Synthesis of some new thiazole derivatives. antifungal activity and ultrastructure changes of some mycotoxin producing fungi.

Several new thiazoles 2-7,10-12; 2,3-diphenyl-5-(2-thienyl)imidazo[2,1-b]thiazole 8, 3,5-di-(2-thienyl)imidazo[2,1-b]thiazole 9 and 4-amino-2-imino-6-(2-thienyl)thiazolo[3,2-a] pyrimidine 13 and 6-(2-thienyl)-3H-thiazolo[3,2-a]pyrimidin-2,4-diones 14 have been synthesized. The prepared compounds were evaluated for their in-vitro antifungal activity, compared with Tioconazol fungicide. The strong antifungal activity is elicited by compounds 5 and 8. The most active compound 5 was found to induce changes in the ultrastructure of mycotoxin producing fungi (Aspergillus flavus and Aspergillus ochraceus), this was observed by both scanning and transmission electron microscopy.

Marine Streptomyces cyaneus Strain Alex-SK121 Mediated Eco-friendly Synthesis of Silver Nanoparticles Using Gamma Radiation.

Aim: The present study aimed to develop cost-effective, eco-friendly marine Streptomyces cyaneus strain Alex-SK121 mediated synthesis of silver nanoparticles (AgNPs) with antimicrobial, antitumor and antioxidant activities. Methodology: Aqueous 1mM silver nitrate (AgNO3) solution was treated with cell-free supernatant (CFS) of a novel Streptomyces cyaneus strain Alex-SK121 isolated from marine sediment samples. The prepared solution was irradiated with different doses of gamma rays ranged from 0.5 to 30.0kGy. Initial characterization of the synthesized AgNPs was performed by visual observation of color change in the prepared solution followed by analysis of UV-Visible Spectrophotometer (UV-Vis.), Fourier Transform Infrared Spectrometer (FT-IR), Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). Evaluation of antimicrobial activity of the synthesized AgNPs against some pathogenic microorganisms was carried out. Antitumor activity of AgNPs was carried out against some human cancer cell lines using the method of Sulphorodamine B (SRB) assay, antioxidant activity of AgNPs was also studied using DPPH scavenging assay. Results: In the present study, the cell-free supernatant of Streptomyces cyaneus strain Alex-SK121 isolated from sediment samples collected from Sidi Kerir region, Alexandria governorate, Egypt was found to reduce Ag+ ions to AgNPs. Identification of the producer strain was performed according to spore morphology and cell wall chemo-type, which suggested that this strain is Streptomyces. Further cultural, physiological characteristics and analysis of the nucleotide sequence of 16S rRNA gene indicated that this strain is identical to Streptomyces cyaneus and then designated Streptomyces cyaneus strain Alex-SK121. To maximize the production of AgNPs, the tested supernatant was irradiated with different doses of gamma rays and it was found that, 15 kGy is the best applied dose induces AgNPs synthesis. The synthesized AgNPs showed the characteristic absorption spectra in UV–Vis. at 425 nm. The microbiologically synthesized AgNPs showed significant antimicrobial activity towards some pathogenic microorganisms with inhibition zone ranged from 13 up to 20 mm. Also AgNPs exhibited antitumor activity against human breast carcinoma cells and human liver carcinoma cells with IC50 9.63 and 33.75 μg/ml respectively in addition to 96% antioxidant activity. Conclusion: Gamma irradiation which induced AgNPs synthesis by cell-free supernatant of marine actinomycetes Streptomyces cyaneus strain Alex-SK121 with different applications is a simple, clean, economic and environmental friendly approach.

Synthesis of Selenium Nanoparticles by Bacillus laterosporus Using Gamma Radiation.

