Streptomyces osmaniensis sp. nov., isolated from soil

Mechanism-Based Approach to New Antibiotic Producers Screening among Actinomycetes in the Course of the Citizen Science Project

Since the discovery of streptomycin, actinomycetes have been a useful source for new antibiotics, but there have been diminishing rates of new finds since the 1960s. The decreasing probability of identifying new active agents led to reduced interest in soil bacteria as a source for new antibiotics. At the same time, actinomycetes remain a promising reservoir for new active molecules. In this work, we present several reporter plasmids encoding visible fluorescent protein genes. These plasmids provide primary information about the action mechanism of antimicrobial agents at an early stage of screening. The reporters and the pipeline described have been optimized and designed to employ citizen scientists without specialized skills or equipment with the aim of essentially crowdsourcing the search for new antibiotic producers in the vast natural reservoir of soil bacteria. The combination of mechanism-based approaches and citizen science has proved its effectiveness in practice, revealing a significant increase in the screening rate. As a proof of concept, two new strains, Streptomyces sp. KB-1 and BV113, were found to produce the antibiotics pikromycin and chartreusin, respectively, demonstrating the efficiency of the pipeline.

Characterization and phylogenetic analysis of antituberculous compound producing actinomycete strain D25 isolated from Thar Desert soil, Rajasthan

During the course of the anti-infective drug discovery programme, actinomycete strain D25 was recovered from the Thar Desert soil, Rajasthan, India. Actinomycin type of compound isolated from the strain D25 showed promising activity against multi drug resistant and extensively drug resistant M. tuberculosis isolates. The present study reports the characteristics and phylogenetic status of the actinomycete strain D25. Phenotypic and cell wall characteristics revealed that the strain belongs to the genus Streptomyces. Further 16s rRNA analysis confined the genus Streptomyces with 97% similarity to the closely related species Streptomyces althioticus KCTC 9752. The 16s rRNA sequence was submitted to GenBank with the accession number JN604533.1. According to Bossard et al. (2003) strain D25 was found to be a novel species of the genus Streptomyces from Thar Desert soil, Rajasthan.

Streptomyces endophyticus sp. nov., an endophytic actinomycete isolated from Artemisia annua L

Three filamentous actinomycetes, strains YIM 65594(T), YIM 65638 and YIM 65642, were isolated from the surface-sterilized roots of Artemisia annua L. collected from Yunnan province, south-west China. These strains were found to have morphological and chemotaxonomic characteristics typical of the genus Streptomyces. The organisms formed an extensively branched substrate mycelium, with abundant aerial hyphae that differentiated into spores. The cell wall of the isolates contained ll-diaminopimelic acid and the menaquinones were MK-9(H(8)) and MK-9(H(6)). The major fatty acids were anteiso-C(15 : 0), anteiso-C(17 : 0) and iso-C(16 : 0). Phylogenetic analysis of the 16S rRNA gene sequences of these strains revealed that the strains clustered together and were most closely related to Streptomyces kunmingensis NBRC 14463(T), with 98.5-98.6 % 16S rRNA gene sequence similarity. The results of DNA-DNA hybridization and physiological tests allowed the genotypic and phenotypic differentiation of strains YIM 65594(T), YIM 65638 and YIM 65642 from related species. However, the high level of DNA-DNA relatedness between them showed that these three strains belong to the same species. Strain YIM 65594(T) (= DSM 41984(T) = CCTCC AA 209036(T)) was selected as the type strain to represent this novel species, for which the name Streptomyces endophyticus sp. nov. is proposed.

Streptomyces hyderabadensis sp. nov., an actinomycete isolated from soil

A novel actinomycete, designated strain OU-40(T), was isolated from farm soil collected from the Hyderabad region of Andhra Pradesh, southern India. The strain was found to have morphological and chemotaxonomic characteristics typical of species of the genus Streptomyces. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain OU-40(T) belonged to the genus Streptomyces, and was related most closely to Streptomyces pactum NBRC 13433(T) (99.0 % sequence similarity), Streptomyces olivaceus NBRC 12805(T) (99.0 %) and Streptomyces parvulus NBRC 13193(T) (98.8 %). Strain OU-40(T) could be distinguished from the type strains of its closest phylogenetic relatives based on levels of DNA-DNA relatedness and comparison of morphological and phenotypic data. It is therefore concluded that strain OU-40(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces hyderabadensis sp. nov. is proposed. The type strain is OU-40(T) (=CCTCC AA 209024(T) =PCM 2692(T)).