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This study highlights the optimization of extracellular biosynthesis and antimicrobial efficiency of silver nanoparticles (AgNPs) using the crude metabolite of Escherichia coli D8 (MF06257) strain. The bacterial strain had been isolated from a sewage water stream located in Damietta City, Egypt. The optimum conditions for AgNPs production were at temperature 35°C, pH 7 and 1.5mM silver nitrate. The AgNPs biosynthesis was detected in culture filtrate within 1-2 minutes at room temperature (25±2°C) and sunlight. The characterization of AgNPs was studied by UV-Vis spectroscopy (maximum absorbance at 429 nm), X-ray diffraction (XRD) pattern (crystal planes were 110, 111, 200, 211, 220, and 311), transmission electron microscopy (TEM) (AgNPs were spherical in shape ranging from 6 to 17 nm), Fourier transform-infrared (FTIR) spectroscopy (the bands of symmetric and asymmetric amines were assigned at 3421.1 and 2962.13 cm-1, the stretching vibration band of aromatic and aliphatic (C-N) exist at 1392.35 and 1122.37 cm-1 bands), Zeta potential analyser (AgNPs had a negative charge value; -33.6 mV) and size distribution by volume (the presence of capping agent enveloping the AgNPs with a mean size of 136.0-294.3 nm). Nitrate reductase (NR) was assayed as an important partner in the optimized production (the rate of NR reached to 2.18 U/ml). The study demonstrated that AgNPs are potent inhibitors of Staphylococcus aureus, E. coli, Pseudomonas aeruginosa, Alternaria alternata, Fusarium oxysporum and Aspergillus flavus. The antimicrobial activity of AgNPs was studied by TEM. TEM micrographs showed an inhibition of S. aureus cell multiplication. In case of F. oxysporum, a reduction in the size of treated cells, formation of a mucilage matrix connecting the hyphal cells together, the appearance of a big vacuole, lipid droplets an a severe leakage of cytoplasmic contents were detected. AgNPs exhibited MIC values of 6.25μg/ml and 50 μg/ml against S. aureus and Candida albicans, respectively. In addition, AgNPs showed synergy effects by their combination with fluconazole that increased fold areas especially against A. niger, A. flavus and F. oxysporum.

Background and objective Raising growing rabbits is an ideal solution to confront animal protein deficiency, especially in developing countries. The presence of lignin in wheat straw causes limitation of the digestion overall process. The biological delignification is a practical and promising alternative due to improving the digestibility of wheat straw. This study aimed to enhance wheat straw digestibility and enriching it with protein and use it as a growing rabbit feedstuff. Materials and methods Enzymes production of white-rot fungi was assayed in myco-straw and the mean value was recorded. Wheat straw has been treated with the three most effective fungal species with Biological Treated Wheat Straw (BTWS). After that, the myco-straw was grounded and included in diet to evaluate the growth performance, digestibility and blood parameters of a growing V-line rabbit. Results The best three species for enzyme productions were P. sajor-caju, P. columbinus and P. floridanus. The optimum incubation period was 16 days. The fungal treatments showed significant enzymes activity of laccase, Mn-peroxidase, cellulase and xylanase. Body weight, body weight gain and feed conversion ratio of growing V-line rabbits had improved than those of the control. But, nutrients digestibility of the diet containing BTWS and Carcass traits of growing V-line rabbits were non-significant compared with the control one. In comparison with control, the lipid profile had no differences but the total protein was improved. Conclusion White-rot fungal conversion of wheat straw is maybe one potential alternative providing a more practical, environmental-friendly and nutritionally enhancing as rabbits feedstuff. Rabbits fed BTWS-diets had significantly improved growth performance.

