Showing 4 results for Streptomyces
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Volume 3, Issue 1 (11-2012)
Abstract
Gold nanoparticles have received considerable attention in recent years because of their promising applications in diagnostic imaging, biosensors, biolabels, and drug and gene delivery systems. The chemical methods of nanoparticle synthesis are the most widely and traditionally used methods. Production of nanoparticles by chemical methods causes contamination from precursor chemicals due to the use of toxic solvents and generation of hazardous by-products. On the other hand, the physical methods have low yield and high cost. Hence, there is an increasing need to develop low cost, non-toxic, biocompatible and environmentally benign processes for synthesis of metallic nanoparticles where the biological approaches for synthesis of nanoparticles gain importance. In this study, we investigated the biosynthesis of gold nanoparticles using Streptomyces sp. ERI-3. Streptomycessp.ERI-3 was isolated from the soil of Ahar Copper Mine (Ahar, Iran) and its biomass was incubated at 28ºC on a rotary shaker (200 rpm) for 48 h. The nanoparticles were characterized by means of UV-vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM).The nanoparticles exhibited maximum absorbance at 540 nm (special wavelength of gold nanoparticles) in UV-vis spectroscopy. The XRD spectrum of gold nanoparticles exhibited 2Ө values corresponding to the gold nanocrystals. The TEM micrographs revealed the extracellular and attached to cell surface formation of gold nanoparticles in the size range of 50-100 nm with spherical morphology.
Volume 7, Issue 4 (11-2021)
Abstract
Backgrounds: Streptomyces is an aerobic filamentous Gram-positive bacterium frequently found in various environments worldwide. Cellulases are a group of glycosyl hydrolase enzymes that are frequently produced by bacteria. Thus, the aim of this study was to detect cellulase-encoding gene (celA) in soil-living Streptomyces strains and evaluate its cloning in Escherichia coli Origami strain.
Materials & Methods: Soil samples were collected from a depth of 5-10 cm in Tehran, Iran. After identification of Streptomyces isolates by morphological and biochemical tests, genomic DNA was extracted. Polymerase chain reaction (PCR) test was employed to identify Streptomyces strains harboring the cellulase gene. The celA gene was positively transmitted to the host bacterium E. coli via a vector and cloned through the TA technique. Real-time PCR was used to measure the overexpression of this gene. ClustalX and Mega5 software were used to draw the phylogenetic tree.
Findings: Out of 12 Streptomyces isolates, 25% were found to carry the celA gene. After cloning the celA gene, the cloned strains were chosen by colony selection (blue/white). The real-time PCR test showed the expression of the celA gene in the transformed strains. Phylogenetic analysis results using the neighbor-joining assay showed that Streptomyces spp. with 81% bootstrap were located in the same clade, indicating their close relatedness.
Conclusion: Soil is one of the high-potential sources of the production of secondary metabolites, which could be used as a valuable source of various biological products such as cellulase.
Volume 9, Issue 1 (3-2023)
Abstract
Backgrounds: This study was conducted with the aim of isolation and molecular identification of Streptomyces spp. producing antibacterial compounds from Iranian soil.
Materials & Methods: In this study, 50 soil samples were collected from different areas of Sanandaj city. Soil samples were cultured on starch casein media. Streptomyces species were characterized using morphological and biochemical assays. Molecular identification was performed by 16S rRNA sequencing. Antimicrobial activity was evaluated using perpendicular streak and agar well diffusion methods.
Findings: To identify active Streptomyces strains in terms of producing antibacterial agents, screening was performed in two stages. Among 20 Streptomyces strains isolated from soil samples, six isolates were selected in the primary screening stage based on their ability to limit the growth of pathogens. Of the two solvents used in the secondary screening stage, ethyl acetate was the most suitable solvent for extracting effective metabolites of Streptomyces. Among the six isolates selected based on their antimicrobial activity, two isolates with the highest antibacterial activity were selected for the sequencing process. By analyzing the dendrogram and the data obtained from the NCBI database, it was found that one isolate (Yellow 4A) was 98% similar to S. fradiae, and the other isolate (Green 4A) was 98% similar to S. coelicolor.
Conclusion: The use of proper strategies to identify potential new Streptomyces species with antibacterial properties may bring a bright future in the treatment of resistant pathogens. However, more studies are required to detect active metabolites of the mentioned isolates.
E. Karimi , A. Sadeghi,
Volume 10, Issue 1 (3-2019)
Abstract
Silver nanoparticles have antimicrobial activity and are used in various commercially produced products. In this study, the effects of two types of nanosilver formulations, including LS2000 and L2000 on two strains of Streptomyces and three phytopathogenic agents, Pythium aphanidermatum, Pythium ultimum and Fusarium solani were investigated. Streptomyces and phytopathogenic agents were cultured on ISP2 and PDA medium respectively supplemented with 0, 5, 10, 25, 50 and 70ppm of LS2000 and L2000. The influence of LS2000 and L2000 on mycelium of Streptomyces was investigated by atomic force microscopy (AFM). Colony forming unit (cfu) of the bacteria decreased in response to elevated concentrations of L2000. LS2000 completely inhibited growth of both strains at a concentration of 5ppm. The inhibitory effects of LS2000 on the phytopathogenic agents were more than L2000. P. aphanidermatum showed the highest tolerance to L2000 and only at 75ppm of the nanoparticles, the diameter of the colonies was decreased. High susceptibility of F. solani to L2000 caused a decrease in fungal colony diameter in lowest concentration of the nanoparticles. The growth of all phytopathogenic agents was decreased by LS2000 and completely stopped in a concentration of 50ppm. The results showed that LS2000 destroyed mycelial networks of the both bacteria in all tested concentrations. Vesicles appeared on the surface of the mycelium branches, subsequent to treatment with L2000. Based on the results, the inhibitory effects of silver nanoparticles on the beneficial soil bacteria were more than on the phytopathogenic agents. Therefore, more caution should be taken in using silver nanoparticles as a fungicide in agriculture.
