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    Streptomyces odontotermitis Odt1-20BT, an actinobacterium isolated from the fungus-growing Odontotermes formosanus
    (2026-08-01)
    Supong, Khomsan
    ;
    Niemhom, Nantawan
    ;
    Suriyachadkun, Chanwit
    ;
    Tanasupawat, Somboon
    ;
    Pittayakhajonwut, Pattama
    A novel culturable insect-derived actinobacterium, designated strain Odt1-20B<sup>T</sup>, was isolated from Odontotermes formosanus. The cells exhibited aerobic, Gram-stain-positive, and filamentous characteristics. Strain Odt1-20B<sup>T</sup> formed well-developed substrate and aerial mycelia, with straight spore chains borne on the aerial mycelium. Strain Odt1-20B<sup>T</sup> grew at 20–40 °C (optimum 30 °C), 0˗4% (w/v) NaCl, and pH 5˗10 (optimum 7−8). The l,l-diaminopimelic acid was determined in the whole-cell hydrolysate of strain Odt1-20B<sup>T</sup>. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine, whereas the detected major quinones were MK-9(H<inf>4</inf>), MK-9(H<inf>6</inf>), and MK-9(H<inf>8</inf>). Whole-cell sugars were galactose, glucose, mannose, ribose, and xylose. Summed feature C<inf>18:1</inf> ω6c/ω7c, C<inf>16:0</inf>, anteiso-C<inf>15:0</inf>, and iso-C<inf>16:0</inf> were the main fatty acids. The draft genome size was 10,091,787 nucleotides, with a G + C content of 71.5%. Comparative phylogenetic analysis based on 16S rRNA gene sequence demonstrated that strain Odt1-20B<sup>T</sup> belonged to the genus Streptomyces, and shared the highest similarity with S. davaonensis JCM 4913 <sup>T</sup> (98.55%). Furthermore, phylogenomic analysis showed that strain Odt1-20B<sup>T</sup> was clearly distinguished from the closely related Streptomyces species. The average nucleotide identity analyses based on BLAST (ANIb) and MUMmer (ANIm) between strain Odt1-20B<sup>T</sup> and its related species ranged below 87%, and the digital DNA-DNA hybridization (dDDH) values ranged from 21.2% to 29.9%, all of which are below the species delimitation thresholds. The results of polyphasic taxonomy clearly indicated that strain Odt1-20B<sup>T</sup> represents a novel species, proposed as Streptomyces odontotermitis sp. nov. with the type strain Odt1-20B<sup>T</sup> (= NBRC 116112 <sup>T</sup> = TBRC 16156 <sup>T</sup>).
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    Characterization, comparative genomics, and metabolome analysis of Streptomyces tuberiscabiei sp. nov., a novel actinomycete causing potato scab disease in Long Khot, Chiang Mai Province, Thailand
    (2026-07-01)
    Inthong, Tanchanok
    ;
    Wannawong, Thippawan
    ;
    Mhuantong, Wuttichai
    ;
    Hongprasit, Aphinan
    ;
    Tanasupawat, Somboon
