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Abstract A shift towards a sustainable and green society is vital to reduce the negative effects of climate change associated with increased CO2 emissions. Lignocellulosic biomass is both renewable and abundant, but is recalcitrant to deconstruction. Among the methods of pretreatment available, organosolv (OS) delignifies cellulose efficiently, significantly improving its digestibility by enzymes. We have assessed the hydrolysability of the cellulose-rich solid fractions from OS-pretreated spruce and birch at 2% w/v loading (dry matter). Almost complete saccharification of birch was possible with 80 mg enzyme preparation/gsolids (12 FPU/gsolids), while the saccharification yield for spruce was only 70%, even when applying 60 FPU/gsolids. As the cellulose content is enriched by OS, the yield of glucose was higher than in their steam-exploded counterparts. The hydrolysate was a transparent liquid due to the absence of phenolics and was also free from inhibitors. OS pretreatment holds potential for use in a large-scale, closed-loop biorefinery producing fuels from the cellulose fraction and platform chemicals from the hemicellulose and lignin fractions respectively.

Purpose: Sugars production from secondary resources has been recognised as a strategic process unit within the valorisation routes of waste. In this context, food waste (FW) as an abundant waste stream with elevated concentrations of glucose and carbohydrates (cellulose, starch) could stand as a suitable feedstock for saccharification. To evaluate this new potential application of FW, FW enzymatic hydrolysis was investigated via non-commercial enzymes. Methods: FW was subjected to enzymatic hydrolysis by an amylolytic and a cellulolytic formulation under different enzyme loadings. At the optimum conditions, the time course of glucose production during enzymatic hydrolysis was also studied. In order to enlighten the viability of bioethanol production process from FW, the experimental results were evaluated in terms of cost of enzymes per liter of bioethanol produced. Results: 81% starch hydrolysis was achieved after 1 h of hydrolysis by 45 μL amylolytic enzyme NS22109/g starch at 65 °C. With regard to the effect of cellulase loading, 175 μL NS22177/g cellulose achieved 50% saccharification yield. Further increase of enzyme dosage just slightly increased the yield. More specifically, by increasing the enzyme loading 540%, the resulting saccharification efficiency increased by just 16%. Last, the enzyme cost per ethanol yield was almost 3.5 times lower when just amylolytic enzymes were used for similar ethanol yields. Conclusion: Enzymatic hydrolysis of starch and cellulose present in FW proved to be technically efficient providing high yields. Nevertheless, the difference in the economic weight of the use of amylolytic and/or cellulolytic enzymes strongly influences the viability of FW valorization via bioethanol production. [ABSTRACT FROM AUTHOR]

Pinewood is an abundant source of lignocellulosic biomass that has potential to be used as renewable feedstock in biorefineries for conversion into advanced biofuels and other value-added chemicals. However, its structural recalcitrance, due to the compact packing of its major components, viz. cellulose, hemicellulose and lignin, high lignin content, and high cellulose crystallinity, is a major bottleneck in its widespread use as a biorefinery feedstock. Typical chemical, thermal, and biological pretreatment technologies are aimed at removing lignin and hemicellulose fractions for improving enzyme accessibility and digestibility of cellulose. This review highlights common pine pretreatment procedures, associated key parameters and resulting enzymatic hydrolysis yields. The challenges and limitations are also discussed as well as potential strategies to overcome them, providing an essential source of information to realize pine as a compelling biorefinery biomass source. [ABSTRACT FROM AUTHOR]

Lignin is a major polymer in the secondary plant cell wall and composed of hydrophobic interlinked hydroxyphenylpropanoid units. The presence of lignin hampers conversion of plant biomass into biofuels; plants with modified lignin are therefore being investigated for increased digestibility. The bacterium Sphingomonas paucimobilis produces lignin-degrading enzymes including LigD, LigF and LigG involved in cleaving the most abundant lignin interunit linkage, the β-aryl ether bond. In this study, we expressed the LigD, LigF and LigG ( Lig DFG) genes in Arabidopsis thaliana to introduce postlignification modifications into the lignin structure. The three enzymes were targeted to the secretory pathway. Phenolic metabolite profiling and 2D HSQC NMR of the transgenic lines showed an increase in oxidized guaiacyl and syringyl units without concomitant increase in oxidized β-aryl ether units, showing lignin bond cleavage. Saccharification yield increased significantly in transgenic lines expressing Lig DFG, showing the applicability of our approach. Additional new information on substrate specificity of the Lig DFG enzymes is also provided. [ABSTRACT FROM AUTHOR]

