Search

Streptomyces atrovirens was isolated from soil samples in Egypt and showed broad spectrum antimicrobial activity. It was identified as Streptomyces atrovirens (strain H33) based upon16S rRNA gene sequencing. It was deposited in the GenBank database under accession number of KJ435269. Streptomyces atrovirens (strain H33)was cultivated by submerged fermentation bioreactor to produce the antimicrobialmetabolites. Purification and identification of antimicrobial compound was carried out. The antimicrobial compound exhibited low cytotoxic effect on human epithelial HL cells. Key words: 16S rRNA, bioreactor; cytotoxicity, HPLC MS/MS, Streptomyces atrovirens H33. REFERENCES Bauer, A.W., Kirby, W.M. M., Sherris, J.C., and Turck, M. (1966). Antibiotic susceptibility testing by a standardized single disk method. Am. J. Clin. Pathol.45, 493-496. Berdy, J. (2005). Bioactive microbial metabolites. J. Antibiot. (Tokyo), 58, 1-26. Cho, J. Y. and Kim, M. S. (2012) Antibacterial benzaldehydesproduced by seaweed-derived Streptomyces atrovirens PK288-21. Fish. Sci., 78, 1065-1073. Elibol, M., Ulgen, K., Kamarulzaman, K., andMavituna, F. (1995). Effect of inoculum type on actinorhodin production by Streptomyces coelicolor. Biotechnol. Lett.,17, 579-582. Felsenstien, J. (1985). Confidence limits on phylogenies: an approach usingthe bootstrap.Evolution, 39, 783-791. Garrod, L. P. and Waterworth, P. M. (1971). A study of antibiotic sensitivity testing with proposals for simple uniform methods. J. Clin. Pathol.,24, 779-789. Hobbs, G., Frazer, C.M., Gardner, D.J.C., Cullum, J.A., and Oliver, S.G. (1989). Dispersed growth of Streptomyces in liquid culture. Appl. Microbiol. Biotechnol.,31, 272-277. Hosny, A.M. S., Sheir, D. H., Abdelallah,N. A., Amin, D. H. M., El-Diwany,A. I., Abdelwahed, N.A. M., El-Beih,A. A., Fallarero,A., and Vuorela,P. M. (2015). Isolation ofStreptomyces sp. producing antifungal agent. Vol. 4 (2) April-June, Curr.Sci. Int. (In press). Karlsson, D., Fallarero. A., Brunhofer, G., Mayer, C., Prakash, O.et al. (2012). The exploration of thienothiazines as selectivebutyrylcholinesterase inhibitors. European Journal of Pharmaceutical Sciences, 47,190-205. Kim,K-J., Kim,M-A.,and Jung,J-H. (2008). Antitumor and antioxidant activity of protocatechualdehyde produced from Streptomyces lincolnensisM-20. Arch. Pharm. Res., 31,(12), 1572-1577. Lane, D., Pace, B., Olsen, G., Stahl, D., Sogin , M. et al. (1985). Rapid determination of 16S ribosomal RNA sequence for phylogenetic analyses. Proc. Natl. Acad. Sci.U. S. A., 82, 6955 –6959. Locatelli, L., Tarnawski, S., Hamelin, J., Rossi,P., Aragno, M. et al. (2002). Specific PCR amplification for the genus Pseudomonas targeting the 3 half of 16S rDNA and the whole 16S- 23S rDNA spacer. Syst. Appl. Microbiol.,25, 220-227. Mann, J. (2001). Natural products as immunosuppressive agents. Natural Product Reports, 18, 417-430. Olano,C., Moss, S. J., Braña, A. F., SheridanR. M., MathV. et al. (2004). Biosynthesis of the angiogenesis inhibitor borrelidin by Streptomyces parvulus Tü4055: insights into nitrile formation. Mol. Microbiol.,52 (6), 1745–1756. Oldfield, C., Wood, N. T., Gilbert, S. C., Murray, F. D., and Faure, F. R. (1998). Desulphurisation of benzothiophene and dibenzothiophene by actinomycete organisms belonging to the genus Rhodococcus, and related taxa. Antonie Van Leeuwenhoek, 74,119-132. Pranitha, G. Krishna and M.A Singara Charya (2014). Evaluation of antibacterial and anifungal activity of fruiting Body extracts of trametes versicolar. Biolife. 2(4):1181-1184. Raintala, H., Nvalainen, A., Ronka, E., and Suutari, M. (2001). PCR primers targeting the 16S rRNA gene for the specific detection of Streptomyces. Mol. Cell. Probes,15, 337-347. Raja A. and Prabakarana P. (2011). Actinomycetes and drug-An overview. Am. J. of Dru. Dis. and Dev., 1, 75-84. Saito, N. and Nei, M. (1987). The neighbor-joining method: a new method for reconstructing phylogenetic trees. Mol. Biol. Evol., 4, 406-425. Shaaban, K.A., Shepherd, M.D., Ahmed, T.A., Nybo, S.E., Leggas, M. et al. (2012). Pyramidamycins A-D and 3-Hydroxyquinoline-2-carboxamide; Cytotoxic Benzamides from Streptomyces sp. DGC1.J.Antibiot. (Tokyo),65(12): 615-622. Shirling, E.B. and Gottlieb, D. (1966). Methods for characterization of Streptomyces sp. Int. J. Syst. Bacteriol.,16, 313-340. Su, W. W. (2006). Bioreactor engineering for recombinant protein production using plant cell suspension culture. In: Plant Tissue Culture Engineering, S. Dutta Gupta and Y. Ibaraki (Eds), Springer, Printed in the Netherlands, pp. 135-159. Tamura, K., Stecher, G., Peterson, D., Filipski, A., and Kumar, S.(2013). MEGA6: Molecularevolutionary genetics analysis version 6.0. Mol. Biol. Evol., 28(10), 2731-2739. Vandamme, E.J. (1983). Peptide antibiotic production through immobilized biocatalyst technology. Enzyme Microb. Technol.,5, 403–416

