Hydrolysis Of Sugarcane Bagasse Research Articles

Use of an inexpensive carbon source for the production of a cellulase enzyme complex from Penicillium ucsense S1M29 and enzymatic hydrolysis optimization

AbstractThe high cost of cellulolytic enzyme complexes (CECs) has been a significant impediment to the commercial production of bioproducts from lignocellulose biomass. This study aimed to develop a cost‐effective CEC derived from Penicillium ucsense (former Penicillium echinulatum), utilizing diverse forms of pretreated sugarcane bagasse as the primary carbon/inductor source. Among the different pretreatments used, the hydrothermal pretreatment followed by NaOH delignification (BHD) produced higher FPase and xylanase activities (4.5 FPU mL–1 and 120 IU mL–1) in bioreactor experiments at 20 g BHD L–1 initial concentration. A batch‐mode assay conducted across a range of initial carbon source (5 to 60 g L–1) confirmed the highest FPase activity (4.0 to 5.0 FPU mL–1 at 120 h), in the range of 20–40 g BHD L–1. During these assays the agitation rate, controlled by dissolved O2, tended to stabilize at lower levels, indicating substrate limitation. Conversely, higher initial carbon source concentrations led to an excess of glucose, likely triggering carbon catabolite repression and inhibiting cellulase production. This insight prompted the development of a controlled pulsed fed‐batch strategy, resulting in FPase activity of 11 FPU mL–1 at 220 h using 90 g L–1 BHD controlled fed into the bioreactor. An enzymatic hydrolysis procedure using the generated CEC was also optimized using a central composite rotational design (CCRD). The optimized enzyme hydrolysis conditions achieved a reducing sugar concentration of 80.9 g L–1 in 48 h using 170 g L–1 of BHD as the substrate at a ratio of 15 FPU of enzyme substrate per g of BHD. A preliminary economic assessment demonstrated that, for a first‐ and second‐generation (1G + 2G) ethanol biorefinery, the cost contribution of enzymes would be about US$0.2/L of biofuel. In conclusion, an efficient and highly productive procedure was developed successfully for the production of a CEC. It was particularly effective for the enzymatic hydrolysis of pretreated sugarcane bagasse.

Comparative study for enzymatic hydrolysis of sugarcane bagasse using free and nanoparticle immobilized holocellulolytic enzyme cocktail

This study aimed at a comparative analysis of enzymatic hydrolysis of sugarcane bagasse biomass by using a free holocellulase cocktail of an enzyme (Cellic CTec2) and immobilized enzyme system on IOMNP@SiO2-NH2 support to make the process cost-effective. The immobilization was substantiated by examining the nano biocatalysts using FTIR, TEM, and DLS analysis. IOMNP@SiO2 –NH2 and immobilized enzyme system have average particle sizes of 81.1, and 455.9 nm confirmed by DLS. Response surface methodology (RSM) based on the Box Behnken design was employed to optimize the saccharification process conditions. The free cellulase cocktail showed a maximum hydrolysis yield of 70.71 % at 12.5FPU/gm enzyme dose, while the immobilized enzyme at a dose of 20 FPU/gm achieved a conversion rate of 74.19 % under optimized parameters likes hydrolysis time, surfactant and substrate concentration. Pretreated sugarcane bagasse substrate was used to evaluate the reusability potential of magnetically immobilized cellulase enzyme compared to recovered free enzyme up to 5 cycles. In the second and third cycles, the conversion rates of cellulose to glucose were determined to be 68.21 %, and 52.6 %, respectively. The findings of this study demonstrate that the immobilized Cellic CTec2 enzyme cocktail on functionalized IOMNP is effective for hydrolyzing sugarcane bagasse which also provides the advantages of easy recovery and reusability of enzyme for multiple hydrolysis cycles.

Glycerol Production from Undetoxified Lignocellulose Hydrolysate by a Multiresistant Engineered Candida glycerinogenes.

