title: Lipid production from hemicellulose with Lipomyces starkeyi in a pH regulated fed-batch cultivation.
abstract: This study investigated lipid production from the hemicellulosic fraction of birch wood by the oleaginous yeast Lipomyces starkeyi. Birch wood chips were thermochemically pretreated by hot water extraction, and the liquid phase, containing 45.1 g/l xylose as the major sugar, 13.1 g/l acetic acid and 4.7 g/l furfural, was used for cultivations of L. starkeyi CBS1807. The hydrolysate strongly inhibited yeast growth; the strain could only grow in medium containing 30% hydrolysate at pH 6. At pH 5, growth stopped already upon the addition of about 10% hydrolysate. In fed-batch cultures fed with hydrolysate or a model xylose-acetic acid mixture, co-consumption of xylose and acetic acid was observed, which resulted in a pH increase. This phenomenon was utilized to establish a pH-stat fed-batch cultivation in which, after an initial feeding, hydrolysate or model mixture was connected to the pH-regulation system of the bioreactor. Under these conditions we obtained growth and lipid production in cultures grown on either xylose or glucose during the batch phase. In cultivations fed with model mixture, a maximum lipid content of 60.5% of the cell dry weight (CDW) was obtained; however, not all xylose was consumed. When feeding hydrolysate, growth was promoted and carbon sources were completely consumed, resulting in higher CDW with maximum lipid content of 51.3%. In both cultures the lipid concentration was 8 g/l and a lipid yield of 0.1 g/g carbon source was obtained. Lipid composition was similar in all cultivations, with C18:1 and C16:0 being the most abundant fatty acids. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Swedish University of Agricultural Sciences, Department of Chemistry and Biotechnology, BioCentre, Uppsala, Sweden.
authors.forename: Jule
authors.initials: J
authors.lastname: Brandenburg
authors.affiliation: Swedish University of Agricultural Sciences, Department of Chemistry and Biotechnology, BioCentre, Uppsala, Sweden.
authors.forename: Johanna
authors.initials: J
authors.lastname: Blomqvist
authors.affiliation: Swedish University of Agricultural Sciences, Department of Food Science, BioCentre, SLU, Uppsala, Sweden.
authors.forename: Jana
authors.initials: J
authors.lastname: Pickova
authors.affiliation: School of Chemical Engineering, State University of Campinas, UNICAMP, Department of Materials and Bioprocess Engineering, Campinas, Brazil.
authors.forename: Nemailla
authors.initials: N
authors.lastname: Bonturi
authors.affiliation: Swedish University of Agricultural Sciences, Department of Chemistry and Biotechnology, BioCentre, Uppsala, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Sandgren
authors.affiliation: Swedish University of Agricultural Sciences, Department of Microbiology, BioCentre, SLU, Uppsala, Sweden.
authors.forename: Volkmar
authors.initials: V
authors.lastname: Passoth
mesh_terms: D019342:Acetic Acid / Q000032:analysis; D061249:Batch Cell Culture Techniques / Q000379:methods*; D029662:Betula / Q000737:chemistry; D019149:Bioreactors; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D005227:Fatty Acids / Q000032:analysis; D005662:Furaldehyde / Q000032:analysis; D005947:Glucose / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008055:Lipids / Q000096:biosynthesis* / Q000737:chemistry; D055160:Lipomyces / Q000254:growth & development / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D008055:Lipids; D011134:Polysaccharides; C007916:hemicellulose; D014994:Xylose; D005662:Furaldehyde; D005947:Glucose; D019342:Acetic Acid
keywords: Lipomyces starkeyi; biofuels; hemicellulose; lignocellulose; lipids; oleaginous yeasts