Klanbut, Khanungkan

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Klanbut, Khanungkan
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Email
khanungkan.kl@kmitl.ac.th

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    Item type:Publication,
    Streptomyces tyrfis sp. nov., an actinobacterium isolated from Thai peat swamp forest soil and its promising secondary metabolites
    (2026-12-01)
    Kottip, Penkawee
    ;
    Klanbut, Khanungkan
    ;
    Fukasem, Poowadon
    ;
    Pittayakhajonwut, Pattama
    ;
    Intaraudom, Chakapong
    An actinomycete strain, PTD5-9<sup>T</sup>, was isolated from peat swamp forest soil in Narathiwat Province, Thailand. Chemotaxonomic features and phylogenetic analysis based on the 16S rRNA gene sequence placed this strain within the genus Streptomyces. It exhibited the highest sequence similarity to Streptomyces gelaticus NRRL B-2928ᵀ (99.38%) and Streptomyces sanglieri NBRC 100784ᵀ (99.31%). However, the average nucleotide identity based on MUMmer (ANIm) values (88.48–88.56%), the average amino acid identity (84.37–84.97%), and digital DNA–DNA hybridization (dDDH) estimates (31.2–36.5%) were significantly below the accepted thresholds for species demarcation, supporting its classification as a new species within the genus. Accordingly, the name Streptomyces tyrfis sp. nov. is proposed. The crude extract derived from the culture broth of strain PTD5-9ᵀ exhibited potent antibacterial activity against Gram-positive bacteria (MIC ≤ 250 µg/mL). Subsequent chemical analysis led to the identification of ten bioactive secondary metabolites: isocycloheximide (1), (2R,4S,6E)-anhydrocycloheximide (2), actiphenol (3), (−)-phenatic acid A (4), 8-O-methyltetrangomycin (5), 8-O-methylrabelomycin (6), 4-hydroxy-8-O-methylrabelomycin (7), tetrangulol methyl ether (also known as X-14881 E) (8), (−)-elmonin (9), and 2-phenylacetamide (10). Among these, compounds 3, 6, 7, and 8, which were isolated in sufficient quantities, exhibited notable inhibitory activity against Mycobacterium tuberculosis, with MIC values ranging from 3.13 to 25.0 µg/mL. Furthermore, compounds 6, 7, and 8 demonstrated pronounced cytotoxicity against human small cell lung cancer (NCI-H187) cells (IC₅₀: 1.10–7.80 µM), and against human breast cancer (MCF-7) cells (IC₅₀: 1.21–24.6 µM).
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    Nocardia xestospongiae sp. nov., isolated from a marine sponge in the Andaman sea
    (2017-05-01)
    Thawai, Chitti
    ;
    Rungjindamai, Nattawut
    ;
    Klanbut, Khanungkan
    ;
    Tanasupawat, Somboon
    A marine sponge-derived actinomycete, strain ST01-07<sup>T</sup>, was isolated from Xestospongia sp. collected from the Andaman Sea. The strain was characterised taxonomically using a polyphasic approach. The strain contained meso-diaminopimelic acid in the peptidoglycan, whole-cell sugars were arabinose, galactose, glucose, mannose and ribose. Mycolic acids that co-migrated with those from Nocardia araoensis NBRC 100135<sup>T</sup> were observed in whole-cell extracts. MK-8(H<inf>4ω-cycl</inf>) was the predominant menaquinone. Major cellular fatty acids were C<inf>17: 1</inf>ω8c, C<inf>16: 0</inf> and C<inf>17: 0</inf>. The diagnostic phospholipids in the cell consisted of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain ST01-07<sup>T</sup> belonged to the genus Nocardia and was most closely related to N. araoensis IFM 0575<sup>T</sup> (98.71% 16S rRNA gene sequence similarity), Nocardia niwae W9241<sup>T</sup> (98.56%), Nocardia beijingensis AS4.1521<sup>T</sup> (98.41%) and Nocardia arthritidis IFM 10035<sup>T</sup> (98.36%). In addition, low DNA–DNA relatedness values (13.6±0.1% to 40.1±0.6%) confirmed that strain ST01-07<sup>T</sup> represents a novel species of the genus Nocardia, for which the name Nocardia xestospongiae sp. nov., is proposed. The type strain is ST01-07<sup>T</sup> (=BCC 45622<sup>T</sup>=NBRC 109069<sup>T</sup>).