Cellulose-rich Fraction Research Articles

Enzymatic hydrolysis of cellulose-rich fraction of Arctic seaweeds using Penicillium- and Myceliophtora-based glycoside hydrolases

Enzymatic hydrolysis of cellulose-rich fraction of Arctic seaweeds using Penicillium- and Myceliophtora-based glycoside hydrolases

Low-temperature pretreatment by AlCl3-catalyzed 1,4-butanediol solution for producing ‘ideal’ lignin with super-high content of β-O-4 linkages

High contents of internal β-O-4 linkages in lignin are critical for high-yield production of high-value aromatic monomers by depolymerization. However, it remains great challenge due to lack of suitable protection strategy. In this work, a very effective lignin-first strategy was developed to produce ideal lignin with a super high content of β-O-4 linkages (up to 72 %) from poplar, in which the pretreatment was undertaken at low temperatures of 90–130 °C with the use of AlCl3-catalyzed 1, 4-butanediol solution. 2D-HSQC NMR spectra revealed that lignin β-O-4 linkages were protected from etherification of the OH group by 1, 4-butanediol at the α position of lignin aliphatic chains. Besides, the OH groups at the γ position of lignin was also etherified, leading the formation of a structure of Ph-CH=CHCH2O(CH2)4OH. Interestingly, structure protection facilitated the formation of lignin nanoparticles via self-assembly (<100 nm). In addition, it was observed from pyrolysis results that addition of 1, 4-butanediol remarkably protected the structure of lignin by avoiding condensation, promoting the production of aromatics. The cellulose-rich fraction possessed a high cellulose digestibility of 91.64 % by enzymatic hydrolysis at a cellulase dosage of 15 FPU/g cellulose, approximately 6-fold untreated poplar (15.91 %). This low-temperature lignin-first strategy was of great importance for multi-products biorefining lignocellulose because it leads to the production of both lignin with super high content of β-O-4 linkages for depolymerization and highly digestible cellulose for sugar production.

Holistic lignocellulosic biorefinery approach for dual production of bioethanol and xylonic acid coupled with efficient dye removal

The complete valorization of lignocellulosic biomass (LCB) to valuable bio-products with one-step fractionation is still challenging. This study represents sustainable waste-free biorefinery routes for efficient fractionation of LCB, employing a novel pretreatment method using hydrotropic p–toluenesulfonic acid (TsOH) mixed with pentanol. The potential of LCB pretreatment using TsOH/pentanol reagent as lignin absorbent with co-production of bioethanol and xylonic acid was investigated. Biomass pretreatment at 120 °C for 40 min with 20% TsOH dosage was the optimal condition that significantly dissolved more than 88.2% of lignin and 95.1% of hemicellulose in the biphasic phase, while 95.6% of cellulose was retained in the solid phase. Further fermentation of cellulose-rich fraction using Saccharomyces cerevisiae resulted in 225 g kg−1 bioethanol yield. In addition, xylose-rich phase was converted into xylonic acid by Gluconobacter oxydans fermentation with a yield of 202 g kg−1. Importantly, the isolated lignin was altered by acid groups during sulphonation through TsOH/pentanol pretreatment, which makes lignin a potential adsorbent for cationic contaminants in wastewater. In particular, the isolated lignin achieved high adsorption capacity (300 mg/g) of methylene blue. The proposed biorefinery routes showed a high net positive energy of 3.65 MJ kg−1 dry biomass with an energy ratio of 1.70. Therefore, this study provides an innovative synergistic pretreatment using TsOH/pentanol as a promising fractionation process for efficient cascade valorization of LCB into valuable bio-products.