Aim: This study shows the possible synthesis of Selenium Nanoparticles (SeNPs) in aerobic optimized conditions using Bacillus laterosporus (B. laterosporus) bacterial strain. Methodology: B. laterosporus was used to reduce selenium ions (selenite anions) to SeNPs by fermentation in Luria-Bertani Enrichment (EM) medium. Optimization of fermentation conditions using two-level full factorial design was performed. SeNPs were further characterized by UV-Vis., DLS, TEM, FT-IR, EDX and XRD analysis. SeNPs synthesis by Gamma irradiated B. laterosporus cells at different radiation doses was reported. Evaluation the probability of B. laterosporus to synthesis SeNPs by fermentation in skimmed milk aerobically. A microtiterplate assay was used to evaluate the ability of SeNPs to inhibit the biofilm formation of Pseudomonas aeruginosa. Evaluating the antimicrobial activity of some antibiotic agents upon addition of SeNPs was performed. Results: B. laterosporus reduced the soluble, toxic, colorless selenium ions to the insoluble, non-toxic, red elemental SeNPs. Statistical analysis showed that the results were normally distributed. Temperature, incubation period and pH were significant factors in the fermentation process, in which the maximum SeNPs produced (8.37μmole/ml) was at temperature 37ºC, incubation period 48hr, pH7. The Gamma radiation exposure dose 1.5kGy gave the maximum SeNPs produced (10.01 μmole/ml). A pink color appear in the fermented milk revealing the formation of SeNPs-enriched milk. SeNPs inhibit the biofilm formation of Pseudomonas aeruginosa with a percentage reduction of 99.7%. SeNPs increase the antibacterial activity of fucidic acid by 13.6% and 28.5% against Escherichia coli and Staphylococcus aureus respectively. But with Gentamycin sulphate, no change in the antibacterial activity. Conclusion: SeNPs can be synthesized aerobically by the probiotic B. laterosporus bacterial strain. SeNPs can be incorporated in nutraceuticals and functional foods like milk also can be used to inhibit the bacterial biofilm formation and can be added to some antibacterial creams to enhance their antimicrobial activity.

Synthesis of Silver Nanoparticles and Incorporation with Certain Antibiotic Using Gamma Irradiation.

Aims: The study was explaining that silver nanoparticles (AgNPs) were synthesized biologically by Bacillus megaterium culture supernatant (as reducing and stabilizing agents) by the optimization of medium components for nitrate reductase production to enhance the synthesis of AgNPs. And use of gamma irradiation for the synthesis and incorporation of AgNPs with selected antibiotics at distinct dose. Place and Duration of Study: The study was carried out in 2012 in the Department of Drug Radiation Research, Egyptian Atomic Energy Authority. Methodology: The optimized conditions for AgNPs formation by B. megaterium culture supernatant were as follows; media containing: (%) yeast extract: 0.15, peptone: 0.25, KNO3:0.1 temp: 30ºC and incubation period 24 h with maximum nitrate reductase activity of (680.89U/ml). Physical synthesis of AgNPs and incorporation with antibiotics such as (Sodium Cefotaxime, Gentamycin sulphate and Amoxicillin) by γ-rays doses such as (0.5, 1, 1.5, 2, 2.5 and 3 kGy) were studded. AgNPs were characterized by (UV-Vis.), (DLS), (FT-IR) and (TEM) analysis. Combined and individual antibacterial activities of Amoxicillin and AgNPs were investigated against different pathogenic bacterial species by measuring the (ZOI) and by determining the (MIC). Results: This method shows that Aqueous Ag+ ions were reduced to AgNPs when added to the cell-free supernatant of B. megaterium this is indicated by the color change from whitish yellow to brown and the control showed no color change. In physical method Amoxicillin was incorporated with AgNPs perfectly at 2.5kGy. The decreasing order of the average antibacterial activity against bacterial group was observed to be AgNPs > Amoxicillin > Amoxicillin + AgNPs. Conclusion: The radiation-induced AgNPs synthesis is a simple, clean which involves radiolysis of aqueous solution that provides an efficient method to reduce metal ions. B. megaterium was found to be an effective biological tool for the extracellular biosynthesis of AgNPs. The bactericidal activity have proved that AgNPs in combination with amoxicillin kill bacteria at such low concentrations (units of ppm), which do not reveal acute toxic effects on human cell, in addition to overcoming resistance, and lowering cost when compared to conventional antibiotics.