    Three actinomycete strains, WSLK1–3<sup>T</sup>, WSLK1–4, and WSLK1–5, associated with scabby potato tuber, were characterized using polyphasic and genome-based taxonomy. All strains were found to be Gram-stain-positive, filamentous bacteria, including LL-diaminopimelic acid in cell-wall peptidoglycan. Whole-cell sugars were glucose, mannose, rhamnose, and ribose. MK-9(H<inf>6</inf>) and MK-9(H<inf>10</inf>) were major menaquinones; C<inf>16:0</inf>, isoC<inf>16:0</inf>, ante iso-C<inf>15:0</inf>, and anteiso -C<inf>17:0</inf> were major cellular fatty acids; diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, and phosphatidylinositol mannoside were major phospholipids; and DNA G + C contents were 71.5 mol%. Phylogenetic analysis based on 16S rRNA gene and genome sequences indicated that strains WSLK1–3<sup>T</sup>, WSLK1–4, and WSLK1–5 are closely related to Streptomyces canus DSM 40017<sup>T</sup> (=JCM 4212<sup>T</sup>), and S. pseudovenezuelae DSM 40212<sup>T</sup> (=JCM 11516<sup>T</sup>), respectively. The 16S rRNA gene sequences, average nucleotide identity based on BLAST (ANIb) and MUMmer (ANIm), and digital DNA-DNA hybridization (dDDH) values among the three strains were 100%, 99.12%, 99.33%, and 94.3%, respectively, indicating that these strains belong to the same species. Strains WSLK1–3<sup>T</sup>, WSLK1–4, and WSLK1–5 showed 88.54–90.62% ANIb, 90.99–92.27% ANIm, and 40.4–45.1% to their closely related type strains: S. canus JCM 4212<sup>T</sup>, and S. pseudovenezuelae JCM 11516<sup>T</sup>. All novel strains were pathogenic, causing necrosis on potato tuber slices, inhibiting plant seedlings, and inducing superficial to raised scab lesions on potato tubers. Based on the phenotypic, chemotaxonomic, pathogenic, and genomic data, strains WSLK1–3<sup>T</sup>, WSLK1–4, and WSLK1–5 could be assigned to the novel species within the genus Streptomyces for which the name Streptomyces tuberiscabiei sp. nov. is proposed. The type strain is WSLK1–3<sup>T</sup> (=TBRC 19150<sup>T</sup> = LMG 33893<sup>T</sup>).
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    Advanced chitosan hybrid dye labels for dynamic monitoring of shrimp and milk freshness
    (2025-04-01)
    Ronte, Arnat
    ;
    Chalitangkoon, Jongjit
    ;
    Sintoppun, Tanaporn
    ;
    Niemhom, Nantawan
    ;
    Manapradit, Nuttaporn
    This study presents the development of intelligent screen-printed labels for real-time food freshness monitoring. Using chitosan grafted with rosolic acid (RA) and immobilized on montmorillonite (MMT) through cationic exchange, a hybrid dye was synthesized and applied in screen-printing inks. The hybrid structure was characterized by XRD, TGA, and UV–vis, confirming improved thermal stability and maintained halochromic properties. SEM analysis showed consistent ink deposition on filter paper, while water contact angle (WCA) measurements demonstrated enhanced surface hydrophobicity due to the MMT. The labels exhibited clear pH-sensitive color transitions from yellow to purplish red (pH 2.0–12.0) and rapid ammonia sensitivity, with ΔE values exceeding 45.0 within 10 min. The labels also demonstrated excellent reversibility, storage stability, leaching resistance, and cytocompatibility. Practical tests on shrimp and milk confirmed the labels' ability to accurately monitor freshness through visible color changes. These findings highlight the potential of hybrid labels as effective, scalable freshness indicators for intelligent food packaging.
