Chizuru Sasaki

Surface carbohydrate analysis and bioethanol production of sugarcane bagasse pretreated with the white rot fungus, Ceriporiopsis subvermispora and microwave hydrothermolysis

Effects of pretreatments with a white rot fungus, Ceriporiopsis subvermispora, and microwave hydrothermolysis of bagasse on enzymatic saccharification and fermentation were evaluated. The best sugar yield, 44.9 g per 100g of bagasse was obtained by fungal treatments followed by microwave hydrothermolysis at 180°C for 20 min. Fluorescent-labeled carbohydrate-binding modules which recognize crystalline cellulose (CjCBM3-GFP), non-crystalline cellulose (CjCBM28-GFP) and xylan (CtCBM22-GFP) were applied to characterize the exposed polysaccharides. The microwave pretreatments with and without the fungal cultivation resulted in similar levels of cellulose exposure, but the combined treatment caused more defibration and thinning of the plant tissues. Simultaneous saccharification and fermentation of the pulp fractions obtained by microwave hydrothermolysis with and without fungal treatment, gave ethanol yields of 35.8% and 27.0%, respectively, based on the holocellulose content in the pulp. These results suggest that C. subvermispora pretreatment could be beneficial part of the process to produce ethanol from bagasse.

Epoxy resin synthesis using low molecular weight lignin separated from various lignocellulosic materials.

A low molecular weight lignin from various lignocellulosic materials was used for the synthesis of bio-based epoxy resins. The lignin extracted with methanol from steam-exploded samples (steaming time of 5 min at steam pressure of 3.5 MPa) from different biomasses (i.e., cedar, eucalyptus, and bamboo) were functionalized by the reaction with epichlorohydrin, catalyzed by a water-soluble phase transfer catalyst tetramethylammonium chloride, which was further reacted with 30 wt% aqueous NaOH for ring closure using methyl ethyl ketone as a solvent. The glycidylated products of the lignin with good yields were cured to epoxy polymer networks with bio-based curing agents i.e., lignin itself and a commercial curing agent TD2131. Relatively good thermal properties of the bio-based epoxy network was obtained and thermal decomposition temperature at 5% weight loss (Td5) of cedar-derived epoxy resin was higher than that derived from eucalyptus and bamboo. The bio-based resin satisfies the stability requirement of epoxy resin applicable for electric circuit boards. The methanol-insoluble residues were enzymatically hydrolyzed to produce glucose. This study indicated that the biomass-derived methanol-soluble lignin may be a promising candidate to be used as a substitute for petroleum-based epoxy resin derived from bisphenol A, while insoluble residues may be processed to give a bioethanol precursor i.e., glucose.

Effective enzyme saccharification and ethanol production from Japanese cedar using various pretreatment methods.

We investigated an effective method for the pretreatment of Japanese cedar for efficient enzymatic saccharification and ethanol production. A 45-atm steam explosion provided a comparatively large amount of glucose and reducing sugars. Addition of polyethylene glycol (PEG) influenced the digestibility of holocellulose in a 35-atm steam-exploded sample. However, we observed a negative effect on enzymatic saccharification when sodium hydroxide was used in the pretreatment. The maximum values of glucose and reducing sugars produced using consecutive pretreatments with a 25-atm steam explosion and an ionic liquid were 408 and 462 mg/(g initial dry sample), respectively. The most positive effects on the enzymatic saccharification kinetics were observed when the above consecutive pretreatment methods were used. However, using the organosolv treatment of wood chips without the steam explosion is a more cost-effective pretreatment method for the enzymatic saccharification of Japanese cedar, and this results in 386 and 426 mg/(g initial dry sample) of glucose and reducing sugars, respectively.

Characterization of the steam-exploded spent Shiitake mushroom medium and its efficient conversion to ethanol.

Spent Shiitake mushroom medium was subjected to steam explosion followed by simultaneous saccharification and fermentation (SSF) using Meicelase and Saccahromyces cerevisiae AM12. Water extraction of the medium exposed to steam at 20 atm for 5 min enhanced the saccharification rate by about 20% compared to steam-exploded medium before water extraction and resulted in the production of 23.8 g/l ethanol from a substrate concentration of 100g/l. This corresponded to 87.6% of the theoretical ethanol yield, i.e., 15.9 g ethanol was obtained from 100g of spent Shiitake mushroom medium. Spent Shiitake mushroom medium subjected to steam explosion and then water extraction appears to be a candidate for efficient bioconversion to ethanol.

Characterization of microbial poly (ε-l-lysine) by FT-IR, Raman and solid state 13C NMR spectroscopies

Abstract The molecular structure and conformation of microbial poly(e- l -lysine) (M-e-PL) produced by a variant of Streptomyces albulus were studied by means of FT-IR, FT-Raman and solid-state 13C NMR spectroscopies. Vibrational results indicate that M-e-PL assumes a β-sheet conformation in the solid state. Solid state 13C NMR spectra of the crystalline and the amorphous components were observed separately and the degree of crystallinity was estimated to be 63%. A plausible conformation model was proposed.

