Strategy for the analysis of lignocellulosic biomass to select a viable transformation route in the Colombian context.

Lignocellulosic biomass is widely available in the world. However, a consensus has yet to be established to evaluate the biomass valorization alternatives. The chemical composition is the primary technical limitation in selecting a transformation route to obtain value-added products. In this paper, the bagasse from non-centrifuged sugar (NCS) production and Pinus patula (PP) wood chips were analyzed in terms of complete chemical composition to establish their potential for selecting the transformation routes. A strategy to select the best route based on the chemical composition was applied and a feedstock criteria model was proposed. Schemes were obtained and compared using a bioprocess selection strategy proposed in previous works. As a result, the preliminary biorefinery schemes were finally defined. The assessment of schemes derived from the outlined strategy included technical, economic, environmental, and social analyses. The environmental evaluation was complemented with a geolocation assessment, revealing a 0.75-ton CO2-eq/yr contribution to the carbon footprint for local distribution. The sustainability index for the PP biorefinery and the bagasse from NCS production was analyzed, resulting in indices of 44.8 and 60.9, respectively. These values were primarily derived from the economic and environmental analyses of both processes.

Potential of Plantain Pseudostems (Musa AAB Simmonds) for Developing Biobased Composite Materials.

A plantain pseudostem was harvested and processed on the same day. The process began with manually separating the sheaths (80.85%) and the core (19.14%). The sheaths were subjected to a mechanical shredding process using paddles, extracting 2.20% of lignocellulosic fibers and 2.12% of sap, compared to the fresh weight of the sheaths. The fibers were washed, dried, combed, and spun in their native state and subjected to a steam explosion treatment, while the sap was subjected to filtration and evaporation. In the case of the core, it was subjected to manual cutting, drying, grinding, and sieving to separate 12.81% of the starch and 6.39% of the short lignocellulosic fibers, compared to the fresh weight of the core. The surface modification method using steam explosion succeeded in removing a low proportion of hemicellulose and lignin in the fibers coming from the shims, according to what was shown by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC), achieving increased σmax and ε from the tensile test and greater thermal stability compared to its native state. The sap presented hygroscopic behavior by FT-IR and the highest thermal stability from TGA, while the starch from the core presented the lowest hygroscopic character and thermal stability. Although the pseudostem supplied two types of fibers, lower lignin content was identified in those from the core. Finally, the yarns were elaborated by using the fibers of the sheaths in their native and steam-exploded states, identifying differences in the processing and their respective physical and mechanical properties.

Xylooligosaccharides: A Bibliometric Analysis and Current Advances of This Bioactive Food Chemical as a Potential Product in Biorefineries' Portfolios.

Xylooligosaccharides (XOS) are nondigestible compounds of great interest for food and pharmaceutical industries due to their beneficial prebiotic, antibacterial, antioxidant, and antitumor properties. The market size of XOS is increasing significantly, which makes its production from lignocellulosic biomass an interesting approach to the valorization of the hemicellulose fraction of biomass, which is currently underused. This review comprehensively discusses XOS production from lignocellulosic biomass, aiming at its application in integrated biorefineries. A bibliometric analysis is carried out highlighting the main players in the field. XOS production yields after different biomass pretreatment methods are critically discussed using Microsoft PowerBI® (2.92.706.0) software, which involves screening important trends for decision-making. Enzymatic hydrolysis and the major XOS purification strategies are also explored. Finally, the integration of XOS production into biorefineries, with special attention to economic and environmental aspects, is assessed, providing important information for the implementation of biorefineries containing XOS in their portfolio.

Oxidative Machinery of basidiomycetes as potential enhancers in lignocellulosic biorefineries: A lytic polysaccharide monooxygenases approach.

