Production of biofuels from soybean straw and hull hydrolysates obtained by subcritical water hydrolysis

Identification and Genetic Dissection of Resistance to Red Crown Rot Disease in a Diverse Soybean Germplasm Population

Red crown rot (RCR) disease caused by Calonectria ilicicola negatively impacts soybean yield and quality. Unfortunately, the knowledge of the genetic architecture of RCR resistance in soybeans is limited. In this study, 299 diverse soybean accessions were used to explore their genetic diversity and resistance to RCR, and to mine for candidate genes via emergence rate (ER), survival rate (SR), and disease severity (DS) by a multi-locus random-SNP-effect mixed linear model of GWAS. All accessions had brown necrotic lesions on the primary root, with five genotypes identified as resistant. Nine single-nucleotide polymorphism (SNP) markers were detected to underlie RCR response (ER, SR, and DS). Two SNPs colocalized with at least two traits to form a haplotype block which possessed nine genes. Based on their annotation and the qRT-PCR, three genes, namely Glyma.08G074600, Glyma.08G074700, and Glyma.12G043600, are suggested to modulate soybean resistance to RCR. The findings from this study could serve as the foundation for breeding RCR-tolerant soybean varieties, and the candidate genes could be validated to deepen our understanding of soybean response to RCR.

Semi-continuous hydrothermal processing of pine sawdust for integrated production of fuels precursors and platform chemicals

This research reports data for the integrated obtaining of fermentable sugars (FSs), bio-oil (BO), and hydro-char (HC) - all fuel precursors - as well as platform chemicals (PCs - acetic, formic, and levulinic acid, besides furfural, and hydroxymethylfurfural) through semi-continuous hydrothermal processing of sawdust from pine wood. The influence of temperature (260, 300, and 340 °C) and the water-to-biomass ratio (25 and 50 g H2O (g biomass)-1) were the parameters considered to evaluate the mass yields, kinetic profiles, and BO properties. For FSs (and PCs), a detailed analysis considering the kinetic profiles of obtaining cellobiose, glucose, xylose, and arabinose is presented. For the conditions evaluated, a distinct behavior concerning the process parameters was observed, where 7.11 and 9.28 g (100 g biomass)-1 of FSs and PCs were synergistically obtained, respectively, after 30 min, 20 MPa, 260 °C, and 50 g H2O (g biomass)-1. Contextually, 17.59 g (100 g biomass)-1 of BO was obtained at 340 °C and the same water/biomass ratio. FTIR analysis of the BO samples suggested the presence of aldehydes, carboxylic acids, ketones, hydrocarbons, ethers as well as aromatic, alcohols, and nitrogenous compounds. Similar HC yields were achieved among the conditions analyzed, where 24.68 g (100 g biomass)-1 were obtained at 340 °C and 50 g H2O (g biomass)-1 for a higher heating value of 29.14 MJ kg-1 (1.5 times higher than the in natura biomass).

Production of enzymes for the removal of odorous substances in plant biomass

Residual plant biomass collected from agricultural, technical or biopharmaceutical processes contains odorous substances. The latter are often unacceptable for customers if the biomass is used in sustainable products such as building materials, paints, glues or flame-resistant foils. The objective of this study was to identify enzymes that can prevent the formation or facilitate the degradation of odorous substances such as butanol, eugenol or ethyl acetate and their derivatives in residual biomass. We used plant cell packs (PCPs) as a small-scale screening platform to assess the expression of enzymes that break down odorous substances in tobacco biomass. First, we compiled a list of volatile compounds in residual plant biomass that may give rise to undesirable odors, refining the list to 10 diverse compounds representing a range of odors. We then selected five monomeric enzymes (a eugenol oxidase, laccase, oxidase, alkane mono-oxidase and ethyl acetate hydrolase) with the potential to degrade these substances. We transiently expressed the proteins in PCPs, targeting different subcellular compartments to identify optimal production conditions. The maximum yield we achieved was ∼20 mg kg-1 for Trametes hirsute laccase targeted to the chloroplast. Our results confirm that enzymes for the removal of odorous substances can be produced in plant systems, facilitating the upcycling of residual biomass as an ingredient for sustainable products.

