فصلنامه زیست فناوری میکروبی
پیاپی 10 (پاییز 1390)

Product reduction results from pathogenic fungi during crop cultivation could be considered the main economic losses factor. Streptomyces spp. has been a widely exploited group of microorganisms in the production of secondary metabolites and commercially important enzymes in agricultural applications. Chitinase enzymes have been used as a potent biocontrol agent. Chitinase C produced by Streptomyces griseus was the first family of 19 chitinase found in an organism other than higher plants. The antifungal activity of bacterial chitinase19 is higher than the others. It possesses high antifungal activity and strong hydrolyzing property against chitin. In this study we investigated the antifungal potential of the Streptomyces griseus bacteria, incubation period on the chitinase production and effect of pH and temperature on chitinase19 activity, to achieve optimal conditions for the enzyme activity in this bacterium. Methods of research: In the present study, the samples were isolated from soils of different areas of kordestan and Ardebil provinces. Chitinase 19 producing strains were screened using specific primers. A suitable strain of streptomyces griseus was selected. The Crude enzyme extract from the bacterial culture was purified and its effects were measured on colloidal chitin in different temperature and pH conditions. Chitinase production started a day after incubation and reached to maximum levels after 5 days. Optimum pH and temperature for enzyme activity were 6 and 37 ºC, respectively. In the dual culture test on PDA medium, an inhibitory effect of Streptomyces griseus against pathogenic fungal phytophthora sp. 44D and Fusarium solani were observed. In conclusion, our results showed that chitinase C could be used as a biocontrol agent.

Poly-beta-hydroxyl butyrate, (PHB) is a biodegradable thermoplastic which can be extracted from a wide range of bacteria as intracellular granules. They are used in packaging, medicine and agriculture. The purpose of this study was optimization of medium components and culture conditions in order to improvement of PHB production by Bacillus subtilis ATCC 6633.Methods of research: At first, the effects of different carbon and nitrogen sources and incubation times in production were optimized by one- factor- at- a- time method. Then optimization of the best nutritional sources was performed. Firstly the effect of various carbon sources such as glucose, sucrose, arabinose, monnitol and starch were studied. Then the various mineral and inorganic nitrogen sources such as glycine, cysteine, ammonium sulphate and potassium nitrate were studied on PHB production by Bacillus subtilis ATCC 6633. The results showed that amongest of the carbon sources, starch was the best carbon sources and Amongest of variety nitrogen sources, ammonium sulphate as mineral source and glycine as inorganic source were known as the best sources. The best concentration and time for starch and ammonium sulphate to PHB production were 48 hours and 5% (v/v), and for glycine were 48 hours and 3% (v/v) respectively. Consequently among the (1-8) % of carbon and nitrogen sources, the concentration of (2-5)% had the most production.

Aspergillus spp can cause various diseases including: invasive aspergillosis(IA), chronic necrotizing aspergillosis, aspergilloma and allergic bronchopulmonary aspergillosi. Most case of IA caused by Aspergillus fumigatues. Aspergillus flavus being often reported as the second most frequent species. Nosocomial infections occur worldwide. They are important contributors to morbidity and mortality and aspergillus fumigatus play an important role in these infections. Clinical microbiology laboratories in tertiary-care hospitals should be able to perform epidemiological analysis and surveillance of aspergilla in a hospital environment on routine basis. We collected samples of air from outdoor and indoor environment in the hospital in summer, autumn, winter and spring. Czapeck agar plates were used as culture medium. Among the methods suitable for identification RAPD offers the best potential in terms of obtaining discriminatory data in a rapid simple and cost-efficient way. The autumn collection yielded more isolates than that of the other seasons. Several RAPD primers and protocols have been published for using in different species of the genus Aspergillus. Among the primers tested R108 show an unequivocal differentiation of Aspergillus fumigatus and Aspergillus flavus. A reliable simple and rapid molecular method with high discriminatory power is necessary for identifying the molecular pattern of each species.

Passing through the micro-particles to nano-particles domain, encountered to some physical changes, such as, increasing the surface area to volume ratio and appearing of quantum effects. Increasing the surface area to volume ratio results in gradual decrease of particle size and overcoming the surface atoms to inner atoms behavior. The most particular purpose of nanotechnology is the improvement of methods for producing nanostructures without using of toxic material, with less expense and wastage with controlling of size. Biologists knowing of producing of minerals in nanoscales by organisms are looking for biologic systems for synthesizing of inorganic nanoparticles. The purpose of this study, was synthesizing of Silver nanoparticles by fungus Fusarium oxusporum IRAN 81C with extreme size of 50 nm. After optimizing of growth condition in culture MGYP media contains Glucose 10 g/l, peptone 5g/l, yeast extract 3g/l and malt extract 3g/l, biomass of Fusarium oxusporum was prepared. After synthesizing of nanoparticles in solution of silver nitrate, FTIR, UV-vis spectrophotometer and TEM was done. The results of this analyses showed that in concentration of 10-³ M, biomas of Fusarium oxusporum IRAN 81C could synthesis of Silver nanoparticles extracellularly. As well as, it’s clear that after filtration of fungal cell mass, the supernatant has ability to synthesis of silver nano-particles because the production of some proteins and enzymes in the culture medium. Silver nanoparticles with extraordinary physical and chemical properties of Silver nanoparticles with size of 50 nm by Fusarium oxusporumm, studding on its functional production in industrial scale is suggested.