Glycerol is an important platform compound with multidisciplinary applications, and glycerol production using low-cost sugar cane bagasse hydrolysate is promising. Candida glycerinogenes, an industrial yeast strain known for its high glycerol production capability, has been found to thrive in bagasse hydrolysate obtained through a simple treatment without detoxification. The engineered C. glycerinogenes exhibited significant resistance to furfural, acetic acid, and 3,4-dimethylbenzaldehyde within undetoxified hydrolysates. To further enhance glycerol production, genetic modifications were made to Candida glycerinogenes to enhance the utilization of xylose. Fermentation of undetoxified bagasse hydrolysate by CgS45 resulted in a glycerol titer of 40.3 g/L and a yield of 40.4%. This process required only 1 kg of bagasse to produce 93.5 g of glycerol. This is the first report of glycerol production using lignocellulose, which presents a new way for environmentally friendly industrial production of glycerol.

Sustainable fermentable sugar production using a glass fiber supported gallium–molybdenum photocatalyst towards bioethanol production: LCA analysis

A waste printed circuit board derived glass fiber supported gallium–molybdenum photocatalyst for sustainable hydrolysis of sugarcane bagasse for bioethanol production is reported.

OPTIMIZATION AND QUALITY ANALYSIS OF BIO-BUTANOL PRODUCTION FROM SUGARCANE (Saccharum officinarum) BAGASSE HYDROLYSATE

Several companies are currently investigating in development for the production of Biobutanol. This research was concerned with Biobutanol production from ABE (Acetone, Butanol, and Ethanol) fermentation of sugarcane bagasse hydrolysate by Clostridium Perfringens. The sample was hydrolyzed with concentrated H2SO4 solution for 1 hour at 121oC. Response surface designed by optimizing the fermentation parameters (Time, Temperature, and pH) by the used media (C. Perfringens) showed the highest Biobutanol yield at temperature (350C), Time 48 (Hhs), and pH 6.0 with 163 cm3 which is exactly around 0.543(g/L) by converted to a gram per liter as mostly represented by many researchers. The produced Biobutanol from the sugarcane bagasse hydrolysate was characterized using FT-IR and GC-MS analysis. Conclusively this work revealed the importance of sugarcane bagasse as a good potential feedstock of Biobutanol.

Recycling enzymatic hydrolysis lignin residues saved cellulase in enzymatic hydrolysis of lignocellulose: An insight from cellulase adsorption mechanism

Enzymatic hydrolysis lignin residues (EHLRs) of lignocellulose usually adsorbs cellulase, which can be recycled and used to replace parts of cellulase in the hydrolysis process. To understand this phenomenon during enzymatic hydrolysis (EH) of sugarcane bagasse (SCB) treated with sulfite (SPORL) and dilute acid (DA), the adsorption characteristics between lignin and cellulase in EHLRs were investigated, focusing on interaction force at molecular level and enzymatic activity. The results revealed that SPORL-EHLR adsorbed more β-glucosidases (β-GLs) through the stronger electrostatic attraction and hydrogen bond force, causing higher cellulase adsorption amount compared to DA-EHLR. Further exploration demonstrated that the cellobiose’s catalytic and binding sites on β-GLs were separated from the binding site of SPORL-EHLR on β-GLs, resulting in minimal inhibition of β-GLs activity when bound to SPORL-EHLR. Furthermore, adding SPORL-EHLR in SCB hydrolysis saved 40% cellulase. This study deepens the understanding of the adsorption behavior between lignin and cellulase.