Ethanol production by Kluyveromyces lactis immobilized cells in copolymer carriers produced by radiation polymerization.

The conditions for batch and continuous production of ethanol, using immobilized growing yeast cells of Kluyveromyces lactis, have been optimized. Yeast cells have been immobilized in hydrogel copolymer carriers composed of polyvinyl alcohol (PVA) with various hydrophilic monomers, using radiation copolymerization technique. Yeast cells were immobilized through adhesion and multiplication of yeast cells themselves. The ethanol production of immobilized growing yeast cells with these hydrogel carriers was related to the monomer composition of the copolymers and the optimum monomer composition was hydroxyethyl methacrylate (HEMA). In this case by using batch fermentation, the superior ethanol production was 32.9 g L(-1) which was about 4 times higher than that of cells in free system. The relation between the activity of immobilized yeast cells and the water content of the copolymer carriers was also discussed. Immobilized growing yeast cells in PVA: HEMA (7%: 10%, w/w) hydrogel copolymer carrier, were used in a packed-bed column reactor for the continuous production of ethanol from lactose at different levels of concentrations (50, 100 and 150) g L(-1). For all lactose feed concentrations, an increase in dilution rates from 0.1 h(-1) to 0.3 h(-1) lowered ethanol concentration in fermented broth, but the volumetric ethanol productivity and volumetric lactose uptake rate were improved. The fermentation efficiency was lowered with the increase in dilution rate and also at higher lactose concentration in feed medium and a maximum of 70.2% was obtained at the lowest lactose concentration 50 g L(-1).

Phenylalanine ammonia lyase production by gamma irradiated and analog-resistant mutants of Rhodotorula glutinis.

Mutants resistant to phenylalanine analogs (L-tyrosine, p-fluoro-D, L-phenylalanine (PFP) and trans-cinnamic acid) were isolated from a wild type strain of Rhodotorula glutinis A-97 by mutagenic treatment with gamma radiation and screened for phenylalanine ammonia lyase (PAL) production. One such mutant, gammaT11 (resistant to L-tyrosine), exhibited four times the PAL activity of the parent wild strain A-97. Mutant isolate gammaTFP5.6 which was selected as L-tyrosine and PFP resistant isolate, produced inducible PAL activity at levels 5.94-fold higher than the wild-type A-97 and 2.66-fold higher than its parent mutant isolate gammaT5 which was resistant to L-tyrosine. The mutant isolate gammaTC5d which was resistant to L-tyrosine and trans-cinnamic acid, exhibited 3.48 and 1.56-fold increase in PAL activity compared to the parent wild strain A-97 and its parent mutant isolate gammaT5, respectively. Different media have been examined for the induction of PAL.

Optimization of process parameters for the continuous ethanol production by Kluyveromyces lactis immobilized cells in hydrogel copolymer carrier.

In the present study the optimized parameters for highest ethanol productivity by Kluyveromyces lactis immobilized cells bioreactor were obtained using the method of Lagrange multipliers. Immobilized growing yeast cells in PVA: HEMA (7%: 10%, w/w) hydrogel copolymer carrier produced by radiation polymerization were used in a packed-bed column reactor for the continuous production of ethanol from lactose at different levels of concentrations (50, 100 and 150) gL(-1). The results indicate that volumetric ethanol productivity is influenced by substrate concentration and dilution rate. The highest value 7.17 gL(-1) h(-1) is obtained at higher lactose concentration (150 gL(-1)) in feed medium and 0.3 h(-1) dilution rate. The same results have been obtained through the application of "LINGO" software for mathematical optimization.