Basidiomycetes are renowned as highly effective decomposers of plant materials, due to their extensive array of oxidative enzymes, which enable them to efficiently break down complex lignocellulosic biomass structures. Among the oxidative machinery of industrially relevant basidiomycetes, the role of lytic polysaccharide monooxygenases (LPMO) in lignocellulosic biomass deconstruction is highlighted. So far, only a limited number of basidiomycetes LPMOs have been identified and heterologously expressed. These LPMOs have presented activity on cellulose and hemicellulose, as well as participation in the deconstruction of lignin. Expanding on this, the current review proposes both enzymatic and non-enzymatic mechanisms of LPMOs for biomass conversion, considering the significance of the Carbohydrate-Binding Modules and other C-terminal regions domains associated with their structure, which is involved in the deconstruction of lignocellulosic biomass.

Analysis of Single-Step Pretreatments for Lignocellulosic Platform Isolation as the Basis of Biorefinery Design.

Biorefinery feasibility is highly influenced by the early design of the best feedstock transformation pathway to obtain value-added products. Pretreatment has been identified as the critical stage in biorefinery design since proper pretreatment influences subsequent reaction, separation, and purification processes. However, many pretreatment analyses have focused on preserving and valorizing six-carbon sugars for future use in bioconversion processes, leaving aside fractions such as hemicellulose and lignin. To date, there has been no pretreatment systematization for the removal of lignocellulosic fractions. This work defines pretreatment efficacy through operational, economic, environmental, and social indicators. Thus, using the data reported in the literature, as well as the results of the simulation schemes, a multi-criteria weighting of the best-performing schemes for the isolation or removal of cellulose, hemicellulose, and lignin was carried out. As a main result, it was concluded that dilute acid is the most effective for cellulose isolation and hemicellulose removal for producing platform products based on six- and five-carbon sugars, respectively. Additionally, the kraft process is the best methodology for lignin removal and its future use in biorefineries. The results of this work help to elucidate a methodological systematization of the pretreatment efficacy in the design of biorefineries as an early feasibility stage considering sustainability aspects.

Microalgae-Based Biorefineries: Challenges and Future Trends to Produce Carbohydrate Enriched Biomass, High-Added Value Products and Bioactive Compounds.

Microalgae have demonstrated a large potential in biotechnology as a source of various macromolecules (proteins, carbohydrates, and lipids) and high-added value products (pigments, poly-unsaturated fatty acids, peptides, exo-polysaccharides, etc.). The production of biomass at a large scale becomes more economically feasible when it is part of a biorefinery designed within the circular economy concept. Thus, the aim of this critical review is to highlight and discuss challenges and future trends related to the multi-product microalgae-based biorefineries, including both phototrophic and mixotrophic cultures treating wastewater and the recovery of biomass as a source of valuable macromolecules and high-added and low-value products (biofertilizers and biostimulants). The therapeutic properties of some microalgae-bioactive compounds are also discussed. Novel trends such as the screening of species for antimicrobial compounds, the production of bioplastics using wastewater, the circular economy strategy, and the need for more Life Cycle Assessment studies (LCA) are suggested as some of the future research lines.

Aerobic post-treatment of effluent from anaerobic reactors fed with residues from 1G and 2G sugarcane biorefineries.

This study aimed to evaluate an activated sludge system as a post-treatment step of anaerobic effluents from the co-digestion of sugarcane vinasse and hemicelluloses hydrolysate. The system consisted, initially, of a two-stage anaerobic system followed by a continuously fed activated sludge, all in bench scale. After adaptation of aerobic microorganisms to effluent conditions, the anaerobic digestion was conducted in a single-stage anaerobic reactor, increasing the influent organic loading rate (OLR) of activated sludge from 0.73 to an average of 2.36 gCOD/L·day. Under optimal conditions (12-h hydraulic retention time [HRT]), a 62 ± 9% efficiency was observed on the aerobic post-treatment, resulting in effluent chemical oxygen demand (COD) of 414.3 ± 95 mg/L. Overall efficiency of the combined system (anaerobic + aerobic) averaged 88 ± 3%. Influent and effluent characteristics were then analyzed by Folin-Ciocalteau method, UV-Vis spectrophotometry, and gas chromatography-mass spectrometry (GC-MS) for identification of potentially toxic and recalcitrant compounds. Compounds that absorb light within the visible spectra were well removed by the combined treatment system. Most compounds identified by GC-MS in the influent were completely removed by aerobic microorganisms. Saturated fatty acids such as adipic acid, hexadecanoic acid, and octadecanoic acid were observed in the final effluent, as well as other potentially toxic compounds such as stigmasterol, di-isobutyl phthalate, and benzene. Activated sludge proved to be an efficient post-treatment for anaerobic co-digestion, able to cope with changes of anaerobic effluent quality and providing a final effluent of stable organic load. However, phenol removal was not efficient and further studies could be performed to optimize its degradation. PRACTITIONER POINTS: Conventional activated sludge with a 12-h HRT was capable of handling significant OLR variation, providing a final effluent with lower and stable COD concentration. Glucose addition for carbon supplementation was necessary during the start-up of activated sludge. Compounds that absorb light within the visible spectra were mostly removed by the combined (anaerobic-aerobic) treatment system. Most potentially toxic compounds were well removed in the post-treatment system. Saturated fatty acids, VFA, phenols, and low molecular weight aromatic compounds remained in the final effluent.