The field experiments were carried out in two successive summer seasons of 2014 and 2015 at the experimental farmof the Faculty of Agriculture, Menoufia University, in El-Raheb, Egypt to evaluate yellow inbreed lines of maize throughline x tester analysis.Top crosses were made each of the twenty-five S4 lines and the two testers by hand to give a total of 50 top crosses in2014season. In the second season (2015) two adjacent experiments were conducted under two plant densities. The firstexperimental represented a normal plant density (ND) of 24000 plant/fad., (hills spaced 25 cm apart and one plant/ hill).The second experimental represented plant density (HD) of 30000 plants/fad. (hills spaced 20 cm a part and one planthill). In each experiment the 50 top crosses as well as the two checks hybrids Giza 168 and Giza 176 were grown in aRandomized Complete Block Design with three replications. Performance of inbred lines varied with plant densities.Parental lines L3, L4, L5, L14 and L23 were the best in mean performance and general combining ability effects underthis study. Results indicated that σ² SCA was more important than σ² GCA for all studied traits, plant height at thecombined analysis. Non-additive gene action was more affected by the interaction with environments than the additiveeffects. The top crosses L12 x T2 and L17 x T2 showed desirable significant SCA effects for shortness and the low earplacement under low plant density. Thirteen top crosses showed significant positive SCA effects for grain yield (ard/fad)under HD, LD and combined analysis. Also, the top crosses L1 x T2 and L11 x T2 were significant under high plantdensity. The top crosses (L3 x T1 and L14 x T2) and (L3 x T2) showed significant number of ears per plot and 100-kernelweight relative to two check varieties for the top cross L3 x T1 gave the higher value of heterosis relative to the twochecks for ear weight and grain yield.

L-asparaginase is used as an antileukemic drug and as a food additive to reduce the risk of acrylamide formation. New L-asparaginases are required to reduce costs and avoid clinical side effects. Citrobacter freundii EGY-NE1represents a potential source of new L-asparaginase. We purified extracellular L-asparaginase from Citrobacter freundii EGY-NE1 (through ammonium sulfate precipitation, dialysis, Sephadex-G50 and DEAE-cellulose columns) to 5.83 fold and 25.76 % recovery. The purified L-asparaginase was a low molecular weight enzyme of 19 kDa. It was optimally active at 37 ˚C, pH 8 and 40 mM asparagine. The Km and Vmax of the enzyme were 0.0179 M and 2.66 U/ml, respectively. Ca2+, Mg2+, K+ and Ba+ 2 activated the enzyme, while Na+, Zn+ 2, EDTA, azide, tartrate and HgCl2 inhibited it. The crude and purified enzymes were immobilized by encapsulation in Ca-alginate; this improved their stability and reusability. The entrapped L-asparaginases on Ca-alginate were examined by scanning electron microscope; their protein diameters ranged from 42.17 to 47.37 nm and from 46.78 to 71.97 nm for the immobilized crude and purified enzymes, respectively. Both the immobilized enzymes kept their maximal activity for 10 minutes at 40 ˚C. After the 5th cycle of repeated use, the immobilized purified and crude enzymes kept 91% and 89 % of their activities, respectively.

L-asparaginase produced by various microorganisms which it used for the treatment of leukemia and starchy food industry. Screening of L-asparaginase producing bacteria from soil samples from Damietta different locations was done. The primary screening by qualitative methods using rapid plate assay determined that out of 25 isolates, 20 strains were producing L-asparaginase. The greatest pink color zones were observed for four bacterial isolates(A6, A11, C11 and C19) after 48 hrs. These four isolates that preliminary screened were grown in liquid media for static and submerged fermentation and then used for secondary screening by Nesslerization method. The best four isolates producing L-asparaginase were identified based on morphological, cultural and biochemical tests, as A6, C11 and C19 were identified as Bacillus species and A11 was identified as Staphylococcus species.

Thirty seven actinomycetes isolates were isolated from Damietta soil using starch nitrate agar media. These isolates were screened for APPL (acid precipitable polymeric lignin) by using minimal salts-yeast extract medium with rice and wheat straws. Three actinomycetes isolates showed high APPL production. These isolates also showed production of cellulase and xylanase with different levels. These isolates were identified by using morphological, physiological and chemotaxonomy criteria and were identified as Streptomyces canus, Streptomyces libani and Streptomyces cyaneus.

The fungus–substrate interaction on the antioxidant activity of a solid state fermentation system (SSFS) was investigated employing two basidiomycete fungi: Pleurotus columbinus and P. floridanus and two ascomycetes: Aspergillus fumigatus and Paecilomyces variotii on powdered peels of banana, pomegranate and orange, empty pea pods and rice straw. The oven-dried substrates were moistened at 90% water holding capacity, inoculated with the test fungi and incubated at 25 °C for appropriate time. Culture extracts were tested for the enzymatic and non-enzymatic antioxidant activity. The effect of substrate on the antioxidant activity of the SSFS was stronger than that of the fungal species. Peroxidase (POX) activity was higher in the basidiomycetes than ascomycetes and achieved its maximum in P. floridanus versus complete absence in A. fumigatus. By contrast, catalase (CAT) activity was higher in the ascomycetes, particularly P. variotii on banana peel, than in the basidiomycetes. Phenolics and flavonoids were highest in pomegranate peels but lowest in banana peels and rice straw, and they were subjected to severe consumption by the basidiomycetes versus mild production by the ascomycetes. The reducing power (RP) and DPPH scavenging activity were higher in the peels of pomegranate, orange and banana relative to rice straw and empty pea pods, and the fungal effect was limited and independent of the fungal taxonomic group. Orange peel is the appropriate substrate for production of fungal CAT and POX, which activities were mutually exclusive; but pomegranate peel is more suitable for production of phenolics and flavonoids.

