Integrated NIRS and QTL assays reveal minor mannose and galactose as contrast lignocellulose factors for biomass enzymatic saccharification in rice

Background: Identifying lignocellulose recalcitrant factors and exploring their genetic properties are essential for enhanced biomass enzymatic saccharification in bioenergy crops. Despite genetic modification of major wall polymers has been implemented for reduced recalcitrance in engineered plant, it could most cause a penalty of plant growth and biomass yield. Alternatively, it is increasingly considered to improve minor wall components, but an applicable approach is required for efficient assay of large population of biomass samples. Hence, this study collected total 100 rice straw samples and characterized all minor wall monosaccharides and biomass enzymatic saccharification by integrating NIRS modeling and QTL profiling. Results: By performing classic chemical analyses and establishing optimal NIRS equations, this study examined a diversity of four minor wall monosaccharides and major wall polymers (acid-soluble lignin/ASL, acid-insoluble lignin/AIL, three lignin monomers, crystalline cellulose), which led to largely varied hexoses yields achieved from enzymatic hydrolyses after two alkali pretreatments were conducted with all rice straws. Correlation analyses indicated that mannose and galactose could play a contrast role for biomass enzymatic saccharification at P < 0.0l level (n=100). Meanwhile, this study found that QTLs controlling mannose, galactose, lignin-related traits and biomass saccharification were co-located. Notably, by combining NIRS assay with QTLs maps, this study interpreted that the mannose-rich hemicellulose may assist AIL disassociation for enhanced biomass enzymatic saccharification, whereas the galactose-rich polysaccharides should be effectively extracted with ASL from alkali pretreatment for condensed AIL association with cellulose microfibrils against enzymatic hydrolysis. Conclusions: By integrating NIRS assay with QTL profiling for large population of rice straw samples, this study identified that the mannose of wall polysaccharides could positively affect biomass enzymatic saccharification, whereas the galactose had a significantly negative impact. It also sorted out that two minor monosaccharides should distinctively associate with lignin deposition for wall network construction. Hence, this study has demonstrated an applicable approach for fast assessments of minor lignocellulose recalcitrant factors and biomass enzymatic saccharification in rice, and it has also provided a potential strategy for bioenergy crop breeding.

Assessment of rotary drum and aerated in-vessel for composting of garden waste

For in-vessel composting of garden waste, the selection of reactor is an important factor for efficient degradation. The present study evaluates working performance of rotary drum reactor (RDR) and aerated in-vessel (AIV) for composting of garden waste. 100 kg garden waste was mixed with 10 kg cow-dung slurry and 5 kg compost and feed into both the reactors for 45 days composting period. The reactors vary in their system configuration, shape and orientation, blade design, rate of aeration, odour control, leachate production and energy requirements. Rotary drum was rotated daily six times in clockwise and anti-clockwise direction and AIV was rotated daily for 3–5 minutes using motor. Rise in temperature started within 24 hours of composting and reached 65°C and 59°C on second day itself and thermophilic phase continued for 7 and 5 days for RDR and AIV respectively. Moisture content reduction after composting period was 15.25 and 18.45 %, C/N ratio was 16.14 and 13.33, TVS reduction was 23.74 and 29.78 % and CO2 evolution rate was 6.18 and 4.14 mg/g VS/day in RDR and AIV respectively. Reduction of hemicellulose, cellulose, and lignin was more in AIV. The percentage reduction of acid insoluble lignin was 36.10 and 29.01 % and the percentage reduction of acid soluble lignin was 48.85 and 43.3% in in AIV and RDR respectively after 45 days. AIV gave better performance for composting of garden waste.

Multi-step purification method of water-soluble oligosaccharides produced from hardwood and softwood

Pressurized hot water pretreatment was performed on softwood (SW) and hardwood (HW) chips following the same conditions (1 h at 170 °C) in order to partly hydrolyse hemicelluloses. The complete characterization of these sugar enriched autohydrolysates (AH) being rather complex, two different purification methods were conducted. Nanofiltration (NF) 1kDa membrane and ultrafiltration (UF) 3 and 5kDa membranes were used to separate oligosaccharides (OS) from undesired compounds and for their molar mass fractionation. Granulated activated charcoal (GAC) adsorption was also used for hydrolysates detoxification. The chemical nature of OS and side charge groups vary significantly depending of the fractions obtained, e. g. xylans' chain length is positively correlated with the degree of acetylation. UF at 5kDa allows for the total separation of galactoglucomannans (GGMs) from xylans, in SW AH, however, this result was not achieved with HW. From the acid soluble lignin (ASL) removal point of view, membrane filtration from 1kDa is more efficient than activated carbon treatment concerning HW AH, on the contrary to SW AH. Regarding the lignin to OS ratio, for both species, GAC leads to a better sugar purity.

Investigation of eucalypt and pine wood acid-soluble lignin by Py-GC-MS

The Klason method is adequate for quantifying lignin in softwood (SWD) but is less so for hardwood (HWD). The latter contains a fraction of acid-soluble lignin (ASL) that is not measurable under the conditions prevailing in the Klason method and that must be quantified by other means. This study aimed at investigating the composition of ASL obtained from eucalypt and pine woods by using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). About 2.7% and 0.9% ASL by dry wood weight were measured in the acid filtrate of eucalypt and pine, respectively, by the Technical Association of the Pulp and Paper Industry (TAPPI) UM 250 method. The acid filtrate was lyophilized and processed by Py-GC-MS, allowing identification of 26 primary pyrolysis products, with 2% and 52% relative molar abundance coming from lignin and carbohydrates, respectively, for eucalypt and 24 primary pyrolysis products, with 1% and 54% relative molar abundance from lignin and carbohydrates, respectively, for pine. The main products derived from lignin were phenol, 4-methylphenol, guaiacol, 4-methylcatechol, syringol, acetosyringone and vanillin. It was concluded that measurements of ASL remain a requirement for accurate eucalypt and pine wood lignin quantification because lignin derivatives remain in the acid filtrate from the Klason lignin quantification method. Corrections for carbohydrate-derived compounds are not necessary, despite their predominance in the filtrate, because these derivatives do not interfere with ultraviolet (UV) absorption.

