sepharose and 5-hydroxymethylfurfural

To obtain fermentable sugar from agarose, pretreatment of agarose by using acetic acid was conducted for short durations (10-30 min) at low acid concentrations (1-5% (w/v)) and high temperatures (110-130 °C). On testing the pretreated agarose by using an endo-β-agarase I (DagA), an exo-β-agarase II (Aga50D), and neoagarobiose hydrolase (NABH), we observed that the addition of the endo-type agarase did not increase the sugar yield. Use of the crude enzyme of Vibrio sp. EJY3 in combination with Aga50D and NABH including acetic acid pretreatment resulted in a 1.3-fold increase in the final reducing sugar yield (62.8% of theoretical maximum based on galactose and 3,6-anhydrogalactose in the initial agarose), compared to those obtained using Aga50D and NABH only after acetic acid pretreatment. The simultaneous saccharification and fermentation of pretreated agarose yielded ethanol of 37.1% theoretical maximum yield from galactose contained in the pretreated agarose.

Topics: Acetic Acid; Biomass; Carbohydrate Metabolism; Carbohydrates; Chromatography, Thin Layer; Ethanol; Fermentation; Furaldehyde; Glycoside Hydrolases; Hot Temperature; Hydrolysis; Seaweed; Sepharose; Vibrio

A two-stage membrane process for the separation of galactose, 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) has been proposed. The first step of nanofiltration (NF) is to remove 5-HMF and LA from galactose solution obtained by the hydrolysis of agarose, the main component of red algal galactan for the reduction of its microbial toxicity. 5-HMF and LA are inhibitory to fermentation but at the same time useful compounds themselves with many applications. The second step of electrodialysis (ED) is to separate 5-HMF and LA in the permeate from NF. More than 91% of 5-HMF and up to 62% of LA could be removed from agarose hydrolysate, while galactose was almost completely retained by NF. Further removal of LA was expected to be possible with no loss of galactose by operating the NF process in a diafiltration mode. 5-HMF and LA could be effectively separated from each other by ED.

Topics: Acids; Dialysis; Electricity; Electrochemistry; Filtration; Furaldehyde; Galactose; Hydrogen-Ion Concentration; Hydrolysis; Levulinic Acids; Membranes, Artificial; Nanotechnology; Pressure; Sepharose; Temperature