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Microbial population dynamics in fermented pig feed
Environmental and economic reasons motivate focused research on biofuel production. The new research programme MicroDrivE – Microbially Derived Energy, offers a series of MSc projects within bio-preservation, enzymatic pre-treatments, ethanol fermentation, bioprocessing of byproducts, biogas production and fertility effects of bioresidues. The projects are supervised by scientists from the Departments of Microbiology, Molecular Biology, and Chemistry at the Swedish University of Agricultural Sciences (SLU), Uppsala. MicroDrivE cooperates with a number of biotech and bioenergy companies. For information on the other MSc projects use the search function ”Fritext” to search for MicroDrive.
Liquid pig feed consists of a diet prepared either from a mixture of liquid food industry residues and conventional dry feeds, or from dry raw materials mixed with water. This mixture is then incubated for several days, which results in a fermentation process involving the development of a certain microbial population. Beside of using waste materials for meet production and thus improving the environmental balance of the whole process, feed fermentation also leads to a higher nutritional value of the feed and suppresses the development of harmful microorganisms. However, due to the spontaneous character of the fermentation the effects of using liquid feed are not completely predictable. We performed an analysis of the microbial dynamics and diversity in fermentation processes with different materials and at different temperatures, with a special focus on yeasts and lactic acid bacteria. Using lactic acid bacteria and yeasts isolated from feed fermentations, we will develop a starter culture that can be added to a feed mixture to initiate the fermentation.
In this project, the impact of using this starter culture on a variety of parameters of the feed fermentation will be tested. This will include chemical and nutritional parameters, like the contents of organic acid, phytate, proteins and minerals. We will also investigate the microbial dynamics in the fermentation. This will be done by extracting the microorganisms from the fermentation and cultivating them on media selective for yeasts, moulds, lactic acid bacteria, enterobacteria and general aerobic bacteria. Isolates will be identified by PCR-fingerprinting and sequencing of the according rDNA regions. Fermentations will be performed under different conditions, regarding fermentation temperature and material, which will generate a comprehensive survey about the impacts of the starter culture on stability and predictability of the process.
· Chemical analysis (ICP-AES, HPLC etc.)
· Cultivation of microorganisms, selective growth media, strain conservation
· DNA -isolation, PCR-techniques, gel electrophoresis (GelComparII)
· Sequence analysis using databases and software tools (BLAST, SRS)
We are looking for a student within the microbiology and biotechnology area interested in future technologies for biofuel production and environmental concerns.
For information on the Department of Microbiology, SLU, visit our Web-site: http://www.mikrob.slu.se
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