Antibiotic production is a key area in biotechnology. To enhance the productivity and improve the economics, much attention has been paid on the improvement of the factors employed in the antibiotic production. Neomycin is an important aminoglycoside antibiotic used widely in pharmaceutical preparations. In this project, Neomycin production by Streptomyces fradiae was studied. Effective factors include: the composition of culture (starch media due to high polysaccharide carbon resource was selected), optimized pH of 7, temperature of 30°C shaking conditions was selected 150 rpm for 72 hr in electrical shaker or 400 rpm with 0.5 VVM air flux for 144 hr in 5 lit fermentor, the optimized production was 3760 mg/lit. Statistic Taguchi method was employed to optimize the production conditions. Results show that the media composition (soybean meal; MgSO4.7H2O; and starch) and pH were the most effective factors in production of Neomycin antibiotic.

The present study aimed to isolate the bacterial strain Streptomyces fradiae from soil and screen it for its ability to biosynthesize PtNPs and characterize and evaluate the antibacterial potential of the manufactured PtNPs. Streptomyces fradiae was isolated from soil samples using the serial dilution method. The isolated bacteria were identified using a light microscope, then diagnosed by biochemical examinations, and lastly by the Polymerase chain reaction (PCR) for molecular diagnostics. The results confirmed the presence of Streptomyces fradiae depending on the amplification of 16s RNA fragments. That was followed by the bacterial screening to examine their ability for use in the production of platinum nanoparticles. The formation of biogenic platinum nanoparticles was confirmed by physical characterization for example UV-VIS spectrophotometer exposed the presence of UV spectrophotometer peak in wavelengths at 362 nm. The results of (TEM) in the electron transmission microscope exposed that the biogenic platinum NPs were in sizes between (2.44-29.57) nm. The field emission scanning microscope also exhibited the examination of surface morphology, shape, and size, where the average diameter for PtNPs was calculated and the final value for this diameter was 5.55 nm. The Zeta potential analyses showed that platinum nanoparticles gained negative surface charges at -28.6 mV. The antibacterial activity of the platinum nanoparticles was evaluated against pathogenic bacteria, there were five species isolated from the hospital, and they exhibited an inhibitory effect on the tested bacterial isolates.

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.

Blakeslea trispora. a filamentous fungus. Was cultured with or without accompanying strains of Micrococcus luteus. Bacillus subtilis, Streptomyces fradiae. And Saccharomyces cerevisiae which were added separately to 24 h old cultures. in order to increase beta-carotene production. It was shown that by adding M. luteus. the β-carotene production in the culture medium was increased about 2.7 times -in comparison to control. B. subtilis and S. fradiae showed no considerable effect on β -carotene production while S. cerevisiae had a negative effect. M. luteus was then added to unmated plus and minus types of B. trispora leading to a little increase in beta- carotene production compared to the control. The positive effect of adding M. luteus was only due to the existence of its life cells. Since addition of autoclaved or cell-free culture supernatant of this bacterium did not increase the beta-carotene production in B. trispora cultures.

Seven strains of Streptomyces obtained from soil surrounding the roots of capsicum ‎were evaluated in vitro and in the greenhouse as potential biological control agents of ‎pink- rot of potato and root and stem rot of tomato. Cell - free metabolites of all ‎strains of Streptomyces inhibited growth of the pathogen, Phytophthora ‎erythroseptica, in vitro. The lesion size on Pontiac potato plant in treatment P. ‎erythroseptica +mixing of all Streptomyces strains (13.25mm) was significantly less ‎than that of P.erythroseptica only (54.75uun). The yields of tubers from Pontiac plants ‎treated with P.erythroseptica and combined Streptomyces isolates (mean of 1(.5 g ‎fresh weight/pot) were significantly greater than in controls inoculated with the ‎pathogen alone (mean of 6.77 g/pot). Control of damping-of of tomato was achieved ‎by inoculating potting mix with Streptomyces strain S2 at the time of planting in a ‎greenhouse‏.‏

Aim and Background: Lincomycin is one of the licozamid compounds. The aim of this study is optimization of lincomycin production using one-factor-at-a-time-method and antimicrobial activity of this antibiotic by Streptomyceslincolenesis PTCC 1629.Material and methods: At first different inorganic and organic carbon and nitrogen sources such as glucose, sucrose, lactose, maltose, fructose, potassium nitrate, sodium nitrate, ammonium sulfate, KH2PO4, CaCl2, CaCo3 were optimized for lincomycin production using one-factor-at-a-time method.Then antimicrobial activity assessed on refrence strains.Results: The results showed that glucose, potassium nitrate were the best carbon and nitrogen sources for lincomycin production by Streptomyceslincolenesis PTCC 1629. Also, the obtained results showed that gram positive strains were sensitive to lincomycin produced by this strain, but gram negative strains were resistant.Conclusion: The obtained results showed that glucose in preculture and production media was the best carbon source for lincomycin production. The best pH and temperature for lincomycin production were 2/78/6 - and 30-28°C, respectively.