The enzymatic and non-enzymatic antioxidant activities of a solid-state fermentation system (SSFS) employing six basidiomycete and four ascomycete fungi on orange peel have been evaluated. Class comparisons revealed highly significant effect of fungal group on the antioxidant activity. Peroxidase activity appeared only in the basidiomycete fungi (particularly Pleurotus columbinus, Ganoderma resinaceum, and Pleurotus floridanus) whereas catalase activity appeared in the two fungal groups in favor of the ascomycetes (particularly Paecilomyces variotii and Aspergillus fumigatus). Maximal peroxidase and minimal catalase activities were found at moderate phenolic content, with extreme phenolic levels leading to low peroxidase activity but high catalase activity. Production of the non-enzymatic antioxidants (phenolics, flavonoids, reducing power, and DPPH scavenging) was in favor of the ascomycetes, which showed great native ability to synthesize flavonoids and also to release flavonoids from orange peel. The basidiomycete fungi, which have limited native ability to produce phenolics, had high ability to consume orange peel phenolics. By contrast, the ascomycete fungi exhibited great native ability for production of phenolics and low ability to consume exogenous phenolics.

This study was concerned with the isolation of bacterial strains from different water sources. Among these strains; Enterobacter sp. exhibited extracellularly biosynthesized silver nanoparticles with good monodispersity. Enterobacter sp. has produced extremely stable nanoparticles within 72 hrs at 35°C in dark conditions. These nanoparticles are characterized by UV–vis spectrophotometer, transmission electron microscopy, Zeta potential analyzer, and size distribution by volume. Enterobacter sp. synthesized 9.45-17.15 nm sized spherical shaped silver nanoparticles. The presence and binding of stabilized proteins with nanoparticles were confirmed by the zeta size distribution by volume. Our study demonstrates that silver nanoparticles are potent inhibitors of the plant pathogenic fungus, Fusarium oxysporum f. sp. lycopersici.

Summary Alkali pretreatment of pods of bean, rice plant straw, wheat bran, sugar-cane bagasse and sawdust enhanced their degradation by Aspergillus sydowii ( Bainier & Sartory ) Thom & Church . The fungus could produce 0.153 g dry mycelium when grown on 100 ml of 10% NaOH pretreated sawdust-containing medium. Alkali hydrolysates were assimilated better than the cellulosic pulps of different wastes. Maximal growth amounting to 0.239 g/100 ml dry biomass was produced on hydrolysate of 10% NaOH pretreated sawdust for 30 minutes. Highest accumulation of different cellulases and pectinase was occurred on cellulosic pulps-containing media. Good xylanolytic activity has been achieved on both cellulosic pulps and hydrolysates media. Cellulases, xylanase and pectinase of A. sydowii were proved to be an inducible enzymes.

Summary Aspergillus terreus THOM produced appreciable yield of xylanase on medium containing acid pretreated rice straw as sole carbon source. The enzyme was purified approximately 25-fold by ammonium sulfate precipitation, gel filtration through Sephadex G-50 and ion-exchange chromatography on DEAE-cellulose with a yield of about 23% and specific activity of 15.38 units/mg protein. Optimum activity against xylan was at 45 °C and pH 4.5. Relative stability of the enzyme was recorded at pH range of 4–5.5. Heating the enzyme preparation at 60 °C for one hour resulted in a 82.61 % loss of activity. After exposing to 90 °C for 10 minutes xylanase retained 4.28% of its original activity. The purified enzyme lost 25 % of the original activity after keeping at 4 °C for 9 months in 0.05 M acetate buffer (pH 4.5). The Km value of the enzyme was found to be 0.83 mM. Zn2+ was the most enhancing agent for xylanase activity. Cu2+ followed by Co2+ and K+ were the more deterrent cations. Xylanolytic activity of A. terreus was strongly inhibited by HgCl2, 2,4-dinitrophenol (DNP), phloridzin and ethylene diamino tetra acetic acid (EDTA).