Direct hydrolysis of cellulose to glucose using ultra-high temperature and pressure steam explosion

Hydrolysis of two cellulosic materials, i.e. microcrystalline cellulose powder (MC) and cuprammonium rayon fiber (BEMCOT), to glucose was carried out by steam explosion treatment with ultra-high temperature and pressure steam aiming at an effective usage of unutilized cellulosic materials. 50 g of cellulosic materials were charged in a sealed reactor (2L) of the steam explosion apparatus kept at steam pressures of 50, 55, 60, and 62 atm for a steaming time of 1 min. The maximum yield of water soluble sugars, 52.8%, was obtained at a steam pressure of 62 atm and a steaming time of 1 min for MC. Furthermore, the maximum yield of water soluble sugars, 67.7%, was obtained at a steam pressure of 60 atm and a steaming time of 1 min for BEMCOT. This water soluble sugars contained 63.1% and 61.0% of glucose, respectively; they are corresponding to 33.3g and 41.0 g of glucose contained in 100g of dry steam-exploded cellulosic material.

Chemical characteristics and enzymatic saccharification of lignocellulosic biomass treated using high-temperature saturated steam: comparison of softwood and hardwood.

This study investigated the effect of high-temperature saturated steam treatments on the chemical characteristics and enzymatic saccharification of softwood and hardwood. The weight loss and chemical modification of cedar and beech wood pieces treated at 25, 35, and 45 atm for 5 min were determined. Fourier transform infrared and X-ray diffraction analyses indicated that solubilization and removal of hemicellulose and lignin occurred by the steam treatment. The milling treatment of steam-treated wood enhanced its enzymatic saccharification. Maximum enzymatic saccharification (i.e., 94% saccharification rate of cellulose) was obtained using steam-treated beech at 35 atm for 5 min followed by milling treatment for 1 min. However, the necessity of the milling treatment for efficient enzymatic saccharification is dependent on the wood species.

Conversion of steam-exploded cedar into ethanol using simultaneous saccharification, fermentation and detoxification process

In this study, we investigated the simultaneous saccharification, fermentation and detoxification SSDF process of steam-exploded cedar using a detoxification microorganism, Ureibacillus thermosphaericus A1, to facilitate efficient ethanol production. Steam explosion was applied as a pretreatment before enzymatic saccharification followed by alcohol fermentation. The highest glucose conversion rate was observed in the sample pretreated with a steam pressure of 45atm for 5min. Alcohol production by a heat-tolerant yeast, Saccharomyces cerevisiae BA11, was inhibited strongly by inhibitory materials present in the steam-exploded cedar, such as formic acid, furfural, and 5-hydroxymethylfurfural. The maximum amount of ethanol, i.e., 0.155g ethanol/g dry steam-exploded cedar, which corresponded to 74% of the theoretical ethanol yield, was obtained using the SSDF when U. thermosphaericus A1 degraded the inhibitory materials. A fed batch SSDF culture, in which U. thermosphaericus A1 was used to maintain low concentrations of inhibitory materials, was effective for increasing the ethanol concentration.

Steam explosion treatment for ethanol production from branches pruned from pear trees by simultaneous saccharification and fermentation

This study investigated the production of ethanol from unutilized branches pruned from pear trees by steam explosion pretreatment. Steam pressures of 25, 35, and 45 atm were applied for 5 min, followed by enzymatic saccharification of the extracted residues with cellulase (Cellic CTec2). High glucose recoveries, of 93.3, 99.7, and 87.1%, of the total sugar derived from the cellulose were obtained from water- and methanol-extracted residues after steam explosion at 25, 35, and 45 atm, respectively. These values corresponded to 34.9, 34.3, and 27.1 g of glucose per 100 g of dry steam-exploded branches. Simultaneous saccharification and fermentation experiments were done on water-extracted residues and water- and methanol-extracted residues by Kluyveromyces marxianus NBRC 1777. An overall highest theoretical ethanol yield of 76% of the total sugar derived from cellulose was achieved when 100 g/L of water- and methanol-washed residues from 35 atm-exploded pear branches was used as substrate. Graphical Abstract Amounts of glucose and ethanol produced from steam-exploded branches pruned from pear tree.

Extraction of arbutin and its comparative content in branches, leaves, stems, and fruits of Japanese pear Pyrus pyrifolia cv. Kousui

Arbutin is a tyrosinase inhibitor and is extensively used as a human skin-whitening agent. This study investigated the optimum conditions for extracting arbutin by ultrasonic homogenization from discarded branches pruned from Japanese pear (Pyrus pyrifolia cv. Kousui) trees. The arbutin content was measured in the branches and also in the leaves, stems, fruit peel, and fruit flesh.