The coupling effects between acid-catalyzed hydrothermal pretreatment and acidic/alkaline deep eutectic solvent extraction for wheat straw fractionation

Mild hydrothermal pretreatment (HP) integrating with solvent extraction is a promising two-step technique to enhance the overall lignin and carbohydrate output for lignocellulose fractionation. This work comparatively assessed the coupling effect between mild HP (the first step) and the emerging acidic choline chloride-natural acid or alkaline choline hydroxide based deep eutectic solvents (DES, the second step) for wheat straw fractionation. It was shown HP with 0.3% p-toluenesulfonic acid (p-TsOH) catalyst achieved a good compromise between complete hemicellulose removal (nearly 100%) and high cellulose recovery (99.2%). While choline hydroxide based DES showed better coupling effect with HP than choline chloride-natural acid DES, corresponding to 75.6 and 31.2% lignin removal respectively. It was proposed that the alkaline DES enhanced lignocellulose swelling the lignin phenolic hydroxyl groups deprotonation and thus facilitating lignin solubilization despite of its condensation at HP. Therefore, the alkaline DES resulting cellulose-rich fraction exhibited higher potential for further processing.

Optimization of microfibrillated cellulose isolation from cocoa pod husk via mild oxalic acid hydrolysis: A response surface methodology approach

Theobroma cacao L. species, cultivated worldwide for its valuable beans, generates up to 72% weight of the fruit as waste. The lack of reutilization technologies in the cocoa agroindustry has hindered the exploitation of valuable bio-components applicable to the generation of high value added bioproducts. One such bioproduct is microfibrillated cellulose (MFC), a biopolymer that stands out for its desirable mechanical properties and biocompatibility in biomedical, packing, 3D printing, and construction applications. In this study, we isolated microfibrillated cellulose (MFC) from cocoa pod husk (CPH) via oxalic acid hydrolysis combined with a steam explosion. MFC isolation started with the Solid/Liquid extraction via Soxhlet, followed by mild citric acid hydrolysis, diluted alkaline hydrolysis, and bleaching pre-treatments. A Response Surface Methodology (RSM) was used to optimize the hydrolysis reaction at levels between 110 and 125 °C, 30–90 min at 5–10% (w/v) oxalic acid concentration. The cellulose-rich fraction was characterized by Fourier-Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) analyses. Characterization analyses revealed a cellulose-rich polymer with fibers ranging from 6 to 10 μm, a maximum thermal degradation temperature of 350 °C, and a crystallinity index of 63.4% (peak height method) and 29.0% (amorphous subtraction method). The optimized hydrolysis conditions were 125 °C, 30 min, at 5% w/v oxalic acid: with a 75.7% yield. These results compare with MFC obtained through highly concentrated inorganic acid hydrolysis from different biomass sources. Thus, we show a reliable and greener alternative chemical treatment for the obtention of MFC.

Highly efficient metal-acid synergetic catalytic fractionation of lignocellulose under mild conditions over lignin-coordinated N-anchoring Co single-atom catalyst

Lignin reductive depolymerization via a lignin-first strategy is extremely attractive but practically challenging due to the harsh reaction conditions, such as high temperature and high external H2 pressure. Herein, we demonstrate a highly efficient acid-assisted reductive fractionation of lignocellulose over a cobalt monatomic catalyst (Co SAs-N@LC) under mild temperature without H2. The Co SAs-N@LC with a Co-N4 conformation was fabricated by pyrolyzing phenolic-OH rich lignin-metal complex mixed with melamine. When subjected to poplar reductive fractionation at 160 °C with 0.1% H2SO4, the Co SAs-N@LC achieved a high monophenol yield of 41.7% with near complete delignification (99.7%), which was credited to the acid-metal synergy on effective lignin depolymerization, more importantly on condensation inhibition. Furthermore, thanks to the acid-catalyzed hydrolysis, xylan was simultaneously liberated, leaving a cellulose-rich fraction as the solid fraction. DFT calculations revealed that the Co-N4 conformation endowed the catalyst superior hydrogen evolution capacity and the monatomic catalyst showed satisfactory recycling stability due to the acid-resistant N-anchoring and the minimized catalyst fouling. Therefore, this work provides an effective approach for reductive fractionation of lignocellulose under mild conditions, more importantly a total biomass fractionation, through the combined use of atomically dispersed Co catalyst and acid co-catalyst.

