Thawai, Chitti

Preferred name

Thawai, Chitti

Main Affiliation

School of Science

chitti.th@kmitl.ac.th

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Discovery of Streptomyces marinisediminis sp. nov., a new thiolutin producing actinomycete isolated from Thai marine sediment
(2025-12-01)
Pansomsuay, Rawirat
;
Fukasem, Poowadon
;
Pittayakhajonwut, Pattama
;
Intaraudom, Chakapong
;
Suriyachadkun, Chanwit
Thiolutin and 2,2-dioxidothiolutin are sulfur-containing antibiotics discovered through a targeted high-throughput screening strategy designed to identify compounds with antimicrobial activity. The producing strain, JHD1T, is an actinomycete isolated from marine sediment collected in Chonburi Province, Thailand. Chemotaxonomic characteristics and 16S rRNA gene sequence analysis indicated that strain JHD1T belongs to the genus Streptomyces. Taxonomic analysis using a polyphasic approach further supported its placement within the genus Streptomyces. The strain exhibited low similarity to its closest known relatives, Streptomyces alkaliterrae OF1T and Streptomyces chumphonensis KK1-2T, with average nucleotide identity based on MuMmer ultra-rapid aligning tool (ANIm) values of 85.7–86.2%, average amino acid identity (AAI) values of 71.8–78.1%, and digital DNA–DNA hybridization (dDDH) values of 23.4–25.0%, all well below the established thresholds for species delineation. These results reveal that strain JHD1T represents a novel species within the genus Streptomyces, for which the name Streptomyces marinisediminis sp. nov. is proposed. The crude extract obtained from the culture broth of strain JHD1T exhibited strong antimicrobial activity against Gram-positive bacteria and led to the discovery of two promising secondary metabolites, thiolutin and 2,2-dioxidothiolutin, along with 8-amino-2H-benz[e][1,3]oxazine-2,4(3H)-dione, benadrostin, 2,3-dihydroxybenzamide, and 2-hydroxy-3-methoxybenzamide. In this study, 2,2-dioxidothiolutin was structurally confirmed for the first time by X-ray crystallographic analysis. Interestingly, thiolutin demonstrated strong anti-human small cell lung cancer (NCI-H187) activity, with an IC₅₀ value of 0.35 µg/mL, and also showed cytotoxicity against human breast cancer (MCF-7) cells, with an IC₅₀ value of 5.61 µg/mL.
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Salinicoccus siamensis sp. nov., isolated from fermented shrimp paste in Thailand
(2007-09-01)
Pakdeeto, Amnat
;
Tanasupawat, Somboon
;
Thawai, Chitti
;
Moonmangmee, Somporn
;
Kudo, Takuji
Fifteen strains of moderately halophilic, Gram-positive cocci were isolated from a traditional fermented shrimp paste ('ka-pi') produced in Thailand. These bacteria were strictly aerobic, non-motile, non-sporulating and catalase- and oxidase-positive. They produced orange pigment and grew in the presence of 1.5-25% (w/v) NaCl. They grew optimally in 10% (w/v) NaCl, at pH 8.5 and at 37 °C. The cell-wall peptidoglycan was Of L-Lys type. Menaquinone with six isoprene units (MK-6) was a major component. The dominant cellular fatty acids were anteiso-C<inf>15:0</inf> and iso-C<inf>15:0</inf>. DNA G + C contents were in the range 44.5-47.5 mol%. Comparative 16S rRNA gene sequence analyses indicated that representative strain PN 1-2T was related most closely to Salinicoccus roseus JCM 14630T, with 97.3% similarity. The other novel strains were included in the same species based on their levels of DNA-DNA relatedness to strain PN1-2T (≥76.6%) but showed low DNA-DNA relatedness to S. roseus JCM 14630T (21.7%). On the basis of the phenotypic and molecular data presented, the 15 novel strains are suggested to represent a single novel species of the genus Salinicoccus, for which the name Salinicoccus siamensis sp. nov. is proposed. The type strain is PN1-2T (=JCM 12822T =PCU 242T =TISTR 1562T). © 2007 IUMS.
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Dactylosporangium tropicum sp. nov., isolated from soil
(2011-10-01)
Thawai, Chitti
;
Tanasupawat, Somboon
;
Kudo, Takuji
