Efficient conversion of hemicellulose sugars from spent sulfite liquor into optically pure L-lactic acid by
R Hoheneder1, E Fitz2, R H Bischof3
1Department of Wood Chemistry & Biotechnology, Wood Kplus - Kompetenzzentrum Holz GmbH, c/o Muthgasse 18, 1190 Vienna, Austria; Institute of Microbiology and Microbial Biotechnology, Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190 Vienna, Austria.
Abstract:
Spent sulfite liquor (SSL), a waste stream from wood pulp production, has great potential as carbon source for future industrial fermentations. In the present study, SSL was separated into a hemicellulose derived sugar syrup (HDSS) and a lignosulfonic fraction by simulated moving bed chromatography. The recovery of SSL sugars in the HDSS was 89% and the fermentation inhibitors furfural, 5-hydroxymethylfurfural and acetic acid were removed by 98.7%, 60.5% and 75.5%, respectively. The obtained sugars have been converted to L-lactic acid, a building block for bioplastics, by fermentation with the lactic acid bacterium Enterococcus mundtii DSM4838. Batch fermentations on HDSS produced up to 56.3 g/L L-lactic acid. Simultaneous conversion of pentose and hexose sugars during fed-batch fermentation of wildtype E. mundtii led to 87.9 g/L optically pure (>99%) L-lactic acid, with maximum productivities of 3.25 g/L.h and yields approaching 1.00 g/g during feeding phase from HDSS as carbon source.