Advanced biofuel production, policy and technological implementation of nano-additives for sustainable environmental management - A critical review

This review article critically evaluates the significance of adopting advanced biofuel production techniques that employ lignocellulosic materials, waste biomass, and cutting-edge technology, to achieve sustainable environmental stewardship. Through the analysis of conducted research and development initiatives, the study highlights the potential of these techniques in addressing the challenges of feedstock supply and environmental impact and implementation policies that have historically plagued the conventional biofuel industry. The integration of state-of-the-art technologies, such as nanotechnology, pre-treatments and enzymatic processes, has shown considerable promise in enhancing the productivity, quality, and environmental performance of biofuel production. These developments have improved conversion methods, feedstock efficiency, and reduced environmental impacts. They aid in creating a greener and sustainable future by encouraging the adoption of sustainable feedstocks, mitigating greenhouse gas emissions, and accelerating the shift to cleaner energy sources. To realize the full potential of these techniques, continued collaboration between academia, industry representatives, and policymakers remains essential.

Genome-Wide Association Analysis for Resistance to Coniothyrium glycines Causing Red Leaf Blotch Disease in Soybean

Soybean is a high oil and protein-rich legume with several production constraints. Globally, several fungi, viruses, nematodes, and bacteria cause significant yield losses in soybean. Coniothyrium glycines (CG), the causal pathogen for red leaf blotch disease, is the least researched and causes severe damage to soybean. The identification of resistant soybean genotypes and mapping of genomic regions associated with resistance to CG is critical for developing improved cultivars for sustainable soybean production. This study used single nucleotide polymorphism (SNP) markers generated from a Diversity Arrays Technology (DArT) platform to conduct a genome-wide association (GWAS) analysis of resistance to CG using 279 soybean genotypes grown in three environments. A total of 6395 SNPs was used to perform the GWAS applying a multilocus model Fixed and random model Circulating Probability Unification (FarmCPU) with correction of the population structure and a statistical test p-value threshold of 5%. A total of 19 significant marker-trait associations for resistance to CG were identified on chromosomes 1, 5, 6, 9, 10, 12, 13, 15, 16, 17, 19, and 20. Approximately 113 putative genes associated with significant markers for resistance to red leaf blotch disease were identified across soybean genome. Positional candidate genes associated with significant SNP loci-encoding proteins involved in plant defense responses and that could be associated with soybean defenses against CG infection were identified. The results of this study provide valuable insight for further dissection of the genetic architecture of resistance to CG in soybean. They also highlight SNP variants and genes useful for genomics-informed selection decisions in the breeding process for improving resistance traits in soybean.

Critical review of biochemical pathways to transformation of waste and biomass into bioenergy

In recent years, biofuel or biogas have become the primary source of bio-energy, providing an alternative to conventionally used energy that can meet the growing energy demand for people all over the world while reducing greenhouse gas emissions. Enzyme hydrolysis in bioethanol production is a critical step in obtaining sugars fermented during the final fermentation process. More efficient enzymes are being researched to provide a more cost-effective technique during enzymatic hydrolysis. The exploitation of microbial catabolic biochemical reactions to produce electric energy can be used for complex renewable biomasses and organic wastes in microbial fuel cells. In hydrolysis methods, a variety of diverse enzyme strategies are used to promote efficient bioethanol production from various lignocellulosic biomasses like agricultural wastes, wood feedstocks, and sea algae. This paper investigates the most recent enzyme hydrolysis pathways, microbial fermentation, microbial fuel cells, and anaerobic digestion in the manufacture of bioethanol/bioenergy from lignocellulose biomass.

Subcritical water pretreatment enhanced methane-rich biogas production from the anaerobic digestion of brewer's spent grains

ABSTRACTThis study evaluated the effectiveness of a semi-continuous flow-through subcritical water hydrolysis (SWH) pretreatment of brewer's spent grains (BSG) for subsequent application in the anaerobic digestion (AD) process. BSG pretreatment was conducted at 160 °C and 15 MPa with a flow rate of 10 mL water min-1 and 15 g water g-1 BSG. The results revealed that SWH attacked the hemicellulose structure, releasing arabinose (46.54 mg g-1) and xylose (39.90 mg g-1) sugars, and proteins (34.89 mg g-1). The start-up of anaerobic reactors using pretreated BSG (747.71 L CH4 kg-1 TVS) increased the methane yield compared with the reactor without pretreatment (53.21 L CH4 kg-1 TVS). For the process with pretreatment, the generation of electricity (134 kWh t-1 BSG) and heat (604 MJ t-1) are responsible for the mitigation of 43.90 kg CO2 eq t-1 BSG. The adoption of SWH as an eco-friendly pretreatment of biomass for AD could be a technological route to increase methane-rich biogas and bioenergy production, supporting the circular economy transition by reducing the carbon footprint of the beer industry.