Two novel actinomycete strains, designated KB2-4 T and KB9-2, were isolated from soil samples. Both isolates formed finger-shaped sporangia on short sporangiophores that emerged directly from substrate hyphae. The cell-wall peptidoglycan contained glutamic acid, glycine, alanine and meso-diaminopimelic acid; the whole-cell sugars were galactose, glucose, mannose, rhamnose, ribose and xylose. The diagnostic phospholipid was phosphatidylethanolamine. The predominant menaquinones were MK-9(H8) and MK-9(H6). Mycolic acids were not detected. The predominant cellular fatty acids (>20 %) were iso-C <inf>16: 0</inf> and anteiso-C <inf>17: 0</inf>. For both strains, the G+C content of the genomic DNA was about 72 mol%. The morphological and chemotaxonomic characteristics of the two strains were typical of members of the genus Dactylosporangium. Phylogenetic analysis using 16S rRNA gene sequences also indicated that these strains should be classified in the genus Dactylosporangium and showed that the closest relative was Dactylosporangium salmoneum NRRL B-16294 T (99.1% 16S rRNA gene sequence similarity). DNA-DNA relatedness and some physiological and biochemical properties indicated that the isolates could be readily distinguished from their closest phylogenetic relatives. On the basis of these phenotypic and genotypic data, the isolates represent a novel species, for which the name Dactylosporangium tropicum sp. nov. is proposed. The type strain is strain KB2-4T (=BCC 34760 T =JCM 15673 T). © 2011 IUMS.
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Micromonospora caldifontis sp. nov., isolated from hot spring soil
(2019-05-01)
Thawai, Chitti
;
Tanasupawat, Somboon
;
Kudo, Takuji
A single spore forming actinomycete, designated strain HSS6-8T, was isolated from a sample of hot spring soil. The strain had the chemotaxonomic properties consistent with its classification in the genus Micromonospora. The strain was found to have meso-diaminopimelic acid in the cell-wall peptidoglycan. The acyl type of the cell-wall muramic acid was glycolyl. The reducing sugars in the cell hydrolysates were glucose, arabinose, xylose, ribose, mannose, galactose and rhamnose. The phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphoglycolipid. The major menaquinones were MK-10(H<inf>6</inf>) and MK-10(H<inf>4</inf>). The major cellular fatty acids were iso-C<inf>16: 0</inf>, anteiso-C<inf>17: 0</inf>, C<inf>17: 0 </inf>and anteiso-C<inf>15: 0</inf>. The G+C content of the genomic DNA was 70.5 mol%. 16S rRNA gene sequence analysis revealed that strain HSS6-8T was closely related to Micromonospora nigra DSM 43818T (98.2%), Micromonospora eburnea DSM 44814T (98.2%) and Micromonospora spongicola S3-1T (98.1%). The physiological and DNA-DNA hybridization data allowed the differentiation of strain HSS6-8T from its related species. Thus, the strain represents a novel species of the genus Micromonospora, for which the name Micromonospora caldifontis sp. nov. is proposed. The type strain is HSS6-8T (=TBRC 8927T=JCM 17126T).
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Agromyces tropicus sp. nov., isolated from soil
(2011-03-01)
Thawai, Chitti
;
Tanasupawat, Somboon
;
Suwanborirux, Khanit
;
Kudo, Takuji
Two actinomycete strains, CM9-9T and AK2-48, which produced straight rod-shaped, non-motile cells, were isolated from soils in Chiang Mai and Phuket provinces, respectively, Thailand. The morphological and chemotaxonomic characteristics of the isolates coincided with those of the genus Agromyces. Phylogenetic analysis using 16S rRNA gene sequences also indicated that the isolates were clearly separated from their closest relative, Agromyces aurantiacus YIM 21741T, and should be classified in the genus Agromyces. Furthermore, a combination of DNA - DNA hybridization results and physiological and biochemical properties indicated that the isolates could be distinguished from all recognized members of the genus Agromyces. The isolates therefore represent a novel species, for which the name Agromyces tropicus sp. nov. is proposed. The type strain is CM9-9T (=JCM 15672T =BCC 34764T). © 2011 IUMS Printed in Great Britain.
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Micromonospora spongicola sp. nov., an actinomycete isolated from a marine sponge in the Gulf of Thailand
(2013-09-01)
Supong, Khomsan
;
Suriyachadkun, Chanwit
;
Pittayakhajonwut, Pattama
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Suwanborirux, Khanit
;
Thawai, Chitti
An actinomycete strain, S3-1 T, was isolated from marine sponge sample collected from the Gulf of Thailand. The strain is aerobic, Gram-positive and produced single spores at the tip of the substrate mycelium. Strain S3-1 T contained meso-diaminopimelic acid in the peptidoglycan, whole-cell sugars were arabinose, galactose, glucose, rhamnose, ribose and xylose. The polar lipid profile of strain S3-1 T consisted of phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides, phosphoglycolipid and unknown polar lipids. Morphological and chemotaxonomic characteristics of the strain were identified as a member of the genus Micromonospora. Phylogenetic analysis based on 16S rRNA gene sequence analysis of the strain showed similarity to Micromonospora nigra DSM 43818 T (98.8%), Micromonospora yangpuensis FXJ6.011 T (98.7%) and Micromonospora narathiwatensis BTG4-1 T (98.6%). The DNA G+C content was 72.7 mol%. The phenotypic characteristics and DNA-DNA relatedness values supported that the classification of this strain as a novel species in the genus Micromonospora, for which the name Micromonospora spongicola sp. nov. (type strain S3-1 T =BCC 45595 T =NBRC 108779 T) is proposed. © 2013 Japan Antibiotics Research Association All rights reserved.
