Isolation and Characterization of a novel Streptomycetes, Streptomyces banglaensis from Bangladeshi Soil
Creators: name: Sharmin, Tahmida
Publisher: name: Zenodo
Year: 2011

description: With an aim to isolate novel actinomycetes having antimicrobial and cytotoxic properties, five colonies of actinomycetes were isolated from the soils collected from the different locations of Rajshahi District, Bangladesh and designated as ANTS-1 to ANTS-5. Among them ANTS-1 and ANTS-5 were selected for taxonomic characterization and identification due to their antagonistic activity against a series of test organisms. The taxonomic positions of the actinomycetes, ANTS-1 and ANTS-5 were clarified using a polyphasic approach. The strains were assigned to the genus<em> Streptomyces </em>based on their phenotypic and cultural characteristics. A partial sequence of 16S rDNA of the strain ANTS-1 was determined and compared with other <em>Streptomyces </em>species in the NCBI database. Phylogenetic analysis based on partial 16S rDNA sequence indicated that strain ANTS-1 was most closely related to <em>Streptomyces griseoplanus</em> NBRC 12779 (98.93%), <em>Kitasatospora arboriphila </em>HKI 0189 (97.35%) and<em> Streptomyces paucisporeus </em>1413 (97.35%). However, the phenotypic properties and the nature of secondary metabolite produced by the strain ANTS- 1 differed from closely related species of <em>Streptomyces</em>. Thus, the strain ANTS-1 is considered to represent a novel species of the genus <em>Streptomyces</em>, for which the name <em>Streptomyces banglaensis</em> (GenBank accession JF812169) sp. nov. is proposed. The strain ANTS-5 (GenBank accession JF812170) was identified as <em>Streptomyces </em><em>coelicolor</em> (100%) based on the BLAST search of its 16S rDNA sequence and DNA homology experiment of the forward sequence. The crude ethyl acetate extract obtained from the yeast-extract glucose agar (YEGA) medium showed strong activity against pathogenic bacteria and moderate activity against fungi. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the extract against the test bacteria were in the range of 1-2 µg/ml and 4-8 µg/ml, respectively. The LC<sub>50</sub> value of the crude extract against brine-shrimp nauplii was only 0.4µg/ml indicating its potent cytotoxic activity. Further, potato disc antitumor bioassay was carried out at concentrations 0.025mg and 0.0125mg and no tumor growth was visible in these concentrations and consequently ensuring its strong antitumor property. However, three active compounds AS-1, AS-2 and AS-3 were isolated from the fermentation broth of the strain ANTS-1. But less activity was observed from AS-1 and AS-2 than AS-3 which was later identified as Actinomycin D based on comparison of its <sup>1</sup>H-NMR and <sup>13</sup>C-NMR with a <sup>1</sup>H-NMR of authentic Actinomycin D. The <sup>1</sup>H-NMR spectrum of AS-1 and AS-2 could not be interpreted due to the existing impurities. This study indicates that new strains of <em>Streptomyces</em> are available in the soil of Bangladesh and extensive research in this field may discover novel <em>Streptomyces </em>species producing pharmaceutically important bioactive compounds.