Pancreatic cancer is the fourth most lethal cancer type worldwide. Due to multiple levan applications including anticancer activities, studies related to levansucrase production are of interest. To our knowledge, levan effect on pancreatic cancer cells has not been tested previously. In this work, among eighteen bacterial honey isolates, Bacillus subtilis MT453867 showed the highest levan yield (33 g/L) and levansucrase production (8.31 U/mL). One-factor-at-a-time technique increased levansucrase activity by 60% when MgSO4 was eliminated. The addition of 60 g/L banana peels enhanced the enzyme activity (192 U/mL). Placket Burman design determined the media composition for maximum levan yield (54.8 g/L) and levansucrase production (505 U/mL). The identification of levan was confirmed by thin-layer chromatography, Fourier-Transform Infrared spectrometric analysis, 13C-nuclear-magnetic resonance, and 1H-nuclear-magnetic resonance. Both crude and dialyzed levan completely inhibited the pancreatic cancer cell line at 100 ppm with no cytotoxicity on the normal retinal cell line. The LD50 of crude levan was 4833 mg/kg body weight. Levan had strong antioxidant activity and significantly reduced the expression of CXCR4 and MCM7 genes in pancreatic cancer cells with significant DNA fragmentation. In conclusion, Bacillus subtilis MT453867 levan is a promising adjunct to pancreatic-anticancer agents with both anti-cancer and chemoprotective effects.