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    Actinomycetospora termitidis sp. nov., an insect-derived actinomycete isolated from termite (Odontotermes formosanus)
    (2024-05-01)
    Supong, Khomsan
    ;
    Niemhom, Nantawan
    ;
    Suriyachadkun, Chanwit
    ;
    Phongsopitanun, Wongsakorn
    ;
    Tanasupawat, Somboon
    Strain Odt1-22<sup>T</sup>, an insect-derived actinomycete was isolated from a termite (Odontotermes formosanus) that was collected from Chanthaburi province, Thailand. Strain Odt1-22<sup>T</sup> was aerobic, Gram-stain-positive, and produced bud-like spore chain on the substrate hypha. According to chemotaxonomic analysis, strain Odt1-22<sup>T</sup> contained meso-diaminopimelic acid in peptidoglycan and the whole-cell hydrolysates contained arabinose, galactose, glucose, and ribose. The major menaquinone was MK-8(H<inf>4</inf>). The diagnostic phospholipids were diphosphatidylglycerol, hydroxyphosphatidylethanolamine, phosphatidylethanolamine and phosphatidylglycerol. Phylogenetic analysis based on 16 S rRNA gene sequence revealed that strain Odt1-22<sup>T</sup> was identified to the genus Actinomycetospora and showed high similarity values with A. chiangmaiensis DSM 45062 <sup>T</sup> (99.24%), A. soli SF1<sup>T</sup> (99.24%) and A. corticicola 014-5 <sup>T</sup> (98.17%). The genomic size of strain Odt1-22<sup>T</sup> was 6.6 Mbp with 73.8% G + C content and 6355 coding sequences (CDSs). The genomic analysis, strain Odt1-22<sup>T</sup> and closely related species A. chiangmaiensis DSM 45062 <sup>T</sup>, A. soli SF1<sup>T</sup> and A. corticicola DSM 45772 <sup>T</sup> displayed the values of average nucleotide identity-blast (ANIb) at 83.7–84.1% and MUMmer (ANIm) at 86.6–87.0%. Moreover, the results of digital DNA-DNA hybridization values between strain Odt1-22<sup>T</sup> and related Actinomycetospora species were 45.8−50.5% that lower than the threshold value of commonly used to delineate separated species level. On the basis of phenotypic, chemotaxonomic, and genotypic data, strain Odt1-22<sup>T</sup> represented a novel species within the genus Actinomycetospora, for which the name Actinomycetospora termitidis sp. nov. is proposed. The type strain of the species is Odt1-22<sup>T</sup> (= TBRC 16192 <sup>T</sup> = NBRC 115965 <sup>T</sup>).
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    Comparative genomics reveals insight into the phylogeny and habitat adaptation of novel Amycolatopsis species, an endophytic actinomycete associated with scab lesions on potato tubers
    (2024-01-01)
    Wannawong, Thippawan
    ;
    Mhuantong, Wuttichai
    ;
    Macharoen, Pipat
    ;
    Niemhom, Nantawan
    ;
    Sitdhipol, Jaruwan
    A novel endophytic actinomycete, strain MEP2-6<sup>T</sup>, was isolated from scab tissues of potato tubers collected from Mae Fag Mai Sub-district, San Sai District, Chiang Mai Province, Thailand. Strain MEP2-6<sup>T</sup> is a gram-positive filamentous bacteria characterized by meso-diaminopimelic acid in cell wall peptidoglycan and arabinose, galactose, glucose, and ribose in whole-cell hydrolysates. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and hydroxy-phosphatidylethanolamine were the major phospholipids, of which MK-9(H<inf>6</inf>) was the predominant menaquinone, whereas iso-C<inf>16:0</inf> and iso-C<inf>15:0</inf> were the major cellular fatty acids. The genome of the strain was 10,277,369 bp in size with a G + C content of 71.7%. The 16S rRNA gene phylogenetic and core phylogenomic analyses revealed that strain MEP2-6<sup>T</sup> was closely related to Amycolatopsis lexingtonensis NRRL B-24131<sup>T</sup> (99.4%), A. pretoriensis DSM 44654<sup>T</sup> (99.3%), and A. eburnea GLM-1<sup>T</sup> (98.9%). Notably, strain MEP2-6<sup>T</sup> displayed 91.7%, 91.8%, and 87% ANIb and 49%, 48.8%, and 35.4% dDDH to A. lexingtonensis DSM 44653<sup>T</sup> (=NRRL B-24131<sup>T</sup>), A. eburnea GLM-1<sup>T</sup>, and A. pretoriensis DSM 44654<sup>T</sup>, respectively. Based on phenotypic, chemotaxonomic, and genomic data, strain MEP2-6<sup>T</sup> could be officially assigned to a novel species within the genus Amycolatopsis, for which the name Amycolatopsis solani sp. nov. has been proposed. The type of strain is MEP2-6<sup>T</sup> (=JCM 36309<sup>T</sup> = TBRC 17632<sup>T</sup> = NBRC 116395<sup>T</sup>). Amycolatopsis solani MEP2-6<sup>T</sup> was strongly proven to be a non-phytopathogen of potato scab disease because stunting of seedlings and necrotic lesions on potato tuber slices were not observed, and there were no core biosynthetic genes associated with the BGCs of phytotoxin-inducing scab lesions. Furthermore, comparative genomics can provide a better understanding of the genetic mechanisms that enable A. solani MEP2-6<sup>T</sup> to adapt to the plant endosphere. Importantly, the strain smBGCs accommodated 33 smBGCs encoded for several bioactive compounds, which could be beneficially applied in the fields of agriculture and medicine. Consequently, strain MEP2-6<sup>T</sup> is a promising candidate as a novel biocontrol agent and antibiotic producer.