Mining novel cis-regulatory elements from the emergent host Rhodosporidium toruloides using transcriptomic data.

The demand for robust microbial cell factories that produce valuable biomaterials while resisting stresses imposed by current bioprocesses is rapidly growing. Rhodosporidium toruloides is an emerging host that presents desirable features for bioproduction, since it can grow in a wide range of substrates and tolerate a variety of toxic compounds. To explore R. toruloides suitability for application as a cell factory in biorefineries, we sought to understand the transcriptional responses of this yeast when growing under experimental settings that simulated those used in biofuels-related industries. Thus, we performed RNA sequencing of the oleaginous, carotenogenic yeast in different contexts. The first ones were stress-related: two conditions of high temperature (37 and 42°C) and two ethanol concentrations (2 and 4%), while the other used the inexpensive and abundant sugarcane juice as substrate. Differential expression and functional analysis were implemented using transcriptomic data to select differentially expressed genes and enriched pathways from each set-up. A reproducible bioinformatics workflow was developed for mining new regulatory elements. We then predicted, for the first time in this yeast, binding motifs for several transcription factors, including HAC1, ARG80, RPN4, ADR1, and DAL81. Most putative transcription factors uncovered here were involved in stress responses and found in the yeast genome. Our method for motif discovery provides a new realm of possibilities in studying gene regulatory networks, not only for the emerging host R. toruloides, but for other organisms of biotechnological importance.

Influence of products portfolio and process contextualization on the economic performance of small- and large-scale avocado biorefineries.

This research paper seeks to evaluate the influence of the context, processing scale, and portfolio of products on the economic performance of different avocado-based biorefineries. For this, two scenarios in small and large-scale biorefineries were compared. The case of scenario 1 (avocado oil, animal feed, and electricity production) was the best small-scale alternative to be implemented in rural zones than scenario 2 (guacamole and electricity production). The minimum Processing Scale for Economic Feasibility was 0.85 and 1.1 ton/day for scenarios 1 and 2. Compared to lactic acid and xylitol production, the large-scale process addressed to produce levulinic acid, furfural, and lignin (scenario 1) was the best option (scenario 2). In scenario 1, the minimum Processing Scale for Economic Feasibility was 15.50 ton/day compared with scenario 2 of 41.95 ton/day. Based on these values, scenario 1 has the highest feasibility of being implemented in countries such as Colombia.

Biorefineries as the base for accomplishing the sustainable development goals (SDGs) and the transition to bioeconomy: Technical aspects, challenges and perspectives.

Sustainable development goals (SDGs) are guidelines to improve the socio-economic and environmental worldwide situation caused by excessive fossil fuel use. These goals must be accomplished before 2030 by implementing a national sustainable development framework in all UN country members. Instead, biorefineries are the seed towards a more sustainable world since biomass upgrading into a series of value-added products and energy vectors can reduce current issues related to waste generation and climate change. Besides, biorefineries are the first step on the way to implement a bioeconomy. This review paper aims to elucidate the existing relation between biorefineries, bioeconomy, and the SDGs through a comprehensive analysis of the technical requirements, challenges, and perspectives of biomass upgrading processes. In this way, this review paper includes a discussion about the biorefinery, bioeconomy, sustainable development, and sustainability concepts. Moreover, this paper elucidates how the implementation of biorefineries is linked to the SDGs accomplishment.