This overall process deals with evaluating the performance of silver nanoparticles, synthesized from sodium caseinate (SC) as green biological active agent, in comparison with widely produced from carboxymethyl cellulose, other carbohydrates (oxidized nanocellulose fibres (OC) and starch (St)). The TGA, FTIR and TEM, as well as its antimicrobial activities toward pathogenic Gram-positive and Gram-negative bacteria in addition to the yeast strain Candida albicans NRRL Y-477 were examined. In addition, with regard to their anti-tumour activity, the evaluation was studied via many cancer cell lines against RPE1 (normal retina cell line). The results revealed that the SC–Ag(I) and CMC–Ag(I) complexes were formed in six- and five-membered chelate rings, respectively, as nanoparticles, while linear chelation structure was formed in case of OC–Ag(I) and St–Ag(I) complexes. The complexation of SC with Ag(I) ions was recommended as promising stable and antimicrobial agent, with lower free Ag(I) ions and particle size than other Ag-complexes. Moreover, it provided anti-tumour activity of most tested cell lines ( in vitro ), with the following sequence HCT116 > PC3 > HePG 2 > MCF-7 > A549 with IC 50 and IC 90 values of 25.8 and 54.73 µg ml −1 , 45.1 and 66.7 µg ml −1 , 64.3 and 110.7 µgml −1 , 71.4 and 114.8 µgml −1 and 80.1 and 127.7 µgml −1 , respectively. The promising effect of SC–Ag complex was also clear from its selective index versus RPE1 (normal retina cell line).

Objective: L-Asparaginase is an important enzyme that converts L-asparagine to L-aspartate and ammonia. Microbial L-asparaginase has important applications as anticancer and food processing agents. Methods: This study reported the isolation, screening of a local yeast isolate from banana peel for L-asparaginase production using submerged fermentation, optimization of the production, purification, and anticancer assay of L-asparaginase. The yeast isolate was identified as Kodamaea ohmeri ANOMY based on the analysis of nuclear large subunit (26S) rDNA partial sequences. It was a promising L-asparaginase producer with a specific activity of 3059±193 U/mg in a non-optimized medium. The classical one-variable-at-a-time method was used to optimize the production medium components, and it was found that the elimination of K2HPO4 from the medium increased L-asparaginase specific activity (3100.90±180 U/mg). Results: Statistical optimization of L-asparaginase production was done using Plackett-Burman and Box-Behnken designs. The production medium for the maximum L-asparaginase specific activity (8500±578U/mg) was as follows (g/L): L-asparagine (7.50), NaNO3 (0.50), MgSO4.7H2O (0.80), KCl (0.80) associated with an incubation period of 5 days, inoculum size of 5.60 %, and pH (7.0). The optimization process increased L-asparaginase production by 2.78-fold compared to the non-optimized medium. L-Asparaginase was purified using ammonium sulphate precipitation followed by gel filtration on a Sephadex G-100 column. Its molecular weight was 66 KDa by SDS-PAGE analysis. Conclusion: The cell morphology technique was used to evaluate the anticancer activity of L-asparaginase against three different cell lines. L-Asparaginase inhibited the growth of HepG-2, MCF-7, and HCT-116 cells at a concentration of 20, 50, and 60 μL, respectively.

In this work, erythromycin production by Saccharopolyspora erythraea NCIMB 12462 was investigated under solid state fermentation (SSF) using beet sugar root (BSR) and agro-industrial materials. Among them oat meal (OM) has given maximum yield. The combination of OM with BSR (3:3 g/flask) proved to be an efficient mixture for erythromycin production as they gave the highest erythromycin level (6531 μg/flask) when compared to BSR and peptone. Supplementation of BSR and OM mixtures with sugarcane bagasse (SCB) as inert support with different inoculum size and additional water enhanced erythromycin production with 3.1-fold higher production than BSR- OM medium. However, increasing SCB content more than 3g/flask always showed an inhibitory effect on erythromycin production. Box-Behnken response surface methodology was applied to further optimize SCB content, inoculum size and moisture level for erythromycin production. Statistical analysis of the results showed that the linear of the selected terms, their interactions and quadric terms of these three variables had significant effects. The moisture level was the key factor influencing erythromycin production, due to its largest F-value (48.01) and the lowest p-value (0.0002) among the three variables. The interactions between SCB content and moisture level had also the most significant effect (F-value = 32.51) on erythromycin production. The optimized medium produced 29884 ug/flask of erythromycin under SSF, which is 1.1% higher than the unoptimized medium.

