Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Effect of the Morphology of Aspergillus Sojae on Pectinase Enzyme and the Optimization of Fermentation Conditions(Izmir Institute of Technology, 2006) Göğüş, Nihan; Tarı, CananThe control of the morphology of fungi needs great attention for the optimal potential production of the product. For this purpose Aspergillus sojae ATCC 20235, which has no available literature report on the pectinase production, is used as a model in the determination of the optimum regions for maximum polygalacturonase synthesis and biomass formation with desired pellet morphology by using low cost carbon and nitrogen sources. Firstly, a full factorial statistical design, with the factors of, two taxonomically different strains, seven types of seed culture formulations (slants) and two types of fermentation media were used to investigate the effect of these parameters on the polygalacturonase (PG) production. According to statistical analysis, factors of strain types and fermentation media and the interaction between them were found significant on the enzyme activity. Aspergillus sojae in a complex media, inoculated with a seed culture prepared from molasses resulted in maximum PG activity (0.2 U/ml). Then, a two step optimization procedure with four factors (concentrations of maltrin and corn steep liquor (CSL), agitation speed and inoculation ratio) was used to investigate the effect of these parameters on the PG activity, mycelia growth (biomass) and morphology (pellet size) of Aspergillus sojae. According to the results of response surface methodology (RSM), concentrations of maltrin, CSL and agitation speed were significant (p<0.05) on both PG synthesis and biomass formation. As a result, maximum PG activity (13.5 U/ml) was achievable at high maltrin (120 g/l), low CSL (0 g/l), high agitation speed (350 rpm) and high inoculation ratio (2x107 total spore). The diameter of pellets ranged between 0.05-0.63 cm. The second optimization step improved the PG activity by 74 % and the biomass by 40 %. Furthermore characterization of the enzyme with respect to its optimum pH and temperature and the effect of these on the stability were considered. Determination of the thermal inactivation constant with its inactivation energy and the substrate specificity constant were estimated.Master Thesis Production and Isolation of Fungal Chitosan by Submerged Fermentation(Izmir Institute of Technology, 2003) Alper, Seda; Harsa, Hayriye ŞebnemChitosan is the N-deacetylated derivative of chitin which is the supporting material of crustaceans and insects. Chitosan together with chitin are recommended as suitable functional materials because of their excellent biocompatibility, biodegradability, non-toxicity and adsorption properties and can be used in agriculture, biotechnology and food industry. Although chitosan is produced by chemical deacetylation of chitin molecule, it is also a natural component of cell walls of fungi belonging to Zygomycetes and can be produced by extraction from fungus cell walls. Fungi are thus the promising alternative sources of chitosan. Fungi can be manipulated to give chitosan of more consistent and desired physico-chemical properties compared to chitosan obtained from crustacean sources. In this study, Absidia spp, Aspergillus niger, Rhizopus arrhizus, Cunnighamella elegans, and Mucor rouxii were examined for biomass growth. At first, all five species were grown on synthetic medium at 28 C, 180 rpm in shake-flask incubator. Mucorrouxii which gave the maximum biomass concentration was also grown on molasses. The maximum biomass concentration of Mucor rouxii was found to be higher than that of synthetic medium. The best growth conditions obtained were 4% sucrose, 0.2% yeast extract, 1% peptone and 106 spores in 40 ml. The mycelia harvested at late exponential phase was treated with alkali to remove proteins and chitosan was extracted from cell wall by using acetic acid. The yield of extractable chitosan obtained from cell wall of Mucor rouxii was 2500 mg / l and it is almost 20 % of biomass and approximately 35 % of alkali insoluble fraction.Master Thesis Utilization of Organce Peel Extract for Fungal Enzyme Production(Izmir Institute of Technology, 2013) Genç, Berna; Büyükkileci, Ali OğuzPectinases are a group of hydrolytic enzymes that degrade pectic substances and produced by a variety of microorganisms including filamentous fungi. In previous studies orange peel especially in solid state fermentations was utilized as a source of additional sugars and nutrients. In this study, orange peel, an agro industrial residue was used for exo-polygalacturonase (exo-PG) production in submerged fermentation (SmF) by Aspergillus sojae which have been shown to be a potential exo-polygalacturonase producer. Solubilization of carbohydrates within orange peel was provided by water extraction and treatment with dilute phosphoric (at 0.4% acid concentration and 120 oC in 20 min.) and sulfuric (at 0.5% acid concentration and 116 oC in 13 min.) acid hydrolysis. Phosphoric acid hydrolysis was optimized selecting temperature (oC), time (min.) and acid concentration (v/v %) as variable factors, while reducing sugar concentration (gL-1) was the response factor. Two different dilute acid hydrolysis (at 0.4 % phosphoric acid concentration and 120 0C in 20 min and at 0.5 % sulfuric acid concentration and 116 0C in 13 min.) and water extraction were carried out to obtain media that were utilized for enzyme productions. A.sojae ATCC 20235 and mutant A.sojae strains were used to produce exo-PG in these hydrolysates and water extract of orange peel. To enhance exo-PG production, trace element solutions added as well as macro nutrients. Pellet size, number, density, pH and spore inoculation of fermentation were the other parameters that were controlled during fermentations. The highest exo-PG production was 18.4 UmL-1, which was obtained by mutant A.sojae in phosphoric acid hydrolysate but on the other hand mutant A.sojae produced 19.7 UmL-1 exo-PG activities in water extract of orange peel.Master Thesis Production of Pectinase Enzyme From Aspergillus Sojae Batch and Fed-Batch Systems(Izmir Institute of Technology, 2008) Doğan, Nergiz; Tarı, CananCommercial preparations of pectinases derived from fungi are well known to have high biotechnological value in the industry. For this purpose, polymethylgalacturonase (PMG) and polygalacturonase (PG) were produced with high productivities by Aspergillus sojae ATCC 20235 by using low cost carbon (Maltrin) and nitrogen (Corn Steep Liquor, CSL) sources. There is no literature report to best of our knowledge on the fed-batch production, purification and characterization of polygalacturonase using this microorganism.In this study batch fermentation was carried out in order to obtain the crude PG and to establish a baseline for the forth coming fed-batch experiments. The crude PG was partially purified using three-phase partitioning as an emerging bioseparation technique and characterized with respect to its biochemical and thermal properties. These studies showed that this enzyme holds a great potential to be a good candidate for various industrial applications. To optimize fed-batch fermentation conditions, response surface methodology (RSM) was performed using face-centered central composite design. As a result, maximum PG activity (20.61 U/ml) and maximum biomass (34.23 g/l) were obtained at high maltrin (150 g/l) and high CSL (10 g/l) concentrations when the repeated feeding was done at 48th and 72nd hours. Maximum PMG activity (16.76 U/ml) was also achieved at higher maltrin and higher CSL concentrations at a feeding time of 72nd hours. Fed-batch fermentation has been successfully used to increase PG (33.74%) and PMG (23.96%) activities from Aspergillus sojae. Finally, agar diffusion method was adapted as a rapid method for the selection of high pectinase producer in the strain improvement study.