A Study of Microalgal Symbiotic Communities with the Aim to Increase Biomass and Biodiesel Production

Claus Baggesen

Research output: Book/ReportPh.D. thesis

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Microalgae are nearly everywhere and they are responsible for a large part of the world’s primaryproduction.Their ability to grow fast and toreach high cell densities makes them candidates for use in the production of biofuel. A key feature of many algae is the production of lipids as storage molecules. A variety of algae can produce large amounts of lipids and these easily be converted to biodiesel for use as transport fuel. Production of algal based biodiesel is however still limited mainly due production costs. Research is needed in order to lower the price of the final product. In this study interactions between algae and bacteria have been investigated. Many previous investigations have revealed that algae when co-cultured with bacteria reach higher cell numbers and exhibit faster growth rates. Part of the study focuses on interactions between the green algae Dunaliella salina and three strains of bacteria, Pelagibaca, Halomonas and Marinobacter, isolated from the algal culture. Growing axenic D. salina in co-culture with the bacteria results in markedly higher cell densities. Another part of the study focuses on interactions between three strains of Scenedesmus like algae,isolated water samples obtained locally, and bacteria from one of the water samples. Interestingly the three closely related algae react very differently to being co-cultured withthe bacteria. One algal strain is unaffected, one is promoted in growth, and one is negatively affected.In the final part of the study the effect of hypo and hyper-saline shock on D. salina was investigated. Theoretically D. salina would produce lipids when stressed however no appearance of lipids was detected in the cells subjected to a hypo-saline shock and in the case of a hyper-saline shock lipids could be detected early on but disappeared within 48 h.
Original languageEnglish
PublisherTechnical University of Denmark, Department of Chemical and Biochemical Engineering
Number of pages92
ISBN (Print)978-87-93054-65-3
Publication statusPublished - 2014

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