Adaptive laboratory evolution under acetic acid stress enhances the multistress tolerance and ethanol production efficiency of Pichia kudriavzevii from lignocellulosic biomass

Second-generation bioethanol production using lignocellulosic biomass as feedstock requires a highly efficient multistress-tolerant yeast. This study aimed to develop a robust yeast strain of P. kudriavzevii via the adaptive laboratory evolution (ALE) technique. The parental strain of P. kudriavzevii was subjected to repetitive long-term cultivation in medium supplemented with a gradually increasing concentration of acetic acid, the major weak acid liberated during the lignocellulosic pretreatment process. Three evolved P. kudriavzevii strains, namely, PkAC-7, PkAC-8, and PkAC-9, obtained in this study exhibited significantly higher resistance toward multiple stressors, including heat, ethanol, osmotic stress, acetic acid, formic acid, furfural, 5-(hydroxymethyl) furfural (5-HMF), and vanillin. The fermentation efficiency of the evolved strains was also improved, yielding a higher ethanol concentration, productivity, and yield than the parental strain, using undetoxified sugarcane bagasse hydrolysate as feedstock. These findings provide evidence that ALE is a practical approach for increasing the multistress tolerance of P. kudriavzevii for stable and efficient second-generation bioethanol production from lignocellulosic biomass.

Sugar cane bagasse hydrolysate (SBH) as a lucrative carbon supplement to upgrade the lipid and fatty acid production in Chlorococcum sp. for biodiesel through an optimized binary solvent system

Cost is the crucial impediment in commercializing microalgal biodiesel. Therefore, cultivating microalgae in cost-effective nutrients reduces the upstream process cost remarkably. Thus, in this study, sugar cane bagasse hydrolysate (SBH) as a lucrative carbon supplement for Chlorococcum sp. and subsequent lipid extraction via an optimized solvent system for biodiesel production was investigated. Characterization of SBH revealed the presence of various monosaccharides and other sugar derivatives such as glucose, fructose, xylose, arabinose, etc. The maximum dry cell weight of 1.7 g/L was estimated in cultures grown in 10 mL SBH. Different solvents such as diethyl ether (DEE), chloroform (CHL), ethyl acetate (ETA), hexane (HEX), methanol (MET), ethanol (ETOH), acetone (ACE) and also combination of solvents (2:1 ratio) such as DEE: MET, CHL: MET, HEX: MET, HEX: ETOH was tested for lipid extraction efficacy. Among solvents used, 12.3% and 18.4% of lipids were extracted using CHL and CHL: MET, respectively, from 10 mL SBH amended cultures. However, the biodiesel yield was found to be similar at about 70.16 % in both SBH and no SBH-added cultures. The fatty acid profile of the biodiesel shows palmitic, oleic, linoleic, linolenic, and arachidonic acid as principal fatty acids. Further, the levels of SFAs, MUFAs, and PUFAs in 10 mL SBH-added cells were 24.67, 12.89, and 34.24%, respectively. Eventually, the fuel properties of Chlorococcum sp. biodiesel, satisfying international biodiesel standards, make the biodiesel a viable diesel substitute in the future.

Calcium alginate-immobilized β-glucosidase from Moniliophthora perniciosa: characterization and sugarcane bagasse hydrolysis

The utilization of lignocellulosic materials for second-generation ethanol production via enzymatic catalysts is primarily hindered by enzyme cost. Enzymatic immobilization emerges as a viable solution, enabling enzyme reuse. This study investigated the immobilization of an enzymatic extract obtained from Moniliophthora perniciosa fermentation in calcium alginate spheres using the direct trapping method. Initial tests assessed β-glucosidase activity, showing that a higher concentration of calcium chloride (1 M) alongside larger diameter spheres yielded improved results. The immobilized enzyme was reused for up to 17 cycles without significant loss of activity. The percentage of reducing sugars after 48-h hydrolysis with the supplemented enzymatic extract was 226%, doubling the value achieved with only the free enzymatic extract. The immobilized enzyme retained 50% of its initial activity after 1 h at 80 °C, demonstrating higher activity at pH 6 and 60 °C. These findings suggest that this immobilization technique is simple, economically viable, and effective for the hydrolysis of pretreated sugarcane bagasse.

Fermentative Production of β-Carotene from Sugarcane Bagasse Hydrolysate by Rhodotorula glutinis CCT-2186.