Inhibition of cellulase activity by liquid hydrolysates from hydrothermally pretreated soybean straw

The one-pot biomass conversion process is a promising strategy to minimize potential product loss and reduce processing costs. However, this strategy has technical limitations due to the inhibitory effects of biomass components like lignin as well as the generated inhibitors (e.g., furans, phenols) during biomass processing. In this study, the inhibitory effects of liquid hydrolysates formed by hydrothermal pretreatment of soybean straw with either sodium hydroxide (NaOH) or hydrogen peroxide (H2O2) on cellulolytic enzyme activity were investigated. Hydrothermal pretreatment of soybean straw (10% w/v) was carried out with either sodium hydroxide (1% v/v) or hydrogen peroxide (1% v/v) at 121°C for 60 min to evaluate the effect of water-soluble inhibitors released from soybean pretreatment on cellulolytic enzyme activity. The fraction of cellulose in pretreated solids (1% w/v glucan) was enzymatically hydrolyzed for 72 h with 45 IU/g glucan (corresponding to 25 mg enzyme protein/g glucan) in the presence of either buffer or liquid hydrolysate generated from the pretreatments. Hydrolysis of NaOH and H2O2 pretreated solids resulted in 57% and 39% of glucose yields in buffer, respectively. In the presence of the liquid hydrolysates, NaOH and H2O2 pretreated biomass showed 20% and 30% glucose yield, respectively, indicating the enzyme suppression by inhibitors in the liquid hydrolysates. Of the enzyme activities in hydrolysates tested, NaOH hydrolysate showed a higher inhibitory effect on enzyme activities (mainly β-glucosidase) compared to H2O2 liquid, where enzyme deactivation has a first-order correlation and the manner in which the vacuum-filtered inhibitors were generated from pretreated soybean straw.

Adsorption of basic fuchsin using soybean straw hydrolyzed by subcritical water

The valorization of agro-industrial residues can be improved through their full use, making the production of second-generation ethanol viable. In this scenario, hydrolyzed soybean straw generated from a subcritical water process was applied to the basic fuchsin adsorption. At pH eight, a high adsorption capacity was obtained. The mass test results showed that basic fuchsin's removal and adsorption capacity could be maximized with an adsorbent dosage of 0.9 g L-1. The linear driving force model was suitable for predicting the kinetic profile, and the kinetic curves showed that equilibrium was reached with only 30 min of contact time. Besides, the Langmuir model was the best to predict the adsorption isotherms. The thermodynamic parameters revealed a spontaneous and endothermic process. At 328 K, there is maximum adsorption capacity (72.9 mg g-1). Therefore, it can be stated that this material could be competitive in terms of adsorption capacity coupled with the idea of full use of waste.

Defatted rice bran pretreated with deep eutectic solvents and sequential use as feedstock for subcritical water hydrolysis

Deffated rice bran has potential to processing into ethanol due to its lignocellulosic composition and agricultural productivity. The composition of the pretreated deffated rice bran with Deep Eutectic Solvent was investigated aiming the production of sugars and bioproducts using subcritical water hydrolysis. Changes in the deffated rice bran composition at different pretreatment times and mixtures of deep eutectic solvent were evaluated by the derivative of thermogravimetric analysis. The pretreated deffated rice bran presented an enrichment in the content of hemicelluloses (281.0%) and delignification (59.3 %). Under the same condition of subcritical water hydrolysis (230 °C/R-100) the yield of fermentable sugars increased 2.20 times in the same study time interval (20 min) when comparing pretreated and untreated deffated rice bran.

Soybean hulls as carbohydrate feedstock for medium to high-value biomolecule production in biorefineries: A review

Soybean is one of the major world crops, with an annual production of 359 million tons. Each ton of processed soybean generates 50-80 kg of soybean hulls (SHs), representing 5-8% of the whole seed. Due to environmental concerns and great economic potential, the search of SHs re-use solutions are deeply discussed. The lignocellulosic composition of SHs has attracted the attention of the scientific and productive sector. Recently, some studies have reported the use of SHs in the production of medium to high value-added molecules, with potential applications in food and feed, agriculture, bioenergy, and other segments. This review presents biotechnological approaches and processes for the management and exploitation of SHs, including pre-treatment methods and fermentation techniques, for the production of different biomolecules. Great potentialities and innovations were found concerning SH exploration and valorisation of the soybean chain under a biorefinery and circular bioeconomy optic.