Improved Glucose Recovery from Sicyos angulatus by NaOH Pretreatment and Application to Bioethanol Production

Abstract

As greenhouse gases and environmental pollution become serious, the demand for alternative energy such as bioethanol has rapidly increased, and a large supply of biomass is required for bioenergy production. Lignocellulosic biomass is the most abundant on the planet and a large part of it, the second-generation biomass, has the advantage of not being a food resource. In this study, Sicyos angulatus, known as an invasive plant (harmful) species, was used as a raw material for bioethanol production. In order to improve enzymatic hydrolysis, S. angulatus was pretreated with different NaOH concentration at 121 °C for 10 min. The optimal NaOH concentration for the pretreatment was determined to be 2% (w/w), and the glucan content (GC) and enzymatic digestibility (ED) were 46.7% and 55.3%, respectively. Through NaOH pretreatment, the GC and ED of S. angulatus were improved by 2.4-fold and 2.5-fold, respectively, compared to the control (untreated S. angulatus). The hydrolysates from S. angulatus were applied to a medium for bioethanol fermentation of Saccharomyces cerevisiae K35. Finally, the maximum ethanol production was found to be 41.3 g based on 1000 g S. angulatus, which was 2.4-fold improved than the control group.

Statistical Optimization of Alkali Pretreatment to Improve Sugars Recovery from Spent Coffee Grounds and Utilization in Lactic Acid Fermentation

“…Pretreatment of biomass, including chemical (alkali, acid and ionic liquid), physical (pyrolysis and steam explosion) and biological (fungi) pretreatment to remove the lignin, have been carried out [18]. The chemical pretreatment using diluted acid or alkaline is preferred due to its high sugar recovery and low cost [19]. Diluted acid pretreatment leads to fermentation inhibitors, including furfural and 5-hydroxymethylfurfural, which are generated by the decomposition of hemicellulose [20].…”

Improvement of Enzymatic Glucose Conversion from Chestnut Shells through Optimization of KOH Pretreatment

“…The recent studies that focus on the optimization of alkali pretreatment are summarized in Table 7. The pretreatment of various biomass such as canola straw, Sida acuta (Thailand Weed), Sicyos angulatus, Miscanthus, bamboo, corncob, walnut shell, corn stover, orange peel and spent coffee ground (SCG) were carried out under the determined conditions using alkali reagents (NaOH, NH 3 and KOH) [17,18,22,[41][42][43][44][45][46]. The reported data such as the solid components and enzymatic digestibility before and after the pretreatments were investigated.…”

“…CNSs were hydrolyzed with 60 filter paper units (FPUs) cellulase/g-biomass and 30 cellobiase units (CBUs) cellobiase/g-biomass at 50 • C for 72 h in a 50 mM sodium citrate buffer (pH 4.8) [22]. One FPU and CBU were defined as the amount of enzyme that released 1 µmol glucose per min under the standard assay conditions.…”

Enhanced Production of Bacterial Cellulose from Miscanthus as Sustainable Feedstock through Statistical Optimization of Culture Conditions

“…The United Nations (UN) has established the United Nations Framework Convention on Climate Change (UNFCCC) and adopted treaties such as the Kyoto Protocol and the Paris Agreement to combat climate change through development goals that require carbon emission reduction [ 1 , 2 , 3 , 4 ]. As a solution, the concept of replacing fossil fuels with biomass which is a sustainable resource has attracted attention [ 1 , 5 , 6 ]. Various studies are being conducted globally to design carbon-neutral platforms that produce value-added materials such as biopolymers, biofuels, and biochemicals using the biorefinery concept [ 1 , 2 , 7 , 8 ].…”