Isolation of Pure Lignin and Highly Digestible Cellulose from Defatted and Steam-Exploded Cynara cardunculus.

In this work, a three-step approach to isolate the main components of lignocellulosic cardoon, lignin and cellulose, was investigated. The raw defatted biomass, Cynara cardunculus, after steam explosion was subjected to a mild organosolv treatment to extract soluble lignin (L1). Then, enzymatic hydrolysis was performed to achieve decomposition of the saccharidic portion into monosaccharides and isolate residual lignin (L2). The fractionation conditions were optimized to obtain a lignin as less degraded as possible and to maximize the yield of enzymatic hydrolysis. Furthermore, the effect of the use of aqueous ammonia as an extraction catalyst on both fractions was studied. Each fraction was characterized by advanced techniques, such as elemental analysis and 31P nuclear magnetic resonance (NMR), 13C-1H two-dimensional (2D)-NMR, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and UV-vis spectroscopies for lignin and X-ray diffraction (XRD), Klason compositional analysis, elemental analysis, and ATR-FTIR spectroscopy for cellulose-rich fractions. The impact of the cellulose-rich fraction composition and crystallinity was also correlated to the efficiency of the hydrolysis step, performed using the enzymatic complex Cellic CTec3.

Highly selective catalytic conversion of raw sugar and sugarcane bagasse to lactic acid over YbCl3, ErCl3, and CeCl3 Lewis acid catalysts without alkaline in a hot-compressed water reaction system

To improve the process efficiency for lactic acid production, catalytic conversion of raw cane sugar and sugarcane bagasse (SCB) to lactic acid under subcritical water condition over Lanthanide catalysts was investigated. The effect of different types of Lanthanide (III) ion catalyst namely YbCl3, ErCl3, and CeCl3 on enhancement of lactic acid (LA) yield, selectivity, turnover number [TON] and turnover frequency [TOF] was studied in the aqueous solution. The results were compared with conventional catalytic reaction for lactic acid production in strongly alkaline solution. For raw sugar-to-lactic acid conversion, ErCl3 catalyst exhibited greatest performance at 240 °C for 15 min and achieve the highest TOF and TON with 91.8% LA yield (91.79%theoretical yield) and 90.5% selectivity. In case of SCB conversion, aqueous ammonia solution (LHWAA) was the best pretreatment to eliminate lignin and hemicellulose and attain cellulose-rich fraction. The LHWAA pretreated SCB conversion to lactic acid over YbCl3 at 240 °C for 15 min achieved supreme performance for highest TOF and TON and accomplished 98.7% LA yield (88.81% theoretical yield) and 94.2% selectivity with trace amount of formic acid, acetic acid and levulinic acid as side products. The findings provided crucial information for a combined cellulose hydrolysis step with catalytic conversion of mono- and polysaccharides to lactic acid in a very shorter time relative to conventional catalytic process and biotechnological fermentation process. Lanthanide catalysts, especially ErCl3 and YbCl3, were found as promising alternative environmentally friendly catalysts providing a potential cost-efficient process of lactic acid from bioresources in a larger scale production.

An Innovative, Green Cascade Protocol for Grape Stalk Valorization with Process Intensification Technologies

Valorization of agri-food residues to produce bio-based platform chemicals will enhance the transition to the bio-economy era. To this end, a sustainable process has been developed for the overall valorization of grape stalks (GS) according to a circular approach, starting from the lignin fraction to further deal with the cellulose-rich residue. This non-conventional protocol fully adheres to green chemistry principles, exploiting the so-called enabling technologies—mainly ultrasound and microwaves—for energy-saving innovative processes. Firstly, ultrasound-assisted extraction (UAE, 40 kHz, 200 W) demonstrated to be an excellent technique for GS delignification combined with natural deep eutectic solvents (NaDESs). Delignification enables isolation of the pertinent lignin framework and the potential to obtain a polyphenol-rich liquid fraction, focusing on the valorization of GS as source of bioactive compounds (BACs). Among the NaDESs employed, the combination of choline chloride (ChCl) and levulinic acid (LevA) (ChLevA) presented noteworthy results, enabling a delignification higher than 70%. LevA is one of the top-value biobased platform chemicals. In this work, a flash microwave (MW)-assisted process was subsequently applied to the cellulose-rich fraction remained after delignification, yielding 85% LevA. The regeneration of this starting compound to produce ChLevA can lead to a further biomass delignification cycle, thus developing a new cascade protocol for a full valorization of GS.