Recently, seaweeds have gained attention as possible renewable sources for biofuel and bioproduct production. To investigate the possibility of using green seaweeds as biomass feedstocks, the chemical composition and saccharification yield of the green seaweed Ulva pertusa were investigated. In this study, we evaluated U. pertusa that was harvested from the seashore in Jeju Island, Korea. By proximate composition analysis, dried U. pertusa was found to contain 52.3% carbohydrate, 25.1% protein, 0.1% lipid, and 22.5% ash. The elemental analysis of U. pertusa indicated the content of carbon to be 34.9%, hydrogen 5.3%, oxygen 46.5%, nitrogen 3.8%, sulfur 3.1%, and phosphorous 0.12%. The optimal conditions for the acid hydrolysis and saccharification of U. pertusa were investigated by varying the types of catalysts, catalyst concentration, reaction time, reaction temperature, and seaweed concentration. Under optimized acid hydrolysis condition, 32.9% of seaweed was recovered as monosaccharides and the monosaccharide composition was 11.5% D-glucuronic acid and D-glucuronic acid lactone, 11.1% L-rhamnose, 6.7% D-glucose, and 3.7% D-xylose. The concept of degree of reductance was introduced to assess the potential of U. pertusa as an industrial feedstock. It was found that the degree of reductance of U. pertusa was lowest among the biomass considered in this study. Based on the comparison of chemical composition and reductance degree of various biomass resources, the competitiveness of U. pertusa as a biomass feedstock for biofuel and bioproduct production was discussed. [ABSTRACT FROM AUTHOR]

Sorghum ( Sorghum bicolor (L.) Moench) is a high-yielding, stress tolerant energy crop for lignocellulosic-based biofuel production. Saccharification is a process by which hydrolytic enzymes break down lignocellulosic materials to fermentable sugars for biofuel production, and mapping and identifying genes underlying saccharification yield is an important first step to genetically improve the plant for higher biofuel productivity. In this study, we used the ICRISAT sorghum mini core germplasm collection and 14 739 single nucleotide polymorphism markers to map saccharification yield. Seven marker loci were associated with saccharification yield and five of these loci were syntenic with regions in the maize genome that contain quantitative trait loci underlying saccharification yield and cell wall component traits. Candidate genes from the seven loci were identified but must be validated, with the most promising candidates being β-tubulin, which determines the orientation of cellulose microfibrils in plant secondary cell walls, and NST1, a master transcription factor controlling secondary cell wall biosynthesis in fibers. Other candidate genes underlying the different saccharification loci included genes that play a role in vascular development and suberin deposition in plants. The identified loci and candidate genes provide information into the factors controlling saccharification yield and may facilitate increasing biofuel production in sorghum. [ABSTRACT FROM AUTHOR]

Saccharification describes the conversion of plant biomass by cellulase into glucose. Because plants have never been selected for high saccharification yield, cellulosic ethanol production faces a significant bottleneck. To improve saccharification yield, it is critical to identify the genes that affect this process. In this study, we used pool-based genome-wide association mapping to identify simple sequence repeat (SSR) markers associated with saccharification yield. Screening of 703 SSR markers against the low and high saccharification pools identified two markers on the sorghum chromosomes 2 (23-1062) and 4 (74-508c) associated with saccharification yield. The association was significant at 1% using either general or mixed linear models. Localization of these markers based on the whole genome sequence indicates that 23-1062 is 223 kb from a β-glucanase (Bg) gene and 74-508c is 81 kb from a steroid-binding protein (Sbp) gene. Bg is critical for cell wall assembly and degradation, but Sbp can suppress the expression of Bg as demonstrated in Arabidopsis (Yang et al. 2005). These markers are found physically close to genes encoding plant cell wall synthesis enzymes such as xyloglucan fucosyltransferase (149 kb from 74-508c) and UDP-D-glucose 4-epimerase (46 kb from 23-1062). Genetic transformation of selected candidate genes is in progress to examine their effect on saccharification yield in plants. [ABSTRACT FROM AUTHOR]

• Isolated Lysinibacillus sp. RGS showed ability to produce PHB using various carbon sources. • Lysinibacillus sp. could effectively utilize chemically pretreated SCB as a solitary carbon source. • Achieved maximum cell growth (8.65 g/L) and PHB titer (5.31 g/L) under optimal conditions. • Chemical structure of the extracted PHB found identical with the standard PHB. In this study, Lysinibacillus sp. RGS was evaluated to synthesize polyhydroxybutyrate (PHB) from a broad range of pure carbon sources and residual sugars of chemically pretreated sugarcane bagasse (SCB) hydrolysates. Effects of supplementation of nutrients and various experimental variables to enhance PHB accumulation were investigated. Results of optimized parameters were identified as 48 h, 37 °C, pH 7; inoculums concentration (2.5% v/v) and shaking condition (100 rpm). Growth kinetics and bioprocess parameters of Lysinibacillus sp. using SCB hydrolysates with corn steep liquor (2%) accounted for the maximum cell growth (8.65 g/L) and PHA accumulation (61.5%) with PHB titer of (5.31 g/L) under optimal conditions. The produced biopolymer was studied by Fourier Transform Infrared (FTIR) spectroscopy and the results revealed the obtained to be PHB. Thus Lysinibaciluus sp. exhibits high potential in industrial scale manufacture of PHB using SCB as an inexpensive substrate. [ABSTRACT FROM AUTHOR]