD spectral data. Microbimisin and abyssomicin Z1 exhibited weak antibacterial activity against Bacillus cereus with MIC values of 25.0 and 50.0 μg/mL without cytotoxicity against MCF-7 and Vero cells at the concentration of 50 μg/mL., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

An actinomycete strain CSR-4 was isolated from the rhizosphere soil of Zingiber montanum. Taxonomic characterization revealed strain CSR-4 was a member of the genus Microbispora. Whole-genome sequence analysis exhibited the highest average nucleotide identity (ANI) value (95.34%) and digital DNA-DNA hybridization (DDH) value (74.7%) between strain CSR-4 and the closest relative M. hainanensis DSM 45428 T , which was in line with the assignment to same species. In addition, a new diterpene compound, 2α-hydroxy-8(14), 15-pimaradien-17, 18-dioic acid, and nine known compounds were isolated from the ethyl acetate crude extract of fermentation broth. Interestingly, a new diterpene displayed the suppressive effect on the recombinant human acetylcholinesterase (rhAChE) enzymes (IC 50 96.87 ± 2.31 μg/ml). In silico studies based on molecular docking and molecular dynamics (MD) simulations were performed to predict a binding mode of the new compound into the binding pocket of the rhAChE enzyme and revealed that some amino acids in the peripheral anions site (PAS), anionic subsite, oxyanion site and catalytic active site (CAS) of the rhAChE have interacted with the compound. Therefore, our new compound could be proposed as a potential active human AChE inhibitor. Moreover, the new compound can protect significantly the neuron cells (% neuron viability = 88.56 ± 5.19%) from oxidative stress induced by serum deprivation method at 1 ng/ml without both neurotoxicities on murine P19-derived neuron cells and cytotoxicity against Vero cells.

An endophytic actinobacterium, designated strain KE2-3 T , was isolated from surface-sterilised rhizome of Kaempferia elegans. The polyphasic approach was used for evaluating the taxonomic position of this strain. The taxonomic affiliation of this strain at genus level could be confirmed by its chemotaxonomic characteristic, i.e. the presence of ll-diaminopimelic acid in the cell peptidoglycan, MK-9(H4) as the major menaquinone, iso-C16 : 0, anteiso-C15 : 0, iso-C14 : 0 and iso-C15 : 0 as the predominant fatty acids in cells, and the presence of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside in its membranes. Based on 16S rRNA gene sequence analysis, strain KE2-3 T was identified as a member of the genus Jiangella and showed the highest similarities to Jiangella muralis DSM 45357 T (99.3 %) followed by Jiangella albaDSM 45237 T (99.2 %), Jiangella alkaliphilia DSM 45079 T (99.0 %), Jiangella gansuensisDSM 44835 T (98.8 %) and Jiangella mangrovi3SM4-07 T (98.6 %). However, the draft genome sequence of strain KE2-3 T exhibited low average nucleotide identity values to the reference strains (85.5-90.2 %), which were well below the 95-96 % species circumscription threshold. The DNA G+C content of genomic DNA was 72.3 mol%. With the differences of physiological, biochemical and genotypic data, strain KE2-3 T could be discriminated from its closest neighbour. Thus, strain KE2-3 T should be recognised as a novel species of genus Jiangella, for which the name Jiangellaendophytica sp. nov. is proposed. The type strain is KE2-3 T (=BCC 66359 T =NBRC 110004 T ).

A novel actinomycete strain PS42-9 T , which formed short chains of spores borne on the tip of long sporophores arising from the substrate mycelium, was isolated from soil in Phu-Sang National Park, Phayao province, Thailand. The isolate contained meso-diaminopimelic acid in the cell-wall peptidoglycan. The whole-cell sugars of strain PS42-9 T were glucose, madurose, mannose, rhamnose and ribose. The characteristic phospholipids were phosphatidylethanolamine, phosphatidylmethylethanolamine, hydroxyphosphatidylethanolamine and ninhydrin-positive glycophospholipids. The major menaquinone was MK-10(H4). The main cellular fatty acids were C17 : 1ω8c and C17 : 0. The G+C content of the genomic DNA was 71.5 mol%. Phylogenetic analysis using 16S rRNA gene sequences revealed that strain PS42-9 T should be classified in the genus Herbidospora and was closely related to Herbidospora sakaeratensis DMKUA 205 T (99.10 %) and Herbidospora yilanensis NBRC 106371 T (98.61 %). The result of DNA-DNA hybridization and some physiological and biochemical properties indicated that strain PS42-9 T could be readily distinguished from its closest phylogenetic relatives. On the basis of these phenotypic and genotypic data, this strain represents a novel species, for which the name Herbidospora soli sp. nov. is proposed. The type strain is PS42-9 T (=BCC 46909 T =NBRC 108780 T ).