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Among 60 isolates of Streptomyces tested; only 40 isolates were capable to utilize l-methionine as the only source of nitrogen in medium. In addition, 24 of these isolates could grow in medium amended with l-methionine as a source of nitrogen and carbon. Qualitative rapid plate assay test shows the ability of 18 of these isolates to grow with a pink color surrounding their colonial growth, while 6 of these isolates could grow and utilize l-methionine without any pink color around their colonial growth. Quantitative assay test shows the rate of l-methioninase production by all isolates tested. Permeabilization treatment including chemical and physical methods proved that l-methioninase was found to be extracellularly produced. The results also indicate that l-methioninase production was not correlated with growth rate or l-methionine consumption in medium. On the other hand, quantitative assay test shows that these six isolates were l-methioninase negative and failed to produce any amount of l-methioninase. In addition, results also show that isolates No. 4 and No. 60 were the most suitable for l-methioninase production, these two isolates were characterized and identified as Streptomyces sp. DMMMH 4 and Streptomyces sp. MDMMH 60 using 16S rRNA with accession No. in gene bank. Furthermore, optimal conditions for enzyme activity produced by the two isolates were established in relation to temperature, pH, reaction time and type of buffer used and its molarities.

Background: Biomass produced as a byproduct from the β-mannanase production process by Aspergillus tamarii NRC 3was evaluated as a biosorbent for the removal and recovery of some heavy metal ions.Results: Under optimal conditions, the isolated strain recorded the highest β-mannanase activity (31.88 Uml −1 ). Thus, the biomass produced from mannanase production process as a byproduct was evaluated as a biosorbent for the removal and recovery of some heavy metal ions from aqueous solutions and an industrial wastewater. The fungal biomass was found to be efficient for the removal of Cu +2 and some heavy metal ions. The biosorption process of copper(II) by Aspergillus tamarii NRC 3 biomass was affected by changing of time, temperature, pH, metal ions concentration, the presence of some heavy metals, and biomass concentration. The rate of Cu +2 uptake from Cu +2 solution proceeded rapidly, and it appeared to be virtually complete during the initial 5 min (92%); the maximum uptake of Cu +2 appeared at 30°C, pH 5, and biomass concentration 5 g w/w. On the other hand, the fungal biomass was to remove considerable proportion of Pb 2+ , Co +2 , Ni 2+ , Fe +3 , and Cr 3+ in addition to Cu 2+ . The uptake of Cu +2 by pretreated biomass was studied. Recovery of the sorbed metal ions by desorbing agents and the potential reuse of the regenerated biomass in metal ions uptake (reloading) were evaluated. Conclusions: Aspergillus tamarii NRC 3 biomass seems to be quite feasible in the removal of heavy metal ions especially Cu +2 from aqueous solutions.

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Synthesis and characterization of Ag/PVA nanocomposite and comparison of its antibacterial activity with bacteriocin (nisin) for some pathogenic bacteria was carried out. Applications of the bacteriocin include dental care products, pharmaceutical products such as stomach ulcers, colon infection treatment and potential birth control. Ag/PVA nanocomposite was prepared by in situ reduction method, in which silver nitrate, gamma irradiation and poly(vinyl alcohol) (PVA) act as precursor, reductant and stabilizer, respectively. The synthesized Ag nanoparticles (Ag-Nps) have potential antibacterial activity toward both Gram-positive and Gram-negative bacteria. Further studies by X-ray diffraction (XRD) and transmission electron microscopy (TEM) have demonstrated the structure and the distribution of Ag nanoparticles caped within PVA polymer chain.