Fractionation of carbohydrate polymers from Indonesian sorghum by-products

Extraction of cellulose and hemicellulose from natural resources has attracted considerable interest. In comparison to other cereals, there is relatively little knowledge on the cellulose, hemicellulose and lignin content of sorghum by-products. As such, the aims of this study were to develop a multi-step process for sorghum by-products (bran, stalk and panicles) fractionation and characterise them with regards to their physicochemical properties. In terms of chemical composition, sorghum panicles were found similar to bran, featuring a significant presence of arabinoxylans as well. A sequential alkaline extraction with varying concentrations of NaOH was applied, resulting in the generation of three fractions (residue, hemicellulose and alkali soluble lignin). Fractionation of sorghum stalks with 1.0 M NaOH at 50 °C for 3 h obtained ~64 % (w/w) cellulose rich fraction and 52 % (w/w) of xylose, predominant in the hemicellulose fraction. In the bran, the fractionation with 0.75 M NaOH at 50 °C for 3 h obtained ~40 % (w/w) cellulose rich fraction. Approximately 76 % of the glucose was in hemicellulose fraction reflecting starch solubilisation in the case of bran, while nearly 2 % (w/w) alkaline-soluble lignin was extracted. Overall, this study demonstrated an effective approach for the fractionation and the recovery of key components in sorghum by-products.

Lignocellulosic biomass fractionation with the use of deep natural eutectic solvents

Brazil has a privileged position as a leader in the integral use of vegetable biomass because it has the largest biodiversity on the planet. Adding value to a refinery is associated with the treatment and disaggregation of the biomass components. There are processes applied to biomass fractionation to remove or break the layers of lignin and hemicellulose, which allows enzymes to access cellulose more easily. In view of this a great diversity of technological routes can be used, and alternative techniques that have been developed such as the use of the natural deep eutectic solvent (NADES). Thus, the objective of the present work was to perform the fractionation of the bark biomass from E. urograndis species into two fractions: cellulose rich fraction (CRF) and lignin rich fraction (LRF) using NADES. In this process three conditions were applied for biomass fractionation: conventional heating at 100ºC, microwave radiation with power of 600W and 1000 W, and room temperature at 25ºC. The percentages obtained through conventional heating were 72,25% of CRF, 27,75% of LRF; 72,54% of CRF with microwave radiation at a power of 1000W, 27,46% of LRF. The techniques used for characterization of CRF were: Fourier transformed infrared (FTIR) spectroscopy and X-ray diffractometry (XRD) for crystallinity analysis and scanning electron microscopy (SEM). For characterization of LRF the techniques were used: UV-vis and FTIR spectroscopy. The use of NADES a low cost, sustainable organic solvent combined with microwave radiation proved to be efficient for biomass fractionation.

Bioethanol and succinic acid co-production from imidazole-pretreated soybean hulls

