Browsing by Subject "Bioremediation."
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Item Open Access Cost-effective production of biological materials for food applications(Bilkent University, 2012) Han, DirenThis thesis consists of two chapters; in the first chapter response surface optimization of the production of a potential probiotic strain was studied by using bioreactors and in the second chapter screening of biosurfactant producing microorganisms was carried out followed by the purification and characterization of the biosurfactant produced. Probiotics are live microorganisms that when administered in adequate amounts are favorable to their host. They are used on livestock to enhance the growth of animals, improve the efficiency of feed conversion and to decrease mortality rate. Therefore, it is important to produce these microorganisms in high amounts. However, process economics is a problem in large scale production of the microorganisms. Main factors that affect the process economics are the growth medium of the organism and the process conditions. Therefore, optimizing the composition of the growth media and cultivation conditions are of crucial importance in large scale production. In this study, optimization of growth media composition and cultivation conditions of a novel probiotic strain, Bacillus pumilus STF26, was done. Factors optimized were temperature, pH and the concentrations of dextrose as carbon source, yeast extract as nitrogen source, KH2PO4 and MgSO4.7H2O. Response surface methodology was used to optimize the parameter and the optimum values are found to be 30.9 °C, 6.9, 20 % (w/v), 1.526 % (w/v), 0.1 % (w/v) and 0.5 % (w/v) for temperature, pH and the concentrations of dextrose, yeast extract, KH2PO4 and MgSO4.7H2O, respectively. Maximum biomass at optimum conditions was 10.42 g/L which is nearly 2.5 times higher when compared to the one obtained by using LB medium at optimized temperature and pH values. In the second chapter, production and characterization of a biosurfactant produced by a novel strain of Staphylococcus xylosus, STF1, was studied. Biosurfactants are surface active agents that have a broad range of applications in different industries and they have several advantages over their chemically synthesized counterparts. However, they cannot compete economically with synthetic surfactants due to their high production cost, the difficulties in downstream processing and the lack of overproducing strains. In this study a novel strain that produces biosurfactant, STF1, was isolated and the biosurfactant was characterized by using mass spectrometry and Fourier transform infrared (FTIR) spectroscopy. FTIR results indicated the lipopeptide nature of the biosurfactant produced by this strain. Moreover, the mass of the purified biosurfactant was 931.9550 (m/z).Item Open Access Novel biological materials for food and environmental applications(Bilkent University, 2012) Umu, Özgün Candan OnarmanProbiotics are microorganisms that have many health benefits to their host, such as promoting normal intestinal microflora, inhibiting the growth of pathogenic microorganisms, improving digestion and stimulation of gastrointestinal immunity. Probiotic microorganisms include bacteria, fungi and yeast, and they are highly desirable to be used as animal feed supplements. For this application, Bacillus species are preferred since they are resistant to extreme environmental conditions due to their spore-forming capacity in addition to having other important probiotic characteristics. In the first chapter of this study, 84 independent bacterial colonies were obtained from different bovine chyme samples and among them 29 were determined as belonging to genus Bacillus. These isolates were principally screened for their antimicrobial activity against a group of selected bacteria including pathogenic organisms such as Salmonella enterica, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. 7 strains (STF4, STF8, STF9, STF10, STF15, STF25 and STF26) with highest antimicrobial activity were further tested for other probiotic properties. They were resistant to the gastrointestinal conditions and most of the antibiotics tested. In addition, they were checked for the presence of plasmids and performed cytotoxicity tests. We propose novel Bacillus strains that have potential to be used as probiotic organisms. TNT is a hazardous nitroaromatic compound that can be found in soil, sediment and water due to extensive contamination from military munitions after the World War II. It has many negative health effects on almost all of the living organisms (e.g. bacteria, fungi, algae, animal and human). So far, bacteria, fungi and plants are commonly used for biodegradation process but only a little is known about effect of algae on this issue. However, algae can be used as a good alternative for bioremediation and biosensor purposes as they do not require advance technology and are effective in terms of cost. 5 different microalgae strains (STA1, STA2, STA3, STA4 and STA5) were tested in terms of survival in different TNT concentration and biodegradation capability of TNT. These strains were isolated from water contaminated with TNT obtained from the Brass Factory affiliated with Mechanical and Chemical Industry Corporation (MKE) located in Kırıkkale, Turkey. Even though these strains did not use TNT as carbon source for growth; they utilize it at different degrees for other metabolic activities. Moreover, the growth of STA2 strain was not inhibited by high TNT concentrations (up to 50 mg/L TNT).Item Open Access Remediation of anionic surfactants and ammonium by biological materials(Bilkent University, 2012) Sarıoğlu, Ömer FarukSurfactants are the main components in detergents and they are primarily discharged from household and industry. Ammonia (or ionized form ammonium) is a byproduct of animal and human metabolism and it is formed in and discharged from aquaculture. Contamination of soil and water sources by surfactants and ammonium is becoming a big problem because of their harmful effects. These substances are