Whole sugar 2,3-butanediol fermentation for oil palm empty fruit bunches biorefinery by a newly isolated Klebsiella pneumoniae PM2

Effective utilization of cellulose and hemicelluloses is essential to sustainable bioconversion of lignocellulose. A newly isolated xylose-utilizing strain, Klebsiella pneumoniae PM2, was introduced to convert the biomass "whole sugars" into high value 2,3-butanediol (2,3-BDO) in a biorefinery process. The fermentation conditions were optimized (30°C, pH 7, and 150 rpm agitation) using glucose for maximum 2,3-BDO production in batch systems. A sulfite pretreated oil palm empty fruit bunches (EFB) whole slurry (substrate hydrolysate 119.5 g/L total glucose mixed with pretreatment spent liquor 80 g/L xylose) was fed to strain PM2 for fermentation. The optimized biorefinery process resulted in 75.03 ± 3.17 g/L of 2,3-BDO with 0.78 ± 0.33 g/L/h productivity and 0.43 g/g yield (87% of theoretical value) via a modified staged separate hydrolysis and fermentation process. This result is equivalent to approximately 135 kg 2,3-BDO and 14.5 kg acetoin precursors from 1 ton of EFB biomass without any wastage of both C₆ and C₅ sugars.

Influence of wet oxidation pretreatment with hydrogen peroxide and addition of clarified manure on anaerobic digestion of oil palm empty fruit bunches

Food and energy requirements are increasing globally, and the challenge is to meet these demands in a sustainable manner. Oil palm has a relatively high productivity, but produces the lignocellulosic residue of empty fruit bunches (OPEFB). In this study, wet oxidation pretreatment is utilized to overcome the recalcitrance of OPEFB during semi-continuous anaerobic digestion (AD) with between 19.7 and 52.7% improvement over the control, and near total cellulose and hemicellulose content could be degraded. Clarified manure, the water phase of cattle and dairy manure after filtration, is further tested for its effect on methane production by providing necessary micronutrients and vitamins. An increase of 49% was found after addition of clarified manure to OPEFB compared to without this addition.

Pentose-rich hydrolysate from oil palm empty fruit bunches for β-glucan production using Pichia jadinii and Cyberlindnera jadinii

Pentose-rich hydrolysate obtained from dilute acid pretreatment of oil palm empty fruit bunches was successfully consumed by pentose-consuming yeasts: Cyberlindnera jadinii (Cj) and Pichia jadinii (Pj). Nitrogen supplementation and no additional detoxification step were required. Pj produced 5.87 g/L of biomass using a C/N ratio of 14 after 120 h of fermentation, with xylose consumption of 71%. Cj produced 10.50 g/L of biomass after 96 h of fermentation with C/N ratio of 11.5, with maximum xylose consumption of 85%. β-glucans, high value-added macromolecules, were further extracted from the yeast biomass, achieving yields of 3.1 and 3.0% from Pj and Cj, respectively. The isolated polysaccharides showed a chemical structure of β-(1,3)-glucan with residues of other molecules. Additionally, β-(1,6) branches seems to have been broken during isolation process. Further studies assessing β-glucans production at industrial scale should be carried out looking for nitrogen sources and optimizing the β-glucan isolation method.

Lignin from oil palm empty fruit bunches: Characterization, biological activities and application in green synthesis of silver nanoparticles

Lignin was extracted from oil palm empty fruit bunches under four different conditions. The lignin samples were characterized and employed in the green synthesis of silver nanoparticles. Two-dimensional HSQC NMR analysis showed that lignins extracted under more aggressive conditions (3.5% acid, 60 min) exhibited less signals and thus, presented a more degraded chemical structure. Additionally, those lignins obtained under harsh conditions (3.5% acid, 60 min) exhibited higher antioxidant capacity than those obtained under mild conditions (1.5% acid, 20 min). Formation of lignin-mediated silver nanoparticles was confirmed by color change during their synthesis. The surface plasmon resonance peaks (423-427 nm) in UV-visible spectra also confirmed the synthesis of AgNPs. AgNPs showed spherical shape, polycrystalline nature and average size between 18 and 20 nm. AgNPs, in suspension, presented a negative Zeta potential profile. Lignin was assumed to contribute in the antioxidant capacity exhibited by AgNPs. All AgNPs presented no significant differences on the disk diffusion antimicrobial susceptibility test against E. coli. The minimum inhibitory concentration of HAL3-L AgNPs (62.5 μg·mL^-1) was better than other physicochemically produced AgNPs (100 μg·mL^-1).

Preparation and characterization of nanosized lignin from oil palm (Elaeis guineensis) biomass as a novel emulsifying agent

A study was carried out to determine the effectiveness of lignin, extracted from oil palm (Elaeis guineensis) biomass as water-in-oil (W/O) emulsifying agent. To achieve this goal, soda lignin (SL) was extracted via soda pulping process and a series of nanosized soda lignin (NSL) were prepared using homogenizer at three different speed i.e. 10,400 rpm (NSL 10), 11,400 rpm (NSL 11) and 12,400 rpm (NSL 12) for one hour. All prepared samples were characterized by FT-IR, UV-Vis spectroscopy, thermogravimetric analysis (TGA), zeta potential analyser, Transmission Electron Microscope (TEM) and Extreme High Resolution Field Emission Scanning Electron Microscope (XHR-FESEM). The result of FTIR showed that there is no prominent change occurred in spectra of all samples while a good stability was reflected by TGA curves. The percentage of creaming index and visual observations of all samples demonstrated that NSL 12 and dosage 2 g (out of 1 g, 1.5 g and 2 g) were found to be the best among all samples. Furthermore, the results of IFT indicate that NSL 12 was proven to be more stable than the commercial product. Therefore, NSL 12 is selected for toxicological studies and was found safe in both, in vitro and in vivo studies.

