Operating the saccharification and fermentation processes at high substrate loadings is a key
factor for making ethanol production from lignocellulosic biomass economically profitable.
However, increasing the substrate loading presents some disadvantages, among them larger
generation of inhibitors, which negatively affect fermentation performance. In this study,
laccase enzymatic treatment was evaluated as a method to reduce these inhibitory effects. The
laccase efficiency was analyzed in a presaccharification and simultaneous saccharification
and fermentation process (PSSF) at different high substrate loadings. Water insoluble fraction
(WIS) from steam-exploded wheat straw was used as substrate and Saccharomyces cerevisiae
as fermenting organism. Laccase supplementation reduced strongly the phenolics content in
the media, without affecting weak acids and furan derivates. It resulted in an improved yeast
performance during simultaneous saccharification and fermentation process, increasing
significantly ethanol productivity.
Duque, Aleta; Manzanares, Paloma; Ballesteros, Ignacio; Negro, Maria José; Oliva, Jose Miguel; Saez, Felicia; Ballesteros, Mercedes(December 12, 2013)
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Resumen:
In this work, an integrated one-step alkaline-extrusion process was tested as
pretreatment for sugar production from barley straw (BS) biomass. The influence of extrusion
10 temperature (T) and the ratio NaOH/BS dry matter (w/w) into the extruder on pretreatment
effectiveness was investigated in a twin-screw extruder at bench scale . A 23 factorial response
surface design of experiments was used to analyze the effect of process conditions [T: 50-
100ºC; NaOH/BS ratio: 2.5-7.5% (w/w)] on composition and enzymatic digestibility of
pretreated substrate. The optimization of these process variables for a maximum glucan to
15 glucose conversion was determined to be at 6% NaOH/DM and 68ºC. At these conditions,
glucan yield reached close to 90% of theoretical, while xylan conversion was 71 % of
theoretical. These values are 5 and 9 times higher than that of the untreated material, which
supports the great potential of this one-step combined pre-treatment technology for sugar
production from lignocellulosic substrates