Β-Carotene is a red-orange pigment that serves as a precursor to important pharmaceutical molecules like vitamin A and retinol, making it highly significant in the industrial sector. Consequently, there is an ongoing quest for more sustainable production methods. In this study, glucose and xylose, two primary sugars derived from sugarcane bagasse (SCB), were utilized as substrates for β-carotene production by Rhodotorula glutinis CCT-2186. To achieve this, SCB underwent pretreatment using NaOH, involved different concentrations of total solids (TS) (10%, 15%, and 20%) to remove lignin. Each sample was enzymatically hydrolyzed using two substrate loadings (5% and 10%). The pretreated SCB with 10%, 15%, and 20% TS exhibited glucose hydrolysis yields (%wt) of 93.10%, 91.88%, and 90.77%, respectively. The resulting hydrolysate was employed for β-carotene production under batch fermentation. After 72h of fermentation, the SCB hydrolysate yielded a β-carotene concentration of 118.56 ± 3.01mg/L. These findings showcase the robustness of R. glutinis as a biocatalyst for converting SCB into β-carotene.

Improvement of Laccase Activity in Co-Culture of Panus lecomtei and Sporidiobolus pararoseus and Its Application as an Enzymatic Additive in Biomass Hydrolysis and Dye Decolorization

This work investigates the effects of the co-culture between the filamentous fungus Panus lecomtei and the yeast Sporidiobolus pararoseus in the production of laccases. The variations of time interval and inoculum volume of S. pararoseus in co-cultures with P. lecomtei stimulated laccase production, reaching its highest activity at nearly 2960.7 ± 244 U/mL with a maximum time point of 120 h and 2.0% (v/v), respectively. Further application in the pretreated sugarcane bagasse hydrolysis was performed, using P. lecomtei and S. pararoseus extract added to an enzyme mixture from the co-culture of P. lecomtei and Trichoderma reesei that positively favored the hydrolysis efficiency by 66.87%. Furthermore, the addition of P. lecomtei and S. pararoseus extract increased the degradation of industrial anthraquinone Remazol Brilliant Blue R by 78.98%. As a result, the extract derived from the co-culture of P. lecomtei and S. pararoseus rich in laccases presents potential in biotechnological applications, being suitable in the hydrolysis of lignocellulosic biomass and the degradation of unwanted dyes released in the environment.

Bioethanol production from mixed sugars at a semi-pilot scale through two-step repeated sequential fermentation

Assessing the industrial suitability of sequential culture for efficient conversion of mixed sugars from plant biomass hydrolysate is essential. In the present study, a two-stage sequential fermentation of mixed sugar-rich sugar cane bagasse hydrolysate was performed to produce bioethanol. In the first stage, glucose fermentation using Z. mobilis was carried out, followed by xylose fermentation using S. stipitis in the second. However, xylose fermentation was done only after completely separating primary cells and residual ethanol. Sequential fermentation of mixed sugar-rich bagasse hydrolysate yielded an ethanol titer of 77.7 g.L−1 with an average ethanol yield of 0.48 g.g−1 and overall ethanol productivity of 1.38 g.L−1.h−1. Further, repeated sequential fermentation (RSF) of mixed sugars was performed for two cycles. RSF assessed the fermentation performance of high cell density sequential culture achieved through sequential cell recycling. The maximum ethanol productivity achieved from glucose and xylose was 6.92 g.L−1.h−1 and 2.28 g.L−1.h−1, respectively. In addition, a techno-economic analysis found that the minimum selling price of the ethanol (MSP) produced from sequential fermentation of mixed sugar-rich bagasse hydrolysate (scenario I) was up to 1.7 US$. L−1. On the other hand, the MSP calculated after omitting reagent costs of synthetic glucose and xylose of the first scenario was up to 0.52 US$. L−1.

