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In the screening of marine mangrove derived fungi for lovastatin productivity, endophytic Aspergillus luchuensis MERV10 exhibited the highest lovastatin productivity (9.5 mg/gds) in solid state fermentation (SSF) using rice bran. Aspergillus luchuensis MERV10 was used as the parental strain in which to induce genetic variabilities after application of different mixtures as well as doses of mutagens followed by three successive rounds of genome shuffling. Four potent mutants, UN6, UN28, NE11, and NE23, with lovastatin productivity equal to 2.0-, 2.11-, 1.95-, and 2.11-fold higher than the parental strain, respectively, were applied for three rounds of genome shuffling as the initial mutants. Four hereditarily stable recombinants (F3/3, F3/7, F3/9, and F3/13) were obtained with lovastatin productivity equal to 50.8, 57.0, 49.7, and 51.0 mg/gds, respectively. Recombinant strain F3/7 yielded 57.0 mg/gds of lovastatin, which is 6-fold and 2.85-fold higher, respectively, than the initial parental strain and the highest mutants UN28 and NE23. It was therefore selected for the optimization of lovastatin production through improvement of SSF parameters. Lovastatin productivity was increased 32-fold through strain improvement methods, including mutations and three successive rounds of genome shuffling followed by optimizing SSF factors.

Objectives: The current study revealed that the used stabilizers greatly affect the morphology as well as the aspect ratio of the obtained gold nanoparticles.Background: Control of the morphology and dimensions of gold nanoparticles during the preparation is an important task for targeting certain applications in demand. Material and methods: Gold nanoparticles were prepared by the reduction of tetrachloroauric(III) acid in the presence of different stabilizers: polyethyleneimine (PEI), polyvinylpyrrolidone (PVP), and chitosan. Results: In the case of using polyethyleneimine, the produced nanoparticles showed a homogenous spherical structure. Meanwhile, in the case of using polyvinylpyrrolidone and chitosan, the produced nanoparticles experience non-homogenous morphology with great diversity. Transmission electron microscopy (TEM) and UVvisible spectrophotometry (UV-vis) techniques were employed to study the criteria of the obtained gold nanoparticles.Conclusions: It was obviously concluded that the type and concentration of the reducing agents that were added during gold preparation and acted as stabilizer templates affect to a great extent the morphology and particle shape. Also, stabilizers affect the homogeneity of the produced gold nanoparticles. In the case of using polyethyleneimine, the produced nanoparticles showed a homogenous spherical structure. Meanwhile, in the case of polyvinylpyrrolidone and chitosan, the produced nanoparticles experience non-homogenous morphology with great diversity.

Multidrug -resistant (MDR) bacteria are considered life-threatening and need fast identification and antibiotic sensitivity testing to overcome this problem. In the current article, we highlighting the potential of developing silver Nanoparticles (AgNPs) using Cinnamomum zylinicum bark extracts as a promising approach. UV, SEM, TEM and FT-IR analysis were carried out to characterize the biosynthesized AgNPs. UV-visible spectroscopy showed the presence of characterized peek at (420 nm), TEM showed spherical shaped and monodispersed nanoparticles of size range 10 to 78.9 nm and FT-IR spectrum confirmed the presence of various functional groups in the biomolecules which serve as a capping agent for the nanoparticles. Biosynthesized (AgNPs) have been evaluated as an antibacterial against MDR gram-negative bacteria Acinetobacter baumanni, Klebsiella pneumoniae, and Pseudomonas aeruginosa strains and gram-positive bacteria Staphylococcus aureus. The results showed that obtained silver Nanoparticles are efficient in inhibiting both gram-positive and gram-negative bacteria when compared with antibiotic giving a zone of inhibition of 25 mm against S. aureus, 24 mm against K. pneumonia, and P. aeruginosa and 22 mm against A. baumanni respectively. Furthermore, the effectiveness of AgNPs against these test strains was assessed with multiple broad spectrum antibiotics. The results demonstrated that the incorporation of antibiotics with AgNPs has amazing antibacterial effects. The highest extent was observed with gentamycin against S. aureas, K. pneumonia, P. aeruginosa and A. baumanni, respectively. The minimum inhibitory concentrations (MICs) of AgNPs were also determined using microdilution assay. This study gives encouragement that AgNPs can be used to improve the effectiveness of the current antibiotics against MDR bacteria.

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