Isolation and identification of new microbial isolates capable of producing cholesterol oxidase enzyme (CHO) is of great potential in the field of biotechnology of industrial enzymes. Four producing strains of actinomycetes were isolated from Egyptian soils demonstrated high activity in cholesterol degradation compared to the other isolates. Based on different standard morphological, biochemical as well as molecular techniques using 16S rRNA sequencing, these actinomycetes were identified as Streptomyces sp. strain NHIA_CH3 MK680299, Streptomyces sp. strain NHIA_CH5 MK680300 , Streptomyces griseus strain NHIA_CH6 MK680301 and Streptomyces drozdowiczii strain NHIA_CH10 MK680302. In order to optimize the CHO enzyme activity, different fermentation media were tested in submerged cultures at shake flask level. Maximum activity (23.7 U/mL) was observed in culture of Streptomyces sp. strain NHIA_CH5 which was scaled up to the 5L volume of the stirred tank bioreactor. Results of the batch fermentation showed an earlier production of CHO enzyme with 4% increase in activity compared to that obtained from shake flask cultures indicated that Streptomyces sp. strain NHIA_CH5 could be a potential source of CHO enzyme for commercial purpose.

L-asparaginase is a promising enzyme that has a wide range of significant applications including cancer therapy and starchy food industries. The statistical design of Plackett–Burman and face centered central composite design were employed to optimize L-asparaginase production by Streptomyces brollosae NEAE-115. As a result, a medium of the following formula is the optimum for producing L-asparaginase in the culture filtrate of Streptomyces brollosae NEAE-115: Dextrose 2 g, starch 20 g, L-asparagine 10 g, KNO3 1 g, K2HPO4 1 g, MgSO4.7H2O 0.5 g, NaCl 0.1 g, pH 7, fermentation period 7 days, temperature 30 °C, inoculum size 4%, v/v, agitation speed 150 rpm and inoculum age 48 h. The kinetics of cell growth, carbohydrates consumption and L- asparaginase production were studied in 7-L stirred tank bioreactor under different cultivation conditions. A significant increase in both cell growth and carbohydrate consumption was observed as the stirring speed increased from 200 to 600 rpm under uncontrolled pH. The highest L- asparaginase activity of 108.46 U/mL was obtained after 96 h at 400 rpm. On the other hand, the specific enzyme production (Yp/x) under uncontrolled pH reached its maximal value of about 20.3 U/mg cells. Further improvement of enzyme production was attained by controlling pH at 7 using the selected stirring speed of 400 rpm. Enzyme production of 162.11 U/mL obtained from the controlled pH cultures exceeded this value gained from uncontrolled pH (108.46 U/mL) by about 50%.

Optimization of the fermentation conditions for extracellular production of L-asparaginase by Streptomyces brollosae NEAE-115 under solid state fermentation was investigated. The Plackett–Burman experimental design was used to screen 16 independent variables (incubation time, moisture content, inoculum size, temperature, pH, soybean meal + wheat bran, dextrose, fructose, L-asparagine, yeast extract, KNO3, K2HPO4, MgSO4.7H2O, NaCl, FeSO4. 7H2O, CaCl2) and three dummy variables. The most significant independent variables found to affect enzyme production, namely soybean + wheat bran (X6), L-asparagine (X9) and K2HPO4 (X12), were further optimized by the central composite design. We found that L-asparaginase production by S. brollosae NEAE-115 was 47.66, 129.92 and 145.57 units per gram dry substrate (U/gds) after an initial survey using “soybean meal + wheat bran” as a substrate for L-asparaginase production (step 1), statistical optimization by Plackett–Burman design (step 2) and further optimization by the central composite design (step 3), respectively, with a fold of increase of 3.05.