The soybean is an important crop in the world, where soybean hull (SH) comprehends 8–10 % of grain dry matter. SH is rich in carbohydrates, mainly in holocellulose fibers, showing to be a promising bio-based material to generate new bio-products. Imidazole is a promissing solvent for pretreatment of lignocellulosic biomass due its delignificant and depolymerizing power. Besides, this reagent presents low to moderate toxicity against many classes of living organisms. Thus, the thermochemical conversion of SH into fermentable sugars using imidazole was carried out at 120 °C for 1 h. The objective of this work was to use a more sustainable pretreatment reagent for the co-production of second-generation bioethanol and succinic acid from soybean hull. After pretreatment, the solid yield was 57.1 wt.%, consisting principally of cellulose. The cellulose-rich fraction was further hydrolyzed using commercial enzymes and achieving 89.9 wt.% and 95.6 wt.% of glucose and xylose yields, respectively. The hydrolysate was fermented using two yeasts: Saccharomyces cerevisiae and Pichia stipitis. Approximately, from 1 ton of SH, it was estimated that 124.0 kg of bioethanol and 36.5 kg of succinic acid could be obtained using S. cerevisiae, while P. stipitis could achieve productions of 116.2 kg of bioethanol and 20.4 kg of the organic acid. This study demonstrated the co-production of biomolecules of industrial interests, carrying out a more environmentally friendly pretreatment process.

Complete conversion of lignocellulosic biomass into three high-value nanomaterials through a versatile integrated technical platform

An integrated technique of hydrothermal pretreatment coupling with deep eutectic solvent (DES) extraction was tailed to cleanly fractionate lignocellulose into three usable forms, i.e., water-soluble hemicellulose, cellulose-rich and lignin fractions, which were further upgraded to three nanomaterials, i.e., activated nanocarbons (ANCs), lignin-containing cellulose nanofibers (LCNFs), lignin nanospheres (LNSs) respectively. Almost 100% hemicellulose was solubilized in the hydrothermal pretreatment, which was used as carbon source to produce ANCs with rather high specific surface area (about 2680 m2 g−1) through in situ carbonation followed by activation. Cellulose-rich fraction was used to produce LCNFs with high aspect ratio (about 150) using facile mechanical refining. While the clean lignin fraction with enhanced amphiphilic properties was used to produce LNSs (223 nm diameter) using self-assembly method. The related mechanism was that condensed lignin could still be extracted by DES due to its excellent lignin solubility. The resulting lignin amphiphilicity provided a powerful driving force to enhance the self-assembly process thus compact LNSs was obtained. Meanwhile, the DES-swelled cellulose structure significantly facilitated the subsequent mechanical disintegration for LCNFs production. In this work, the proposed integrated technique platform realized the complete utilization concept of lignocellulosic biomass, and also provided three high-value nanomaterials product streams for downstream application towards an industrial relevant process.

Influence of different household Food Wastes Fractions on Volatile Fatty Acids production by anaerobic fermentation

This research investigated for the first time the influence of the single fractions (proteins, lipids, starch, cellulose, fibers and sugars) composing Household Food Wastes on Volatile Fatty Acids (VFA). A production at different pH (uncontrolled, 5.5 and 7.0): both the amount and profile of VFA were investigated. It was found that fractions rich in proteins and starch led to the greatest VFA productions (12–15 g/L), especially at neutral pH condition. On the contrary, fractions rich in cellulose, fibers, and sugars showed a very low VFA production (<2 g/L). The chemical nature of HFW influenced the speciation of the microbial communities too. Lactobacillaceae family was highly represented in proteins-, starch-, fibers and sugars-rich substrates and Atopobiaceae, Eggerthellaceae, Acidaminococcaceae and Veillonellaceae displayed positive correlation to VFAs production. Instead, Comamonadaceae showed high relative abundance in lipids- and cellulose-rich fraction and was negatively correlated to the VFAs generation.

External fields enhanced glycerol pretreatment of forestry waste for producing value-added pyrolytic chemicals