Thermotolerant cellulolytic Clostridiaceae and Lachnospiraceae rich consortium enhanced biogas production from oil palm empty fruit bunches by solid-state anaerobic digestion

Thermotolerant cellulolytic consortium for improvement biogas production from oil palm empty fruit bunches (EFB) by prehydrolysis and bioaugmentation strategies was investigated via solid-state anaerobic digestion (SS-AD). The prehydrolysis EFB with Clostridiaceae and Lachnospiraceae rich consortium have maximum methane yield of 252 and 349 ml CH₄ g^-1 VS with total EFB degradation efficiency of 62% and 86%, respectively. Clostridiaceae and Lachnospiraceae rich consortium augmentation in biogas reactor have maximum methane yield of 217 and 85.2 ml CH₄ g^-1 VS with degradation efficiency of 42% and 16%, respectively. The best improvement of biogas production was achieved by prehydrolysis EFB with Lachnospiraceae rich consortium with maximum methane production of 113 m³ CH₄ tonne^-1 EFB. While, Clostridiaceae rich consortium was suitable for augmentation in biogas reactor with maximum methane production of 70.6 m³ CH₄ tonne^-1 EFB. Application of thermotolerant cellulolytic consortium into the SS-AD systems could enhance biogas production of 3-11 times.

An ionic liquid treatment and fractionation of cellulose, hemicellulose and lignin from oil palm empty fruit bunch

This work reports on a complete isolation and characterization of lignocellulosic compounds from oil palm empty fruit bunch (OPEFB) by ionic liquid (IL) treatment and alkaline treatment processes. The fractionated lignocellulosic compounds were confirmed by FTIR and CP/MAS ¹³CNMR analyses. The yield of the cellulose, hemicellulose and lignin fractions was 52.72±1.50% wt., 27.17±1.68% wt. and 16.82±1.15% wt. with molecular weight of 1869g/mol, 1736g/mol and 2695g/mol, and degradation temperature of 325.65°C, 236.25°C, and 201.40°C, respectively. The SEM image illustrates the bundle-like fiber of cellulose fraction and smaller particle size of hemicellulose and lignin fractions with inconsistent shape. The XRD patterns depict the crystalline cellulose, amorphous lignin and partially amorphous hemicellulose fractions property. The IL could be recovered and reused with an overall recovery of 48% wt. after the fourth cycle.

Steam explosion pretreatment of oil palm empty fruit bunches (EFB) using autocatalytic hydrolysis: A biorefinery approach

The oil palm empty fruit bunches (EFB) are an attractive source of carbon for the production of biochemical products, therefore, the aim of this work is to analyze the effect of the steam explosion (SE) pretreatment under autocatalytic conditions on EFB using a full experimental design. Temperature and reaction time were the operational variables studied. The EFB treated at 195°C for 6 min showed an increase of 34.69% in glycan (mostly cellulose), and a reduction of 68.12% in hemicelluloses, with increased enzymatic digestibility to 33% producing 4.2 g L(-1) of glucose. Scanning electron micrographs of the steam treated EFB exhibited surface erosion and an increased fiber porosity. Fourier transform infrared spectroscopy showed the solubilization of hemicellulose and modification of cellulose in treated EFB.

Lignin preparation from oil palm empty fruit bunches by sequential acid/alkaline treatment--A biorefinery approach

Lignin is an important raw material for the sustainable biorefineries and also the forerunner of high-value added products, such as biocomposite for chemical, pharmaceutical and cement industries. Oil palm empty fruit bunches (OPEFB) were used for lignin preparation by successive treatment with 1% (w/w) H2SO4 at 121°C for 60 min and 2.5% NaOH at 121°C for 80 min resulting in the high lignin yield of 28.89%, corresponding to 68.82% of the original lignin. The lignin obtained was characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The results indicated a lignin with molecular masses ramping from 4500 kDa to 12,580 kDa. FTIR and NMR of these lignins showed more syringyl and p-hydroxyphenyl than guaiacyl units. Moderate acid/alkaline treatment provided lignin with high industrial potential and acid hydrolyzates rich in fermentable sugars and highly porous cellulosic fibers.

Effect of fungal and phosphoric acid pretreatment on ethanol production from oil palm empty fruit bunches (OPEFB)

Oil palm empty fruit bunches (OPEFB), a lignocellulosic residue of palm oil industries was examined for ethanol production. Milled OPEFB exposed to simultaneous saccharification and fermentation (SSF) with enzymes and Saccharomyces cerevisiae resulted just in 14.5% ethanol yield compared to the theoretical yield. Therefore, chemical pretreatment with phosphoric acid, a biological pretreatment with white-rot fungus Pleurotus floridanus, and their combination were carried out on OPEFB prior to the SSF. Pretreatment with phosphoric acid, combination of both methods and just fungal pretreatment improved the digestibility of OPEFB by 24.0, 16.5 and 4.5 times, respectively. During the SSF, phosphoric acid pretreatment, combination of fungal and phosphoric acid pretreatment and just fungal pretreatment resulted in the highest 89.4%, 62.8% and 27.9% of the theoretical ethanol yield, respectively. However, the recovery of the OPEFB after the fungal pretreatment was 98.7%, which was higher than after phosphoric acid pretreatment (36.5%) and combined pretreatment (45.2%).