Short Communication: Variation in chemical constituent of Styrax sumatrana wood growing at different cultivation site in North Sumatra, Indonesia

Iswanto AH, Siregar YS, Susilowati A, Darwis A, Hartono R, Wirjosentono B, Rachmat HH, Hidayat A, Fatriasari W. 2019. Variation in chemical constituent of Styrax sumatrana wood growing at different cultivation site in North Sumatra, Indonesia. Biodiversitas 20: 448-452. Kemenyan Toba (Styrax sumatrana) is known as endemic resin-producing trees that naturally grow in North Sumatra and distributed throughout five districts within the province. Different growing site may constitute to different characteristics of the species, e.g. morphological differences, chemical constituent, bioactive substances, etc. Different characteristics of wood chemical constituent are an important factor determining further utilization and potential use of wood in wider spectrums. Information about wood chemical constituent of Styrax sumatrana growing from different site has not been determined yet. Therefore, the objective of this research was to analyze the characteristics of chemical constituent of Styrax sumatrana wood originated from North Tapanuli and Pakpak Bharat according to axial direction of stem (bottom, middle, and top). Chemical properties such as hollocelulose, α-cellulose, hemicellulose, Acid Soluble Lignin (ASL), acid insoluble lignin (AIL), and non-structural component (extractive content in ethanol benzene 1: 2 and ash content) were observed. Results showed that different growth location would yield in different wood chemical constituent. The wood chemical constituent from North Tapanuli and Pakpak Bharat were 52.72 and 69.80% (hollocelulose), 25.94 and 39.87% (α-cellulose), 26.78 and 29.92% (hemicellulose), 5.49 and 4.33% (Acid Soluble Lignin), 4.37 and 20.43% (Acid-Insoluble Lignin), 10.95 and 2.42% (extractive content), 1.37 and 0.8% for ash content.

Determination of Organic Fractions and Enzymatic Activity in Forest Spruce Soil of Tatra National Park

The formation and quality of soil organic matter (SOM) highly depends on the input of organic material and microbial enzymatic activities. Soil extractions with specific nonpolar and polar extractives can be used to identify qualitative changes in SOM. The aim of this paper was to understand the correlations among microbial enzymatic activity and specific organic fractions in acidic spruce forest soil. Klason lignin (KL), acid soluble lignin (ASL), holocellulose (HC), SOM content, and potential enzymatic activity (FDA and phosphatase) was measured and analyzed. We sampled Dystric Cambisol of forest spruce stands (Picea abies) in Tatra National Park (Slovakia). The SOM fractions were determined gravimetrically based on their extractivity in nonpolar (dichloromethane (DME)) and polar (acetone (AE), ethanol (EE), water (WE)) solvents Total extractives content was 0.079% and nonpolar extractives 0.036%. The mean amount of polar extractives tented to increase in the order EE<AE<WE. The total lignin content was determined to be 1.079% and HC 0.774%. FDA negatively correlated with KL (r=-0.873 p<0.05) and DME (r=-0.913 p<0.05). Phosphatase positively correlated with WE (r=0.972 p<0.01) and KL (r=0.957 p<0.01).

Fermentable Sugar Production from the Peels of Two Durian (Durio zibethinus Murr.) Cultivars by Phosphoric Acid Pretreatment

The potential of durian (Durio zibethinus Murr.) peel as feedstock for the production of fermentable sugars was evaluated. Durian peel biomass from two cultivars, monthong (Durio zibethinus Murr. cv. Monthong) and chanee (Durio zibethinus Murr. cv. Chanee), were pretreated with different concentrations (70%, 75%, 80%, and 85%) of phosphoric acid (H3PO4) at a moderate temperature of 60 °C for 60 min. The H3PO4-pretreated durian peel biomass was then subjected to enzymatic hydrolysis. Significantly higher glucan (44.74 ± 0.21%) content was observed in the monthong peel compared to the chanee peel (42.06 ± 0.28%). Phosphoric acid pretreatment caused the significant solubilization of the xylan and acid soluble lignin (ASL) contents. This enhanced the enzymatic hydrolysis process causing a significant increase in the hydrolysis efficiency and glucose concentration. The highest hydrolysis efficiency and glucose concentration were obtained after 72 h from the 75% H3PO4-pretreated peel biomass for both the monthong (90.33 ± 0.42% and 9.55 ± 0.11 g/L, respectively) and chanee (90.06 ± 0.40% and 8.56 ± 0.13 g/L, respectively) peels. Biomass to glucose recovery for monthong and chanee were improved by approximately 7- and 6-fold, respectively. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis showed destruction of the peel biomass structure and changes in the cellulose crystallinity index (CrIs).

Equilibrium, kinetic and thermodynamic studies of acid soluble lignin adsorption from rice straw hydrolysate by a self-synthesized macro/mesoporous resin

A self-synthesized HQ-8 resin was prepared using a O/W suspension polymerization technique and employed as a potential adsorbent for the removal of acid soluble lignin (ASL) from rice straw hydrolysate (RSH).