Sequential Hydrothermal HCl Pretreatment and Enzymatic Hydrolysis of Saccharina japonica Biomass

Abstract

This study investigated the production of fermentable sugars from carbohydrate-rich macroalgae Saccharina japonica using sequential hydrolysis (hydrothermal acid pretreatment and enzymatic hydrolysis) to determine the maximum reducing sugar yield (RSy). The sequential hydrolysis was predicted by three independent variables (temperature, time, and HCl concentration) using response surface methodology (RSM). Enzymatic hydrolysis (8.17% v/wbiomass Celluclast® 1.5 L, 26.4 h, 42.6 °C) was performed after hydrothermal acid pretreatment under predicted conditions (143.6 °C, 22 min, and 0.108 N HCl concentration). Using this experimental procedure, the yields of hydrothermal acid pretreatment, enzymatic hydrolysis, and sequential hydrolysis were 115.6 ± 0.4 mg/g, 117.7 ± 0.3 mg/g, and 183.5 ± 0.6 mg/g, respectively. Our results suggested that sequential hydrolysis of hydrothermal acid pretreatment and enzymatic hydrolysis was more efficient than their single treatment.

Use of macroalgal waste from the carrageenan industry as feedstock for the production of polyhydroxybutyrate

“…Similar conclusions have been obtained by other authors. Thus, a study performed on the brown macroalga Saccharina japonica for the production of reducing sugars by sequential hydrothermal acid pretreatment and enzymatic hydrolysis, showed that HCl concentrations in the range of 0.05–0.1 mol L −1 and short pretreatment times (16–22 min) had little effect on the reducing sugars yield, even though the pre‐treatment was carried out at a fixed temperature of 150°C 26 …”

“…Thus, a study performed on the brown macroalga Saccharina japonica for the production of reducing sugars by sequential hydrothermal acid pretreatment and enzymatic hydrolysis, showed that HCl concentrations in the range of 0.05-0.1 mol L −1 and short pretreatment times (16-22 min) had little effect on the reducing sugars yield, even though the pre-treatment was carried out at a fixed temperature of 150°C. 26 Nevertheless, the pretreatment in these conditions leads to a significant improvement in the RS generated at the hydrolysis stage. In this sense, for the assays mentioned above, the mean value of RS generated in the hydrolysis was 5.20 ± 0.51 g L −1 while the non-pretreated sample reached 2.10 ± 1.59 g L −1 .…”