Metabolic Pathways and Biofuel Production from Lignocellulosic Biomass by Thermophilic Anaerobes isolated from Icelandic Hot Springs

• Main Author: Sara Lind Jónsdóttir 1989-
• Other Authors: Háskólinn á Akureyri
• Format: Thesis
• Language: English
• Published: 2014
• Subjects: Líftækni; Eldsneytisframleiðsla; Lífræn efnasambönd; Iceland
• Online Access: http://hdl.handle.net/1946/18776

The present investigation is, firstly, a literature review of most current studies on biofuel production (e.g. ethanol, hydrogen and methane) from lignocellulosic biomass and the use of the isolated thermophilic anaerobic strains from Icelandic hot springs in the process. Various factors affect the production of biofuels from lignocellulosic biomass including partial pressure of hydrogen, initial concentration of lignocellulosic hydrolysates, acidity and alkalinity of pretreatment, inhibitory effects of end-product formation and enzymes used. Good ethanol and hydrogen yields depend greatly on optimising these factors and the use of the suitable lignocellulosic hydrolysate. Thermoanaerobacterium strain AK17 has the highest ethanol yield of 5.5 mM g sugar-1 from 2.5 g L-1 grass hydrolysate, followed by Thermoanerobacter strain AK5 with ethanol yield of 4.4 mM gsugar-1 from grass hydrolysates. Thermoanaerobacter strain GHL15 has the highest hydrogen yield of 7.6 mM g sugar-1 from grass hydrolysates followed by Clostridium strain AK14 with 6.23 mM g sugar-1 also from grass hydrolysates. Fermentative performance of the methane-producing strains isolated in Iceland is yet to be studied and published. Secondly, biofuel production processes are reviewed in the paper. Several challenges concerning the upscaling and the high cost of pretreatment are presented. Verkefnið er fyrst og fremst heimildarritgerð á nýjustu rannsóknum á lífeldsneytisframleiðslu (etanól, vetni og metan) úr flóknum lífmassa og notkun einangraðra hitakæra baktería úr íslenskum hverum í framleiðsluferlinu. Mismunandi þættir hafa áhrif á lífeldsneytisframleiðslu úr flóknum lífmassa s.s. hlutþrýstingur vetnis, upphafsstyrkur flókins lífmassa, formeðhöndlun með sýru- og basa, hrindrunaráhrif lokaafurða, og ensím sem eru. Góð etanól og vetnisnýting er háð því að hámarka þessa mismunandi þætti og hvaða lífmassi er notaður. Thermoanaerobacterium stofn AK17 hefur hæstu etanól nýtingu 5.5 mM g sugar-1 við 2.5 g L-1 upphafsstyrks úr gras hydrolysati. Næstur ...