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    Biocontrol Potential, Genome and Nonribosomal Peptide Synthetase Gene Expression of Bacillus velezensis 2211
    (2023-01-01)
    Niemhom, Nantawan
    ;
    Kittiwongwattana, Chokchai
    Members of the genus Bacillus produced a diverse group of antimicrobial compounds. Here, we presented the antifungal activity and genome sequence analysis of Bacillus sp. 2211, a potential plant-growth-promoting bacterium. Bacterial supernatants from strain 2211 cultures in nutrient broth (NB) and potato dextrose broth (PDB) suppressed the mycelial growth of Pyricularia oryzae, Colletotrichum aenigma, Colletotrichum fructicola and Fusarium oxysporum. The supernatants were also able to suppress spore germination of these fungi, except for F. oxysporum. However, the supernatant from PDB displayed a significantly higher inhibition activity than NB. Additionally, the supernatant from PDB significantly reduced the disease severity caused by P. oryzae on rice seedlings. The genome of strain 2211 was sequenced. The highest digital DNA-DNA hybridization (80.1%) and average nucleotide identity (97.57%) levels indicated that strain 2211 was a member of the species Bacillus velezensis. The phylogenomic analysis showed that it clustered with B. velezensis NRRL B-41580<sup>T</sup>, B. velezensis KACC 13105 and B. velezensis subsp. plantarum FZB42<sup>T</sup>. The gene expression analysis showed the up-regulation of nonribosomal peptide synthetase (NRPS) genes bmyA, fenB and dhbE in PDB, compared to NB. This work demonstrated that the culture media affected the antagonistic activity of strain 2211 possibly through the modification of NRPS biosynthesis genes.
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    Glycomyces amatae sp. nov., isolated from a yellow-ringed grass moth (Amata sperbius)
    (2022-01-01)
    Suriyachadkun, Chanwit
    ;
    Ngaemthao, Wipaporn
    ;
    Pujchakarn, Tawanmol
    ;
    Chamroensaksri, Nitcha
    ;
    Niemhom, Nantawan
    A novel mycelium-forming actinomycete strain, designated A-F 0318<sup>T</sup>, was isolated from a yellow-ringed grass moth (Amata sperbius) collected from Phitsanulok Province, Thailand. Long chains of non-motile cylindrical spores with a smooth surface developed on aerial mycelia. The polyphasic taxonomic study suggested that strain A-F 0318<sup>T</sup> belonged to the genus Glyco-myces. The 16S rRNA gene sequence analysis indicated that strain A-F 0318<sup>T</sup> was closely related to Glycomyces harbinensis LL-DO5139<sup>T</sup> with 97.94 % sequence similarity. The average nucleotide identity (ANI) based on blast, ANI based on the MUMmer algorithm and average amino acid identity values of strain A-F 0318<sup>T</sup> with G. harbinensis LL-DO5139<sup>T</sup> were 86.9, 89.1 and 84.24 %, respectively. The digital DNA–DNA hybridization value between A-F 0318<sup>T</sup> and its closest relative, G. harbinensis LL-DO5139<sup>T</sup> was 33.8 %. The digital G+C content of the genomic DNA was 71.7 mol%. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose, xylose, glucose and galactose. The predominant menaquinone was MK-10(H<inf>4</inf> ). The predominant fatty acids were iso-C<inf>16: 0</inf>, anteiso-C<inf>15: 0</inf>, anteiso-C<inf>17: 0</inf> and iso-C<inf>16: 1</inf> G. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, two unknown phosphoglycolipids and one unknown phospholipid. Based on comparative analysis of genotypic, phenotypic and chemotaxo-nomic data, the novel actinomycete strain A-F 0318<sup>T</sup> (=TBRC 13612<sup>T</sup>=NBRC 115417<sup>T</sup>) represents the type strain of a novel species, for which the name Glycomyces amatae sp. nov. is proposed.