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Asanoa siamensis sp. nov., isolated from soil from a temperate peat swamp forest
(2013-01-23)
Niemhom, Nantawan
;
Suriyachadkun, Chanwit
;
Tamura, Tomohiko
;
Thawai, Chitti
A novel actinomycete strain, PS7-2T, which produced spore chains borne on the tips of short sporophores, was isolated from soil collected from a temperate peat swamp forest in Phu-Sang National Park, Phayao province, Thailand. The isolate contained glutamic acid, glycine, alanine, 3-hydroxy-diaminopimelic acid and meso-diaminopimelic acid in the cell-wall peptidoglycan. The whole-cell sugars were glucose, mannose, rhamnose and xylose, and the major phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylethanolamine. The predominant menaquinones were MK-10(H<inf>8</inf>) and MK-9(H<inf>8</inf>) and the predominant cellular fatty acids were iso-C<inf>15: 0</inf>, anteiso-C<inf>15: 0</inf> and anteiso-C<inf>17: 0</inf>. The G+C content of the genomic DNA was 72.3 mol%. On the basis of 16S rRNA gene sequence analysis, strain PS7-2T clustered with members of the genus Asanoa and appeared most closely related to the type strains of Asanoa hainanensis (99.5% sequence similarity), Asanoa iriomotensis (99.0%), Asanoa ishikariensis (98.9%) and Asanoa ferruginea (98.5%). DNA-DNA hybridiza-tions and some physiological and biochemical properties indicated that strain PS7-2T could be readily distinguished from its closest phylogenetic relatives. Based on the phenotypic and genotypic evidence and DNA-DNA relatedness values, strain PS7-2T represents a novel species in the genus Asanoa, for which the name Asanoa siamensis sp. nov. is proposed; the type strain is PS7-2T (5BCC 41921T5NBRC 107932T). © 2013 IUMS.
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Actinocatenispora thailandica gen. nov., sp. nov., a new member of the family Micromonosporaceae
(2006-08-01)
Thawai, Chitti
;
Tanasupawat, Somboon
;
Itoh, Takashi
;
Kudo, Takuji
Two actinomycete strains, TT2-10T and TT2-3, which produced long spore chains (more than 10 spores per chain), were isolated from peat swamp forest soil in Pattaloong Province, Thailand. Their taxonomic positions were determined using a polyphasic approach. The chemotaxonomic characteristics of these strains coincided with those of the family Micromonosporaceae, i.e. cell-wall chemotype II, muramic acid of the N-glycolyl type, whole-cell sugar pattern D and type II phospholipids. Analysis of the 16S rRNA gene sequences also indicated that these strains constitute a distinct lineage within the family Micromonosporaceae, sharing 91.3-93.8 % sequence similarity with members of this family. On the basis of their phenotypic and genotypic characteristics and their phylogenetic position, these strains represent a novel genus and species, for which the name Actinocatenispora thailandica gen. nov., sp. nov. is proposed. The type strain of Actinocatenispora thailandica is strain TT2-10T (=JCM 12343T=PCU 235T=DSM 44816T). © 2006 IUMS.
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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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Antibacterial, antitubercular, antimalarial and cytotoxic substances from the endophytic Streptomyces sp. TBRC7642
(2020-04-01)
Bunbamrung, Nantiya
;
Intaraudom, Chakapong
;
Dramae, Aibrohim
;
Thawai, Chitti
;
Tadtong, Sarin
Eight previously undescribed naturally-occurring compounds, including abyssomycins Y - Z, methyl aeruginoate, desferri-ferrithocin-4-hydroxyphenethylester, streptomethiocins A - B, furaquinocin I, and streptolactone, along with eleven known compounds were isolated from the endophytic Streptomyces sp. TBRC7642. The chemical structures were determined based on spectroscopic means including 1D, 2D NMR spectroscopy and mass spectrometry. The absolute configurations were assigned by relying on CD spectra and their optical rotations. In addition, the isolated compounds were evaluated for biological activity, such as antimalarial, antitubercular, antibacterial (both Gram-positive and Gram-negative bacteria), as well as for cytotoxicity against MCF-7, NCI–H187, and Vero cells.

Thawai, Chitti

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