Browsing by Subject "microalgae"
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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 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.