Aspergillus carbonarius was recorded as a good producer of microbial cell wall lytic enzymes. The enzyme preparation effectively lysed both living and heat-treated cells of some bacteria and yeasts. Polymers of microbial cell wall constitution had been also hydrolysed. Production of the highest content of lytic enzymes was induced by killed cells of Escherichia coli. The crude preparation revealed its maximal bacteriolytic activity at pH 7.2 and 35 degrees C. Endo-1,3-beta--glucanase, mannanase and protease were the prevailing enzymes in this preparation.

Aspergillus terreus THOM produced appreciable yield of xylanase on medium containing acid pretreated rice straw as sole carbon source. The enzyme was purified approximately 25-fold by ammonium sulfate precipitation, gel filtration through Sephadex G-50 and ion-exchange chromatography on DEAE-cellulose with a yield of about 23% and specific activity of 15.38 units/mg protein. Optimum activity against xylan was at 45 degrees C and pH 4.5. Relative stability of the enzyme was recorded at pH range of 4-5.5. Heating the enzyme preparation at 60 degrees C for one hour resulted in a 82.61% loss of activity. After exposing to 90 degrees C for 10 minutes xylanase retained 4.28% of its original activity. The purified enzyme lost 25% of the original activity after keeping at 4 degrees C for 9 months in 0.05 M acetate buffer (pH 4.5). The Km value of the enzyme was found to be 0.83 mM. Zn2+ was the most enhancing agent for xylanase activity. Cu2+ followed by Co2+ and K+ were the more deterrent cations. Xylanolytic activity of A. terreus was strongly inhibited by HgCl2, 2,4-dinitrophenol (DNP), phloridzin and ethylene diamino tetra acetic acid (EDTA).

Acid pretreatment of cellulosic wastes improved their susceptibility to Fusarium acuminatum enzymes. The effectiveness of acid pretreatment was demonstrated with an increase in both fungal growth and enzyme activities. A growth yield of 0.15 g/100 ml was achieved on medium containing 5% acid pretreated pods of bean for 60 minutes. Avicelase (C1), carboxymethylcellulase (Cx) and B-glucosidase (C2) reached their maximal biosynthesis on acid pretreated wheat bran, sugar-cane bagasse and sawdust-containing media, respectively. Xylanase and pectinase attained their highest accumulation on pretreated pods of bean media. A mixture of free sugars has been released by acid pretreatment. O.199 g dry mycelium was obtained when the fungus was grown on 100 ml of medium containing hydrolysate of 10% H2SO4 pretreated pods of bean for 30 min. No cellulase enzymes could be detected on hydrolysate medium at the time that low contents of both xylanase and pectinase were accumulated.

Summary An extracellular phytase from Aspergillus flavipes (Bainier & Sartory) Thom & Church was purified about 173-fold from a culture filtrate by precipitation with ammonium sulfate, gel filtration through Sephadex G-75, and column chromatography on DEAE-cellulose. Maximum enzyme activity was observed at p H 5.6 and 37.5 °C when calcium phytate was used as substrate. The enzyme was stable between p H 5.6 and 0.8. Heating the enzyme solution at 45°C for 60 min resulted in a 84.4% loss of activity. However, the enzyme was stable for 8 weeks when kept at 4°C in 0.05 M Tris-HCl buffer ( p K 8.2). The K m value was calculated to be 0.63 mM. The enzyme is activated by Zn 2+ , Ca 2+ , Mn 2+ , and K + and strongly inhibited by arsenite, arsenate, and fluoride. No carbohydrate and phosphorus were detected in the enzyme preparation, suggesting that this enzyme is a simple protein.

Summary Intracellular phytase from Macrophomina phaseolina (Tassi) Goid. was purified 113.28-fold from dialyzed cell-free extract by precipitation with acetone, gel filtration and ion exchange chromatography on a column of DEAE-cellulose. The enzyme showed optimum activity at pH 5.6 and 35°C. Intracellular enzyme preparation is sensitive to heating and lost about 95% of its activity after heating at 45°C for 60min. Moreover its activity is rapidly lost on keeping at 4°C. The Km value was calculated to be 0.91 mM. This enzyme is activated by Zn2+, Ca2+ and K+ and strongly inhibited by arsenate and arsenite.