Softwood forestry waste is an abundantly available lignocellulosic feedstock which could be converted into value-added chemicals via fast pyrolysis. However, its prominent recalcitrant nature resulting from the tightly intertwining of cellulose, hemicellulose and lignin as well as the catalytic effect of alkaline and alkaline earth metals (AAEMs) in it make the valorization of target pyrolytic chemicals particularly challenging. Glycerol pretreatment is a novel process to disrupt the recalcitrant structure of lignocellulose by separating it into three fractions. However, pretreatment effect from conventional heating assisted glycerolysis is poor due to low heat transfer. Introduction of external fields such as ultrasonic and microwave radiation could effectively improve the pretreatment effect. Microwave heating enabled better pretreatment effect than conventional oil bath heating due to its rapid heat transfer and athermal effect. Turbulence effects of ultrasonic radiation enhanced uniformly mixing of feedstock with glycerol, therefore further improving the pretreatment effect. The optimal glycerol pretreatment effect was realized by ultrasonic radiation integrated with microwave heating process, with pine sawdust deconstructed into 53.09 wt.% cellulose-rich fraction, 14.64 wt.% hemicellulose-derived sugars and 12.46 wt.% organosolv lignin, simultaneously removing 91.7 wt.% AAEMs. This considerably facilitated the formation of target pyrolytic chemical (levoglucosan), whilst preventing the production of undesired low molecular weight oxygenates such as acids, ketones, aldehydes. The highest yield of levoglucosan reached up to 52.07 wt.%. Kinetic analysis revealed that, higher activation energy is required for the glycosidic cleavage-based concerted reactions of cellulose into levoglucosan than AAEM catalyzed ring-breaking into light oxygenates. This work introduces an efficient method to produce value-added chemicals from forestry waste whilst reducing its hazardous impact on environment.

Lignin Extraction from Waste Pine Sawdust Using a Biomass Derived Binary Solvent System.

Lignocellulosic biomass fractionation is typically performed using methods that are somehow harsh to the environment, such as in the case of kraft pulping. In recent years, the development of new sustainable and environmentally friendly alternatives has grown significantly. Among the developed systems, bio-based solvents emerge as promising alternatives for biomass processing. Therefore, in the present work, the bio-based and renewable chemicals, levulinic acid (LA) and formic acid (FA), were combined to fractionate lignocellulosic waste (i.e., maritime pine sawdust) and isolate lignin. Different parameters, such as LA:FA ratio, temperature, and extraction time, were optimized to boost the yield and purity of extracted lignin. The LA:FA ratio was found to be crucial regarding the superior lignin extraction from the waste biomass. Moreover, the increase in temperature and extraction time enhances the amount of extracted residue but compromises the lignin purity and reduces its molecular weight. The electron microscopy images revealed that biomass samples suffer significant structural and morphological changes, which further suggests the suitability of the newly developed bio-fractionation process. The same was concluded by the FTIR analysis, in which no remaining lignin was detected in the cellulose-rich fraction. Overall, the novel combination of bio-sourced FA and LA has shown to be a very promising system for lignin extraction with high purity from biomass waste, thus contributing to extend the opportunities of lignin manipulation and valorization into novel added-value biomaterials.

Toward waste valorization by converting bioethanol production residues into nanoparticles and nanocomposite films

A “waste-valorization” approach was developed to transform recalcitrant hydrolysis lignin (HL) from second-generation bioethanol production into multifunctional bio-based products. The hydrolysis lignin (HL) was extracted with aqueous acetone, yielding two fractions enriched in lignin and cellulose, respectively. The soluble hydrolysis lignin (SHL) was converted into anionic and cationic colloidal lignin particles (CLPs and c-CLPs). The insoluble cellulose-rich fraction was transformed into lignocellulosic nanofibrils that were further combined with CLPs or c-CLPs to obtain nanocomposite films with tailored mechanical properties, oxygen permeability and antioxidant properties. To enable prospective applications of lignin in nanocomposite films and beyond, CLPs and c-CLPs were also produced from a soda lignin (SL) and the influence of the lignin type on the particle size and ecotoxicity was evaluated. Finally, the carbon footprint of the entire process from hydrolysis lignin to films was assessed and an integration to industrial scale was considered to reduce the energy consumption. While most previous work utilizes purified lignin and pristine and often purified cellulose fibers to produce nanomaterials, this work provides a proof of concept for utilizing the recalcitrant lignin-rich side stream of the bioethanol process as raw material for functional nanomaterials and renewable composites.

