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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 M1463 (99.85 %) and Streptomyces malaysiensis NBRC 16446 (99.40 %)]. The crude extract exhibited antimalarial against Plasmodium falciparum (IC 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 (IC 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.

An actinomycete strain, SP03-05 T , was isolated from a marine sponge sample (Xestospongia sp.) collected from Phuket Province of Thailand. The strain was aerobic, Gram-stain-positive and produced single spores at the tips of the substrate mycelium. Strain SP03-05 T contained mesodiaminopimelic acid in the peptidoglycan; whole-cell sugars were arabinose, galactose, glucose, rhamnose, ribose and xylose.

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.

An actinomycete strain, designated strain SH2-13 T , was isolated from a marine sediment sample collected from the Andaman Sea of Thailand. Applying a polyphasic approach, the isolate was identified as a member of the genus Micromonospora using morphological and chemotaxonomic characteristics, including the presence of meso-diaminopimelic acid in the peptidoglycan. Wholecell sugars were arabinose, galactose, glucose, rhamnose, ribose and xylose. Diagnostic polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides and phosphoglycolipids. The major menaquinones were MK-10(H 2 ), MK-10(H 4 ) and

Nonomuraea rhodomycinica NR4-ASC07 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 (IC) of 8.00 and 8.88 μg mL, respectively. Compound 4 inhibited growth of Mycobacterium tuberculosis and Bacillus cereus at the minimum inhibitory concentrations of 50.0 and 12.50 μg mL, respectively. Every compound exhibited cytotoxicity against cancer cells tested at IC ≥ 6.34 μg mL. These finding are the first report of bioactive metabolites produced by strain NR4-ASC07, suggesting that rare actinomycetes are yet promising sources for novel drug discovery.