Overexpression of a Sugarcane BAHD Acyltransferase Alters Hydroxycinnamate Content in Maize Cell Wall.

The purification of hydroxycinnamic acids [p-coumaric acid (pCA) and ferulic acid (FA)] from grass cell walls requires high-cost processes. Feedstocks with increased levels of one hydroxycinnamate in preference to the other are therefore highly desirable. We identified and conducted expression analysis for nine BAHD acyltransferase ScAts genes from sugarcane. The high conservation of AT10 proteins, together with their similar gene expression patterns, supported a similar role in distinct grasses. Overexpression of ScAT10 in maize resulted in up to 75% increase in total pCA content. Mild hydrolysis and derivatization followed by reductive cleavage (DFRC) analysis showed that pCA increase was restricted to the hemicellulosic portion of the cell wall. Furthermore, total FA content was reduced up to 88%, resulting in a 10-fold increase in the pCA/FA ratio. Thus, we functionally characterized a sugarcane gene involved in pCA content on hemicelluloses and generated a C4 plant that is promising for valorizing pCA production in biorefineries.

Study of biorefineries based on experimental data: production of bioethanol, biogas, syngas, and electricity using coffee-cut stems as raw material.

Energy-driven biorefineries can be designed considering biotechnological and thermochemical conversion pathways. Nevertheless, energy and environmental comparisons are necessary to establish the best way to upgrade lignocellulosic biomass and set the requirements of these processes in different scenarios. This paper aims to evaluate experimentally a biorefinery producing energy vectors using coffee-cut stems (CCS) as feedstock. The obtained yields were the basis for energy and environmental analysis, in two different biorefinery scenarios: (i) production of bioethanol and biogas and (ii) production of syngas and electricity. The energy results indicated that the overall energy efficiency calculated in the first scenario was only 9.15%. Meanwhile, the second biorefinery configuration based on thermochemical routes presented an energy efficiency value of 70.89%. This difference was attributed to the higher consumption of utilities in the biorefinery based on biotechnological routes. The environmental results showed that the impact category of climate change for the first biorefinery (i.e., 0.0193 kg CO2 eq./MJ) had a lower value than that of the second process (i.e., 0.2377 kg CO2 eq./MJ). Thus, the biorefinery based on the biotechnological route presented a better environmental performance. Additionally, the results for both biorefineries allowed concluding that the inclusion of by-products and co-products in the calculation of the environmental analysis can dramatically affect the results.

Kraft lignin fractionation by organic solvents: Correlation between molar mass and higher heating value.

The new concept of integrated biorefineries has significantly changed pulp and paper industries. Lignin, which until then was only burned to generate energy, is now an important raw material for new products production. Kraft lignin (KL) fractions obtained by sequential fractionation with five organic solvents. This sequence allows to extract fractions from lower molar mass to higher molar one, resulting in more homogeneous samples. Lignin's fractions were characterized by FTIR, GPC, TGA and Higher Heating Value (HHV). HHV for KL was 24966, the lowest being 17,891 (F5) and the highest being 27051 J/g (F1), inversely proportional to the molar masses of fractions. This is a very important result indicating that the lower HHV fractions can be used for certain applications, such as antioxidants, additives, polymers, among others, adding value to kraft lignin. Fractions with higher HHV could be used for energy generation in the cellulose paper industry.