highly toxic to many organisms, leading to possible mass deaths in the freshwater ecosystem. As their presence causes a potential environmental risk, industrial and household wastewater systems should be adequately treated to reduce the concentration of ammonium and surfactants. Chemical and biological methods are primarily used to treat wastewater systems. Biological treatment methods are more eco-friendly in comparison to chemical methods. Among biological treatment methods, the use of specific bacteria strains for removal of chemical contaminants is a widely applied process for treatment of industrial and municipal wastewater. However, those bacteria may not be capable of withstanding harsh environmental conditions or they may not specifically degrade the contaminant of interest, so isolation of bacterial strains more resistant to environmental extremes and more suitable for bioremoval is a possible strategy to improve current wastewater treatment strategies. By isolating bacteria well-adapted to the environmental and physical conditions of the system to be cleaned, very high efficiencies can be obtained for wastewater cleaning. To this end, a two-step approach was used. In the first part of this project, our aim was to find an integrated efficient biological based method to clean up industrial wastewater from anionic surfactants. Two main strategies were utilized to solve this problem: Finding and applying a more biodegradable and eco-friendly detergent alternative, and developing a biological treatment method specific for the anionic surfactants in the wastewater system of interest. It is expected that, by combining these two strategies, anionic surfactants in wastewater can be removed more efficiently. In the second part of this project, a novel bacterial strain, which we termed STB1, was isolated from a commercial sea bass farm and found to display high heterotrophic ammonium removal characteristics. The species identity of STB1 was determined to be Acinetobacter calcoaceticus. We evaluated ammonium removal characteristics of STB1 at varying ammonium concentrations, and observed that STB1 can almost completely remove ammonium at low (50 mg/l) and medium (100 mg/l) concentrations within 72 h, while 45% ammonium removal was observed at a higher concentration (210 mg/l) during the same time period. Trace amounts of metabolized ammonium was converted to nitrite or nitrate and 22.16% of ammonium was introduced to cell biomass, while 4.34% of total nitrogen was initially incorporated into biomass and subsequently released to the supernatant fraction in the 100 mg/l sample. Most of the remaining conversion products are expected to be gaseous denitrification products. Toxicological studies with Artemia salina (brine shrimp) nauplii revealed that STB1 strain is non-toxic to Artemia larvae, which suggests that STB1 can be safely and efficiently utilized for water quality enrichment in aquatic ecosystems.Item Open Access Sustainable production of biological materials for food and agricultural applications(Bilkent University, 2013) Angün, PınarMicroalgae are planet’s primary biological CO2/O2 converters. Today, microalgae are used in a wide range of areas; such as waste-water treatment, production of protein-rich food and feed additives, high value added compounds, carotenoids and biofuels. Nowadays, there is an increasing need for renewable energy sources, specifically biofuels due to the depletion of limited fossil fuels. For this purpose, microalgae have emerged as a promising third-generation biofuel source and present possible solution to energy problems. In the first part of this study, the aim was to determine and compare the effects of sulfur (S) and nitrogen (N) starvation on triacylglycerol (TAG) accumulation, which is used as a biodiesel feedstock, and related parameters in wild type Chlamydomonas reinhardtii CC-124 mt(-) and CC-125 mt(+) strains to improve the biodiesel production capacity. Cell division was interrupted, protein and chlorophyll levels rapidly declined while cell volume, total neutral lipid, carotenoid and carbohydrate content increased in response to nutrient deprivation. Microalgae under nutrient starvation were monitored by threedimensional confocal laser imaging of live cells and by transmission electron microscopy (TEM). FTIR measurement results showed that relative TAG, oligosaccharide and polysaccharide levels increased rapidly in response to nutrient starvation, especially in S starvation. Neutral lipid, TAG and carbohydrate levels reached their peak values following four days of N or S starvation. However considering that four days of S deprivation leads to an increased total biovolume and stimulates more lipid and carbohydrate accumulation, S starvation seems to be a better way of stimulating biodiesel feedstock production of wild type C. reinhardtii compared to N starvation. Carotenoids are lipid soluble compounds that play important role in acting provitamin-A, color materials and antioxidants that protect cells and tissues from free radicals and singlet oxygen. In nature, approximately 700 carotenoids have been isolated and characterized. However, there are some disadvantages of natural carotenoids such as being unsustainable and non-economic. Microalgae could serve sustainable solution to the production of natural carotenoids. The aim of the second part of this study was to identify new sources of natural, sustainable and inexpensive carotenoids and antioxidants from 12 isolated microalgae by determining their total carotenoid contents and antioxidant activity. These 12 microalgae were isolated from different water sources in Turkey. Results of this study demonstrated that among 12 microalgae strains, STA2, STA3 and STA9 contained substantial amounts of carotenoids in their metabolism and these carotenoids extracts showed strong antioxidant activity. With the ease of cultivation and high growth rate, these three microalgae strains have potential to use as natural and sustainable carotenoids for food, dietary supplement, pharmaceutical, cosmetic, feed and other related applications.