Detoxification of lignocellulosic hydrolysates using sodium borohydride

• Published in: Bioresource technology Vol. 136; pp. 368 - 376
• Main Authors: Cavka, Adnan, Jönsson, Leif J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.05.2013; Elsevier
• Subjects: Biofuel production; Biological and medical sciences; Biotechnology; Borohydrides; Borohydrides - pharmacology; Cellulase - metabolism; Cellulose - metabolism; Cellulosic ethanol; Chromatography, High Pressure Liquid; Detoxification; Energy; Enzymes; Ethanol; Ethyl alcohol; Fermentation - drug effects; Fundamental and applied biological sciences. Psychology; Furaldehyde - pharmacology; Hydrolysates; Hydrolysis - drug effects; Industrial applications and implications. Economical aspects; Inhibitors; Lignin - metabolism; Lignocellulose; Mass Spectrometry; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; Picea - drug effects; Picea - metabolism; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - metabolism; Saccharum - drug effects; Saccharum - metabolism; Sodium; Sodium borohydride; Sulfur - metabolism; Inhibitors; Sodium borohydride; Lignocellulose; Cellulosic ethanol; Detoxification; Ethanol; Biofuel; Lignocellulosics; Sodium Tetrahydroborates; Alcoholic fermentation; Hydrolysate; Cellulose derivatives; Inhibitor
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2013.03.014

•Inhibitors in lignocellulosic hydrolysates prevent efficient bioconversion.•A new method for detoxification of lignocellulosic hydrolysates is presented.•Sodium borohydride treatment detoxifies hydrolysates by reduction of inhibitors.•No extra process step required: can be performed as chemical in situ detoxification.•Indicates difference between inhibition of microbes and of enzymes. Addition of sodium borohydride to a lignocellulose hydrolysate of Norway spruce affected the fermentability when cellulosic ethanol was produced using Saccharomyces cerevisiae. Treatment of the hydrolysate with borohydride improved the ethanol yield on consumed sugar from 0.09 to 0.31g/g, the balanced ethanol yield from 0.02 to 0.30g/g, and the ethanol productivity from 0.05 to 0.57g/(L×h). Treatment of a sugarcane bagasse hydrolysate gave similar results, and the experiments indicate that sodium borohydride is suitable for chemical in situ detoxification. The model inhibitors coniferyl aldehyde, p-benzoquinone, 2,6-dimethoxybenzoquinone, and furfural were efficiently reduced by treatment with sodium borohydride, even under mild reaction conditions (20°C and pH 6.0). While addition of sodium dithionite to pretreatment liquid from spruce improved enzymatic hydrolysis of cellulose, addition of sodium borohydride did not. This result indicates that the strong hydrophilicity resulting from sulfonation of inhibitors by dithionite treatment was particularly important for alleviating enzyme inhibition.