More than 100 actinomycetes colonies were isolated from 12 soil samples of the Nam Cat Tien National Park and Cam Ranh Ecopark in Vietnam. Among them, 41 actinomycetes strains with different colony characteristics (i.e. color, size, aerial and substrate mycelia formation, secretion of pigment in the culture medium...) were cultured in the L4 medium for HPLC analysis. The result has showed that only 23 strains can synthesis bioactive natural products. 8 among 23 strains were selected depending on HPLC analysis such as 5-37a, Tr-41.2, 8-54, S-57,S-61, S-68, Tr-73.26, S-91 for assay to determine bioactivity. The result has showed that most of them were bioactive against gram-positive bacteria (Bacillus subtilis, Streptomyces sp.), but not for gram- negative bacteria (Escherichia call)
one strain was tolerant mold (Penicillium sp.), and other one was tolerant yeast (Saccharomyces cerevisae). The name of these species was identified based on morphology and molecular information on the 165-rRNA region. The results have indicated that S-61 was named Streptomyces galbus and S-91 was Streptomyces pulveraceus. S-54 strain should be studied in more detail with expectation of a species for science.