The present study investigates, the synthesis of new derivatives of benzenesulfonamide nucleus hybridized with various substituted pyrazole 4, 8 and thiazole ring 6 using 4-amino-N-butylbenzenesulfonamide 1 as the key starting compound. Furthermore, 3,5-diaminopyrazole derivative 10 was allowed to react with different reagents such as an active methylene compounds, ketone dithioacetal, ethoxymethylene malononitrile and cyanoguanidine for a preparation of new benzenesulfonamide derivatives 11-18 conjugated with different substituted hetero-bicyclic ring systems. In vitm-antimicrobial evaluation was performed for most of the newly synthesized compounds using ciprofloxacin and Fluconazole as antibacterial and antifungal standard drugs, respectively The most promising dual antibacterial and antifungal potency was gained by the sulfamoylphenyl butenoic acid derivative 7, followed by the sulfamoylphenyl-2-chloroacetamide 5 and its heterocyclic pyrazolopyrimidine derivative 16. Further development and structural optimization will be carried out to get new more potent and safer antimicrobials.

The present work involves synthesis of new 3,5-bis-substituted dihydropyridine derivatives 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 starting from dihydropyridine-3,5-dicarboxylate (1) as starting material. Structures of new compounds were established by spectral and elemental analyses. Some of the new compounds were evaluated for anticancer and antimicrobial activity. Screening data of the tested compounds show promising anticancer and antimicrobial activity. The detail synthesis, spectroscopic data, and pharmacological activities are reported.

This study aim to isolate, identify and optimize lipase producing strains using frying oil waste. Nine strains were isolated from an Egyptian soil samples. Among the isolates, a potent bacterial candidate ASSCRC-P1 was found to be the most potent lipase producer strain at 60 °C. Genotypic identification of ASSCRC-P1 showed 94% similarity with Bacillus sp. strains. Phylogenetic tree confirmed that ASSCRC-P1 was nearly similar to Bacillus cereus. Therefore, it was given the name Bacillus cereus ASSCRC-P1 and its 16S rRNA nucleotide has been deposited in the GenBank Data Library under the accession number: KJ531440. A sequential optimization strategy, based on statistical experimental designs, was employed to enhance the lipase production by this strain. A 2-level Plackett–Burman design was applied to differentiate between the bioprocess parameters that significantly influence lipase production followed by Box-Behnken design to optimize the amounts of variables which have the highest positive significant effect on lipase production. Overall more than 2.15-fold improvement in lipase production was achieved due to optimization compared to that obtained using the basal medium.

Response surface methodology was used to optimize lincomycin production by Streptomyces lincolnensis NRRL ISP-5355 in submerged fermentation. Screening of fermentation medium components to find their relative effect on lincomycin production was done using Plackett-Burman design. Malt extract, dextrin, soluble starch and (NH4)2SO4 were the most significant nutrient influenced on lincomycin production. Central composite design was applied to determine optimal concentrations of these factors and the effect of their mutual interactions. The interaction between soluble starch and (NH4)2SO4 was found to enhance the production, whereas malt extract and dextrin exhibited an influence independent from the other two factors. Using this statistical optimization method, maximum lincomycin concentration of 1345 μg/ml was obtained which represented a 40.5 % increase in titer than that acquired from the non-optimized medium. This statistically optimized medium was employed for lincomycin production through immobilization of Streptomyces lincolnensis by adsorption on synthetic cotton fibers. Immobilization technique improved the concentration to 1350 μg/ml higher than that produced from free cells cultures and could be maintained for longer than 17 days in a repeated batch system.

The current research was focused on the extracellular biosynthesis of bactericidal silver nanoparticles (AgNPs) using cell-free supernatant of a local isolate previously identified as a novel Streptomyces aegyptia NEAE 102. The biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102 was quite fast and required far less time than previously published strains. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV-Vis spectroscopy, which confirmed the presence of AgNPs. Response surface methodology was chosen to evaluate the effects of four process variables (AgNO3 concentration, incubation period, pH levels, and inoculum size) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. Statistical analysis of the results showed that the linear and quadratic effects of incubation period, initial pH, and inoculum size had a significant effect (p < 0.05) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. The maximum silver nanoparticles biosynthesis (2.5 OD, at 400 nm ) was achieved in runs number 5 and 14 under the conditions of 1 mM AgNO3 (1-1.5% (v/v)), incubation period (72-96 h), initial pH (9-10), and inoculum size (2-4% (v/v)). An overall 4-fold increase in AgNPs biosynthesis was obtained as compared with that of unoptimized conditions. The biosynthesized silver nanoparticles were characterized using UV-VIS spectrophotometer and Fourier transform infrared spectroscopy analysis, in addition to antimicrobial properties. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic gram-positive (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) and yeast (Candida albicans).

