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dc.contributor.authorEthier, Shannon Elizabethen_US
dc.date.accessioned2014-03-14T20:36:41Z
dc.date.available2014-03-14T20:36:41Z
dc.date.issued2010-05-04en_US
dc.identifier.otheretd-05132010-131949en_US
dc.identifier.urihttp://hdl.handle.net/10919/32716
dc.description.abstractCrude glycerol is a major byproduct if the biodiesel industry. Biodiesel manufacturers are currently facing the challenges of appropriate disposal of this waste material. Crude glycerol is expensive to purify for use in food, cosmetic, and pharmaceutical industries and therefore, alternative methods for use of this crude glycerol are needed. A promising alternative is to use this crude glycerol as a carbon source for microalgae fermentation. In this project, we investigated the use of crude glycerol as a less expensive substrate for the fermentation of the microalgae Schizochytrium limacinum and Pythium irregulare which are prolific producers of omega-3 polyunsaturated fatty acids. Omega-3 fatty acids have many beneficially effects on treating human diseases such as cardiovascular diseases, cancers, and neurological disorders. In addition, the omega-3 fatty acids docosahexaenoic acid (DHA) has been shown to be an important factor in infant brain and eye development. The first part of this study focused on the continuous fermentation of S. limacinum, a prolific producer of DHA. The objective of this study was to examine the algal cellular physiology and maximize its DHA productivity. Two important parameters used in continuous fermentation were studied: dilution rate (D) and feed glycerol concentration (S0). The highest biomass productivity of 3.88 g/L-day was obtained at D = 0.3 day-1 and S0 = 60 g/L, while the highest DHA productivity (0.52 g/L-day) was obtained at D = 0.3 day-1 and S0 = 90 g/L. The cells had a true growth yield of 0.283 g/g, a maximum specific growth rate of 0.692 day-1, and a maintenance coefficient of 0.2216 day-1. The second part of this study focused on morphology issues with P. irregulare, a prolific producer of eicosapentaenoic acid (EPA). P. irregulare has a filamentous morphology, which can make fermentation difficult. The mycelium can stick to the agitation blades resulting in mechanical problems. In addition, this filamentous morphology prevents adequate amounts of oxygen from reaching some cells resulting in decreased productivities. The focus of this research was to control the fermentation conditions to make the algae grow in small pellets, a morphology more suitable for fermentation. In flask culture studies, pellets were formed at an agitation speed of 110 rpm in both regular and baffled flasks. Baffled flasks resulted in pellet formation at 90 and 130 rpm as well. Fermentation studies resulted in pellet formation at agitation speeds of 150 and 300 rpm. Pellets were better able to form when a baffle was not in place. In addition, agitation speed influenced pellet size, with smaller pellets forming at the higher agitation speed. Overall, this study showed that crude glycerol can be used as a carbon source for the continuous fermentation of S. limacinum with high DHA productivity and the morphology of P. irregulare could be controlled by manipulating culture conditions, mainly agitation speed. These results show the potential for scale-up studies for both algal species.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartEthier_SE_T_2010.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectbiodieselen_US
dc.subjectcrude glycerolen_US
dc.subjectdocosahexaenoic aciden_US
dc.subjecteicosapentaenoic aciden_US
dc.subjectfermentationen_US
dc.subjectmicroalgaeen_US
dc.subjectmorphologyen_US
dc.titleProducing Omega-3 Polyunsaturated Fatty Acids from Biodiesel Waste Glycerol by Microalgae Fermentationen_US
dc.typeThesisen_US
dc.contributor.departmentBiological Systems Engineeringen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
dc.contributor.committeechairWen, Zhiyouen_US
dc.contributor.committeememberZhao, Bingyuen_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05132010-131949/en_US
dc.contributor.committeecochairVaughan, David H.en_US
dc.date.sdate2010-05-13en_US
dc.date.rdate2010-06-16
dc.date.adate2010-06-16en_US


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