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    Abyssomicin derivatives from the rhizosphere soil actinomycete Microbispora rhizosphaerae sp. nov. TBRC6028
    (2021-05-01)
    Bunbamrung, Nantiya
    ;
    Kittisrisopit, Suchada
    ;
    Intaraudom, Chakapong
    ;
    Dramae, Aibrohim
    ;
    Thawai, Chitti
    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 (<sup>1</sup>H, <sup>13</sup>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.
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    Neuroprotective potential of new chromones isolated from the soil actinomycete Microbispora sp. TBRC6027
    (2021-01-01)
    Kittisrisopit, Suchada
    ;
    Bunbamrung, Nantiya
    ;
    Thawai, Chitti
    ;
    Tadtong, Sarin
    ;
    Niemhom, Nantawan
    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<inf>50</inf> in a range of 87.99–91.57 μM.
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    Chitinophaga oryzae sp. Nov., an epiphytic bacterium isolated from rice root surfaces
    (2021-01-01)
    Niemhom, Nantawan
    ;
    Suriyachadkun, Chanwit
    ;
    Kittiwongwattana, Chokchai
    Two Gram-stain-negative, non-motile, rod-shaped bacterial strains were isolated from the surfaces of rice roots. They were designated as strains 1303<sup>T</sup> and 1310. Their colonies were circular, entire, opaque, convex and yellow. They were chitinaseand catalase-positive, reduced nitrate and grew at 16–37 °C (optimum, 30 °C), pH 5.0–10.0 (optimum, pH 7.0) and 0–2.0% NaCl (optimum, 1.0%). Based on the 16S rRNA gene sequence analysis, they were classified as members of the genus Chitinophaga. Results of phylogenetic and phylogenomic analyses indicated that they formed a cluster with Chitinophaga eiseniae YC6729<sup>T</sup>, Chitinophaga qingshengii JN246<sup>T</sup>, Chitinophaga varians 10-7 W-9003<sup>T</sup> and Chitinophaga fulva G-6-1-13<sup>T</sup>. When the genomic sequences of strains 1303<sup>T</sup> and 1310 were compared with their close relatives, the average nucleotide identity and digital DNA– DNA hybridization values were below the cut-off levels. Phosphatidylethanolamine was the major polar lipid. MK-7 was the major respiratory quinone. iso-C<inf>15:0</inf>, C<inf>16:1</inf> ω5c, iso-C<inf>17:0</inf> 3-OH and summed feature 3 (C<inf>16:1</inf> ω7c/C<inf>16:1</inf> ω6c) were the predominant fatty acids. Differential characteristics between both strains and their close relatives were also observed. Based on the distinctions in genotypic, phenotypic and chemotypic features, strains 1303<sup>T</sup> and 1310 represent members of a novel species of the genus Chitinophaga, for which the name Chitinophaga oryzae sp. nov. is proposed. The type strain is 1303<sup>T</sup> (=KACC 22075<sup>T</sup>=TBRC 12926<sup>T</sup>).