Optimization of alkaline protease production by Streptomyces ambofaciens NRRL 2420 in free and immobilized form was investigated using submerged fermentation technique. The optimum conditions for maximum alkaline protease production 342 unit mL -1 were 30°C at pH 8.5 and incubation time 96 h in fr ee cell cultures using starch 20 g L -1 as carbon source and yeast extract 5 g L -1 as nitrogen source. The incubation time for the best yield of 344 unit mL -1 was reduced to 72 h under the optimized fermentati on conditions by immobilized cells adsorbed on synthetic cotton fibe rs. Data obtained during 5 reusable cycles showed h igher levels of enzyme in shorter time duration. Immobili zation of Streptomyces ambofaciens NRRL 2420 on synthetic cotton fiber permit repeated reuse of the cells under the optimized fermentation conditions.

Some new S-alkyl derivatives of indeno[1′,2′:4,5]thieno[2,3-d]pyrimidine 2–8 were prepared starting with pyrimidine-2(1H)-thione derivative (1). Also, treatment of compound 1 with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide or 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose afforded nucleosides 9 and 12, respectively. Furthermore, deprotection of the latter blocked nucleosides was achieved in methanolic ammonia to afford the desired free S-nucleoside derivatives 10 and 13, respectively. Some prepared products were screened for antimicrobial activity, and some of them showed promising activity.

An ecological and viable approach for the in situ forming silver nanoparticles (AgNPs) on cotton fabrics has been used. Silver nanocoated fabric of brownish yellow color (AgNPs, plasmon color) was characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). SEM images revealed that the surface of the modified cotton was rougher than that of normal cotton. In addition, SEM images showed the presence of AgNPs on the surface of the treated fabric. Silver mapping and elemental analysis of the silver nanocoated cotton fabric using EDS confirmed the presence of AgNPs in a homogeneous distribution. Also, FTIR spectra of silver nanocoated sample showed more intense and broad peaks with a slight red shift if compared with those of blank sample indicating the binding of AgNPs with cellulose macromolecules. Different coating levels and the impact of repeated washings have been evaluated against different microbial strains by growth inhibition zone. The results of antimicrobial studies reveal that the presence of a low coating level of nanosilver is enough for producing an excellent and durable antimicrobial cotton fabrics.

Purpose: To enhance clavulanic acid production using UV-mutagenesis on Streptomyces sp. NRC77.Methods: UV-mutagenesis was used to study the effect of Streptomyces sp. NRC77 on CA production. Phenotypic and genotypic identification methods of the promising mutant strain were characterized. Optimization of the fermentation medium and culture conditions were investigatedResults: Out of the screened mutants, 120A3 mutant isolate was selected as promising. The phenotypic properties of 120A3 mutant showed culture characteristics similar to those of Streptomyces species. Phylogenetic analysis of 16S rRNA gene sequence indicate that this strain has similarity (99 %) to Streptomyces sp.T2-7; therefore it was suggested as Streptomyces sp. MU-NRC77 and has Gen Bank accession no. KT953342.Conclusion: Improvement of CA yield by 48 % was obtained from fermentation medium and culture condition optimization. Further optimization by addition of H2O2 and activated charcoal to the production medium increased CA yield to 646.12 and 682.94 mg/L respectively, i.e., 83 % more than that obtained prior to addition.Keywords: Clavulanic acid, Medium optimization, Phenotypic and Genotypic identification, Streptomyces sp. MU-NRC77, UV-Mutagenesis