Staphylococcus aureus is resistant to many commonly used antibiotics. Different studies have shown that herbal ingredients such as epigallocatechin gallate (EGCG), and a delivery drug system such as nanoliposomes could kill antibiotic-resistant bacteria. The objective of this study was to prepare and evaluate in vitro anti- staphylococcus aureus efficacy of prepared EGCG-loaded nanoliposomes. EGCG-loaded nanoliposomes with negative surface charge were prepared by reverse phase evaporation method. For preparation of nanoliposomes lecithin, cholesterol and dicetyl phosphate were used. Then, the EGCG encapsulation efficacy was measured by spectrophotometric. The minimum inhibitory concentration (MIC) of EGCG-loaded nanoliposomes for resistant strain of Staphylococcus aureus were determined by broth dilution method. Ultimately, the killing rate of Staphylococcus aureus was exposed to MIC concentration of EGCG in free and nanoliposomal form was analyzed. The encapsulation efficacy for EGCG-loaded nanoliposomes was to 75%±0.31. The MIC of free and nanoliposomal form of EGCG against resistant strain of Staphylococcus aureus was to 50 and 25 mg/l, respectively. Also the killing rate of EGCG-loaded nanoliposomes was higher than those of free EGCG at identical times. Our data suggest that the prepared EGCG-loaded nanoliposomes because of high effectiveness would be a choice appropriate for treatment of Staphylococcus aureus infections.

Toxic gases are one of important parameters in water and high concentration of these factors is caused problems in aquatic organisms. In warm water farms, decreasing of dissolved oxygen and pH are caused increasing of SH2 concentration. One of decreasing methods of SH2 is use of oxidizing bacteria. The aim of this study, isolation of sulfur oxidizing bacteria those are able to growth in aerobic and anaerobic and neutral pH and also reducing of nitrogen in different forms. After sampling of water and sediment, culture was done in T2 medium and nutrient broth included sodium sulphite. Samples were incubated at 25-30 o C for 4-6 days. Final culture from positive tests, were done in T2 medium agar (15% agar agar) and nutrient agar included sodium sulphite. Microscopy, microscopy characterization and biochemical tests were done for isolated colonies. Evaluation of sulfur oxidation in various scale (bench, aquariums, fiberglass and farm) were done in different time. Effects of pH, aeration and sodium sulphite on different treatments were also surveyed. The results were showed that two sulfur oxidizing bacteria including Tiobacillus denitrificans and Paracoccus denitrificans were isolated that are able to growth in pH 7-8 and 25-30 o C and be and not to be of aeration was any effect on examination. The conclusion was showed that isolated of bacteria with other bacteria such as nitrosomonas and nitrobacter are able to decrease combination of ammonia, nitrite and SH2.

Aspergillus niger is one of the important symbiotic fungus of tea leaves. The fungal extracellular cellulase could be used as a cellulolytic agent during tea processing. Tea is the most consuming beverage in the world and different qualities are due to complex metabolic pathways occurring during fermentation process so investigation of tea fungal enzyme effects as an important part of fermentation is valuable. The final goal of this research is investigation of cellulolytic effects of fungal enzymes on tea leaves in order to improvement of tea quality factors. The cellulase enzymes isolated from Aspergillus niger was used for fermentation of tea leaves. The somogyi–nelson assay was used to determine enzyme activity. Other parameters such as Km and Vmax, optimum amounts of pH and temperature and finally thermo stability of enzyme was determined and compared with two other enzyme samples. Effects of both crude enzyme preparation and purified cellulase enzymes on the improvement of tea leaf fermentation were determined in terms of theaflavin, thearubigin, total liquor color and dry matter content of the tea produced. Enzyme specific activity and total protein as well as evaluated quality factors of tea was observed to increased by using more purified preparation of enzyme. The crude enzyme preparations obtained from ethanol precipitation were found to be more effective in improving tea leaf fermentation than crude extract of enzyme preparation.

Nowadays, increasing antibiotic resistant in bacterial strains, identification and introduction of antimicrobial compounds with herbal origin is very important. Vast area of our country gardens has allocated by Pistacia vera. In this study antibacterial activity of methanolic extracts of Pistacia vera epicarp was studied in vitro condition. In this study methanolic extract of Pistacia vera epicarp provided by maceration method. The antibacterial activity of extract was evaluated against: Staphylococcus epidermidis, Staphylococcus aureus, Enterococcus faecalis, Streptococcus pyogenes, Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, Proteus vulgaris, by agar diffusion method (disc & well) and broth dilution methods. The extract of Pistacia vera epicarp prevents the growth of bacteria. The MICs effects of methanolic extract were distinguished against positive bacteria as Enterococcus feacalis with 60 µg/µl. and against gram negative bacteria as Pseudomonas aeruginosa was observed by 62.5 µg/µl. The methanolic extract of pistachio green hull contains antibacterial compounds that prevents the growth of gram-positive and Gram-negative bacteria. The Iranian Pistacia vera epicarp, which indicate the presence of active components can be used as a source of cheap and accessible for medicinal purposes.