Assessment of wasteland derived biomass for bioethanol production

Background: The bioethanol produced from biomass is a promising alternative fuel. The lignocellulose from marginal areas or wasteland could be a promising raw material for bioethanol production because it is present in large quantities, is cheap, renewable and has favorable environmental properties. Despite these advantages, lignocellulosic biomass is much more difficult to process than cereal grains, due to the need for intensive pretreatment and relatively large amounts of cellulases for efficient hydrolysis. Therefore, there is a need to develop an efficient and cost-effective method for the degradation and fermentation of lignocellulosic biomass to ethanol. Results: The usefulness of lignocellulosic biomass from wasteland for the production of bioethanol using pretreatment with the aid of ionic liquids of 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium chloride was evaluated in this study. The pretreatment process, enzymatic hydrolysis and alcoholic fermentation lasted a total of 10 d. The largest amounts of bioethanol were obtained from biomass originating from agricultural wasteland, in which the dominant plant was fireweed (Chamaenerion angustifolium) and from the field where the common broom (Cytisus scoparius) was the dominant. Conclusions: The plants such as fireweed, common broom, hay and goldenrod may be useful for the production of liquid biofuels and it would be necessary in the further stage of research to establish and optimize the conditions for the technology of ethyl alcohol producing from these plant species. Enzymatic hydrolysis of biomass from agricultural wastelands results in a large increase in fermentable sugars, comparable to the enzymatic hydrolysis of rye, wheat, rice or maize straw.

Xylitol bioproduction: state-of-the-art, industrial paradigm shift, and opportunities for integrated biorefineries.

Recent advances in biomass conversion technologies have shown a promising future toward fermentation during xylitol production. Xylitol is one of the top 12 renewable added-value chemicals that can be obtained from biomass according to US Department of Energy (USDOE). Currently, xylitol accounts for approximately US$823.6 million of annual sales in the market, and this amount is expected to reach US$1.37 billion by 2025. This high demand has been achieved owing to the chemical conversion of hemicellulosic hydrolysates from different lignocellulosic biomasses, which is a costly and non-ecofriendly process. Xylose-rich hemicellulosic hydrolysates are the major raw materials for xylitol production through either chemical or biotechnological routes. Economic production of a clean hemicellulosic hydrolysate is one of the major bottlenecks for xylitol production on the commercial scale. Advancements in biotechnology, such as the isolation of novel microorganisms, genetic manipulation of xylose metabolizing strains, and modifications in the fermentation process, can enhance the economic feasibility of xylitol production on the large scale. Furthermore, xylitol production in integrated biorefineries can be even more economic, given the readily available raw materials and the co-use of steam, electricity, and water, among others. Exploring new biotechnology techniques in integrated biorefineries would open new markets and opportunities for sustainable xylitol production to fulfill the market's growing demands for this sugar alcohol. This article is a review of the advancements reported in the whole biotechnological process for xylitol production, and involve pretreatment technologies, hemicellulosic hydrolysate preparation, xylose conversion into xylitol, and product recovery. Special attention is devoted to current metabolic engineering strategies to improve this bioprocess, as well as to the importance of xylitol production processes in biorefineries.

Integral use of plants and their residues: the case of cocoyam (Xanthosoma sagittifolium) conversion through biorefineries at small scale.

During last decades, there has been a growing interest of decreasing the environmental impact generated by humans. This situation has been approached from different perspectives being the integral use of raw materials as one of the best alternatives. It was estimated that 3.7 × 109 tonnes of agricultural residues are produced annually worldwide. Then, the integral use of feedstocks has been studied through the biorefinery concept. A biorefinery can be a promissory option for processing feedstocks in rural zones aiming to boost the techno-economic and social growth. However, many plants produced at small scale in rural zones without high industrial use contribute with residues usually not studied as raw materials for other processes. Cocoyam (Xanthosoma sagittifolium) is a plant grown extensively in tropical regions. Nigeria, China, and Ghana are the main producers with 1.3, 1.18, and 0.9 million tonnes/year, respectively. In Colombia, there are no technified crops, but it is used where it is grown mainly as animal feed. This plant consists of leaves, stem, and a tuber but the use is generally limited to the leaves, discarding the other parts. These discarded parts have great potential (lignocellulose and starch). This work proposes different processing schemes using the parts of the plant to obtain value-added products, and their techno-economic and environmental assessment. The simulation was performed with Aspen Plus and the economic package was used for the economic assessment. For the environmental assessment, Waste Algorithm Reduction of the U.S. EPA was implemented. The obtained results showed that the integral use of plants under a biorefinery scheme allows obtaining better techno-economic and environmental performance and that small-scale biorefineries can be a promissory option for boosting rural zones.