One hundred and forty one actinomycetes strains were isolated from Egyptian and Saudi Arabia soils and decayed rice straw samples. The isolated actinomycetes strains were screened for their cellulolytic activities on carboxymethyl cellulose (CMC) - containing agar plates. Streptomyces sp. NEAE-D showed the highest carboxymethyl cellulase (CMCase) activity. The optimum conditions for CMCase production were the use of pretreated rice straw as the best carbon source that supported better CMCase production than carboxymethyl cellulose after 5 days incubation at pH 6.5 and at 35°C in the presence of yeast extract as nitrogen source. Crude CMCase activity was characterized. The highest activity was recorded after 50 min incubation, at 50°C, pH 6.0 and 2% substrate concentration, the CMCase was shown to be alkali-tolerant enzyme whose activity was stable over a broad pH range (7 to 10). The enzyme retained 97.31 and 70.99% of its activity at 50 and 60°C respectively after 60 min. High performance liquid chromatography (HPLC) analysis of the hydrolysate of saccharified pretreated rice straw identified the formation of glucose, cellobiose, mannose and xylose as byproducts. Key words : Carboxymethyl cellulase, production, pretreated rice straw, alkali-tolerant, Streptomyces sp. NEAE-D, characterization.

Central composite design was chosen to determine the combined effects of four process variables (AgNO3 concentration, incubation period, pH level and inoculum size) on the extracellular biosynthesis of silver nanoparticles (AgNPs) by Streptomyces viridochromogenes. Statistical analysis of the results showed that incubation period, initial pH level and inoculum size had significant effects (P

A number of substituted phenytoin derivatives in addition to their sugar hydrazones were newly synthesized. Furthermore, the corresponding derived 1,3,4-oxadiazole and their thioglycoside as well as their acyclic analogs were prepared. The antimicrobial activity of the prepared compounds was evaluated against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Aspergillus niger and Candida albicans. The dithiohydrazone as well as oxadiazole thiole derivatives, sugar hydrazones and acyclic nucleoside analogs were the highly active compounds.

Among the tested compounds the nucleoside analogue (III) exhibits the highest antimicrobial activity.

(9-Methyl-5,6-dihydronaphtho[1',2':4,5]thieno[2,3-d]pyrimidin-11-yl)hydrazine (1) was used as a precursor for preparation of some novel 1-(9-methyl-5,6- dihydronaphtho[1',2':4,5]thieno[2,3-d]pyrimidin-11-yl)-1H-pyrazoles 2–7, -1H-isoindole- 1,3(2H)-dione 8, and -pyridazin-3(2H)-one 9. Moreover, the acyclic C-nucleosides 10 and 11 were prepared by treating compound 1 with D-glucose. The in vitro antimicrobial activity of the tested compounds was evaluated by measuring the zone diameters and some of the prepared products showed potent antimicrobial activity in compared with those of well known drugs (standard). In general, the non-acetylated sugar hydrazone derivative 10 showed the highest antibacterial and antifungal potency among the tested compounds and standard with IZ = 22, 21 and 22 mm and MIC = 62.5 and 31.25 μg/ml, respectively.

Marine endophytic fungi isolated from Red Sea organisms were screened for the production of dextranase enzyme. The most potent isolate was from the Red Sea sponge Callyspongia spp. and was selected for identification. The18S rRNA amplification for phylogenetic study revealed that the isolate was highly related to Aspergillus flocculosus strain NRRL 5224 by 99 %. Medium composition and culture conditions for dextranase production were optimized by response surface methodology. A significant influence of dextran, yeast extract, K2HPO4, NaNO3, NaCl, MgSO4.7H2O and culture requirements such as incubation time, inoculum size, medium volume and inoculum age on dextranase production was evaluated by Plackett–Burman design. The most significant factors were further optimized using Box–Behnken design. The model predicted a dextranase activity of 438.15 U/ml when dextran concentration, medium volume and incubation time were 2.1 g/l, 52.47/250 ml flask and 80.48 h, respectively. Verification of the model showed that dextranase production of 440 U/ml was observed under the optimal condition confirming the validity of the model.