Pine Cone Biorefinery: Integral Valorization of Residual Biomass into Lignocellulose Nanofibrils (LCNF)-Reinforced Composites for Packaging

Presented herein is the integral valorization of residual biomass to film composites by their fractionation into building blocks in a multicomponent cascade isolation approach. First, pine cones were subjected to alkaline pretreatment, followed by soda pulping. Two different hemicellulose/lignin-based fractions were recovered from the extractives of these treatments, with a yield of 19%. Then, chloride- and peroxide-based bleaching methods were proposed to treat the soda-pulped samples, obtaining two cellulose-rich fractions with different chemical compositions and recovery yields (32% and 44%, respectively). From these cellulose fractions, two types of nanocelluloses with different lignin contents were obtained: cellulose nanofibrils (CNF), with a lignin content of 1%, and lignocellulose nanofibrils (LCNF), with a lignin content of 16%. The LCNF displayed lower crystallinity and viscosity but greater diameter and thermal stability than the CNF. The reinforcing capability of different amounts of both nanocelluloses on the first hemicellulose/lignin-based fraction (PCA-L) to form films was evaluated. The thermomechanical, barrier, antioxidant, moisture sorption, and mechanical properties were assessed and compared. In general, the LCNF films showed less moisture sorption and better thermomechanical and antioxidant properties than the CNF films. These results reveal LCNF to be a promising reinforcing agent for designing all-lignocellulose-based composite films to be used in food packaging applications.

Lipid bioproduction from delignified native grass (Cyperus distans) hydrolysate by Yarrowia lipolytica

In the present study, native grass (Cyperus distans) was utilized for the production of lipid using Yarrowia lipolytica MTCC 9519. Initially, pretreatment methods using hydrothermal and alkaline delignification were performed to obtain cellulose rich liquid fractions. Delignified native grass biomass was enzymatically hydrolyzed to convert non fermentable sugars in to fermentable sugars. The growth of Y. lipolytica MTCC 9519 by utilizing pretreated native grass hydrolysate was evaluated. The yield and concentration of total reducing sugars after enzyme hydrolysis were found to be 378 ± 35 mg/g of pretreated biomass and 28.64 g/L ± 1.25 g/L, respectively. When pretreated, delignified native grass hydrolysate was used with (NH4)2SO4 (30C/N ratio) and sodium n-octanoate (0.4% w/w), the dry cell weight and lipid accumulation of Y. lipolytica MTCC 9519 reached about 19.88 ± 1.54 g/L and 53.62% (w/w) respectively after 96 h. Thus, native grass could become a promising substrate for biolipid production.

Production of edible fungal (Rhizopus delemar CBS 145940) biomass from organosolv-pretreated oil palm empty fruit bunch (OPEFB) in submerged fermentation

Accumulation of oil palm empty fruit bunches (OPEFB) from palm oil industry poses challenges for the disposal process, which leads to environmental damage. For this reason, valorization of OPEFB fractions to produce edible fungal biomass was carried out in this research. The fungus was Rhizopus delemar CBS 145940, which is an edible fungus, Indonesian indigenous, and is favorable for the production of several end products. Organosolv pretreatment was first conducted on OPEFB using ethanol (50%) as the solvent. Enzymatic hydrolysis was then performed using Cellic® Ctec3 on the pretreated-OPEFB fractions. Hydrolyzates from cellulose-rich fraction, slurry (a mixture of cellulose-rich fraction and hemicellulose-rich fraction), and hemicellulose-rich fraction were used as the cultivation media for fungal growth. The corresponding yield of fungal biomass from each medium was 0.62 ± 0.07 g/g glucose; 0.41 ± 0.02; and 0.61 ± 0.13 g/g fermentable sugars, respectively. These results showed that Rhizopus delemar CBS 145940 could be grown in all the hydrolyzates from the OPEFB fractions. Nevertheless, in order to obtain higher fungal biomass, supplementation of nutrition was needed.