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Actinobacteria produce a broad spectrum of bioactive substances that are used in the pharmaceutical, agricultural, and biotechnology industries. This study investigates the production of bioactive substances in <i>Streptomyces</i>, isolated from soil under five tropical plants, focusing on their potential as natural antibacterial dyes for silk fabrics. Out of 194 isolates, 44 produced pigments on broken rice as a solid substrate culture. Eight antibacterial pigmented isolates from under <i>Magnolia baillonii</i> (TBRC 15924, TBRC 15927, TBRC 15931), <i>Magnolia rajaniana</i> (TBRC 15925, TBRC 15926, TBRC 15928, TBRC 15930), and <i>Cinnamomum parthenoxylon</i> (TBRC 15929) were studied in more detail. TBRC 15927 was the only isolate where all the crude extracts inhibited the growth of the test organisms, <i>Staphylococcus epidermidis</i> TISTR 518 and <i>S. aureus</i> DMST 4745. The bioactive compounds present in TBRC 15927 were identified through LC-MS/MS analysis as belonging to the actinomycin group, actinomycin D (or X₁), X₂, and X_0β. Also, the ethyl acetate crude extract exhibited non-toxicity at an IC₅₀ value of 0.029 ± 0.008 µg/mL on the mouse fibroblast L-929 assay. From the 16S rRNA gene sequence analysis, TBRC 15927 had 100% identity with <i>Streptomyces gramineus</i> JR-43^T. Raw silk dyed with the positive antimicrobial TBRC 15927 extract (8.35 mg/mL) had significant (>99.99%) antibacterial properties. <i>Streptomyces gramineus</i> TBRC 15927 is the first actinomycin-producing strain reported to grow on broken rice and shows promise for antibacterial silk dyeing.