Production of ethanol and xylitol by Trametes membranacea.

The potential to produce ethanol and xylitol from xylose by the macro basidiomycete Trametes membranacea was evaluated. All strains studied showed ethanol and xylitol production. The highest ethanol production of xylose was obtained by T. membranacea strain TM158/10 with 5.65 ± 0.21 g/L at pH 4 and 28 °C with 288 h of fermentation and 5.59 ± 0.05 g/L ethanol concentration at pH 5 and 24 °C with 360 h of fermentation. When the conversion was carried out using sugars generated from enzymatic hydrolysis of sugarcane bagasse, there were higher yields from 74 to 15% for ethanol and xylitol, respectively. Although the ethanol and xylitol production need to be optimized, this study showed for the first time the possibility of using T. membranacea for the simultaneous xylitol and ethanol production from pentose sugars, allowing for the possibility of using all released sugars during the hydrolysis of lignocelluloses.

High-performance of Agaricus blazei fungus for the biological pretreatment of elephant grass.

Biological pre-treatment seems to be promising being an eco-friendly process, with no inhibitor generated during the process. The potential for elephant grass pre-treatment with white degradation fungi Pleurotus ostreatus, Agaricus blazei, Lentinula edodes, Pleurotus citrinopileatus, and Pleurotus djamor, in isolated or mixed cultures of these strains, was evaluated. The highest activities of enzymes involved in the degradation of lignocellulosic biomass (laccases, endoglucanases, xylanases, and ß-glucosidases) were observed for A. blazei, L. edodes and the combination of P. ostreatus and A. blazei. In the enzymatic hydrolysis, there was greater release of reducing sugars in the pre-treated elephant grass samples by A. blazei during 10 days (338.91 ± 7.39 mg g-1 of biomass). For this sample, higher lignin reductions, 24.81 and 57.45%, after 15 and 35 days of incubation, respectively, were also verified. These data indicate the potential of macromycetes such as A. blazei to perform biological pre-treatments. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:42-50, 2018.

Biological pretreatment of sugarcane bagasse with basidiomycetes producing varied patterns of biodegradation.

This work evaluated sugarcane bagasse pretreatment with wood-decay fungi, producing varied patterns of biodegradation. The overall mass balance of sugars released after pretreatment and enzymatic hydrolysis indicated that a selective white-rot was necessary to provide glucose yields similar to the ones observed from leading physico-chemical pretreatment technologies. The selective white-rot Ceriporiopsis subvermispora was selective for lignin degradation in the lignocellulosic material, preserved most of the glucan fraction, and increased the cellulose digestibility of biotreated material. Glucose mass balances indicated that of the potential glucose of untreated bagasse, 47% was recovered as sugar-rich syrup after C. subvermispora biotreatment for 60days followed by enzymatic digestion of the pretreated material.

Potential application of microalga Spirulina platensis as a protein source.

The high protein level of various microalgal species is one of the main reasons to consider them an unconventional source of this compound. Spirulina platensis stands out for being one of the richest protein sources of microbial origin (460-630 g kg-1 , dry matter basis), having similar protein levels when compared to meat and soybeans. The use of S. platensis in food can bring benefits to human health owing to its chemical composition, since it has high levels of vitamins, minerals, phenolics, essential fatty acids, amino acids and pigments. Furthermore, the development of new protein sources to supply the shortage of this nutrient is an urgent need, and protein from S. platensis plays an important role in this scenario. In this sense, extraction processes that allow maximum protein yield and total utilization of biomass is an urgent need, and ultrasonic waves have proven to be an effective extraction technique. The number of scientific papers related to protein fraction from S. platensis is still limited; thus further studies on its functional and technological properties are needed. © 2016 Society of Chemical Industry.