Production of Phenylacetylcarbinol via Biotransformation Using the Co-Culture of Candida tropicalis TISTR 5306 and Saccharomyces cerevisiae TISTR 5606 as the Biocatalyst.

Phenylacetylcarbinol (PAC) is a precursor for the synthesis of several pharmaceuticals, including ephedrine, pseudoephedrine, and norephedrine. PAC is commonly produced through biotransformation using microbial pyruvate decarboxylase (PDC) in the form of frozen-thawed whole cells. However, the lack of microorganisms capable of high PDC activity is the main factor in the production of PAC. In addition, researchers are also looking for ways to utilize agro-industrial residues as an inexpensive carbon source through an integrated biorefinery approach in which sugars can be utilized for bioethanol production and frozen-thawed whole cells for PAC synthesis. In the present study, Candida tropicalis, Saccharomyces cerevisiae, and the co-culture of both strains were compared for their biomass and ethanol concentrations, as well as for their volumetric and specific PDC activities when cultivated in a sugarcane bagasse (SCB) hydrolysate medium (SCBHM). The co-culture that resulted in a higher level of PAC (8.65 ± 0.08 mM) with 26.4 ± 0.9 g L-1 ethanol production was chosen for further experiments. Biomass production was scaled up to 100 L and the kinetic parameters were studied. The biomass harvested from the bioreactor was utilized as frozen-thawed whole cells for the selection of an initial pyruvate (Pyr)-to-benzaldehyde (Bz) concentration ([Pyr]/[Bz]) ratio suitable for the PAC biotransformation in a single-phase emulsion system. The initial [Pyr]/[Bz] at 100/120 mM resulted in higher PAC levels with 10.5 ± 0.2 mM when compared to 200/240 mM (8.60 ± 0.01 mM). A subsequent two-phase emulsion system with Pyr in the aqueous phase, Bz in the organic phase, and frozen-thawed whole cells of the co-culture as the biocatalyst produced a 1.46-fold higher PAC level when compared to a single-phase emulsion system. In addition, the cost analysis strategy indicated preliminary costs of USD 0.82 and 1.01/kg PAC for the single-phase and two-phase emulsion systems, respectively. The results of the present study suggested that the co-culture of C. tropicalis and S. cerevisiae can effectively produce bioethanol and PAC from SCB and would decrease the overall production cost on an industrial scale utilizing the two-phase emulsion system with the proposed multiple-pass strategy.

Utilization of Burkholderia sp. ISTR5 for enhanced saccharification and fermentation of agricultural waste for production and upgradation of biogas by calcite-based bio-composite materials

Utilization of agricultural feedstocks like Sugarcane bagasse, Mustard Husk and Rice plus tobacco Husk by Burkholderia sp. ISTR5 was evaluated under submerged culture conditions. Percent loss of feedstocks, total soluble sugar, saccharification efficiency, bacterial count and FTIR were major factors that indicated sugarcane bagasse to be the best feedstock for the production of Bio-methane as compared to other used feedstocks in the experiment. Further, biogas produced by fermentation process of sugarcane bagasse hydrolysate and fermentation was upgraded with the help of fabricated bio-mineralized product of CO2 sequestrating bacterium, Serratia sp., and biochar. The synthesis of calcite-based bio-composite materials was confirmed by FTIR, FESEM, XRD, EDX. The results indicated the usage of Bagasse was more efficient than other two feedstocks and also the usage of calcite-based bio-composite helped in the upgradation of biogas by removal of CO2 and other contaminants. The results indicated possible applications for in-situ biomethanation and clean energy.

Production of β-glucosidase by Rhodotorula oryzicola and use of enzyme for hydrolysis of sugarcane bagasse delignified.

Bioethanol is obtained by hydrolysis of sugarcane bagasse by cellulases. Commercial cellulases are expensive and have a low concentration of β-glucosidase (EC 3.2.1.21), which decrease hydrolysis efficiency. The present work aims to produce supernatant rich in β-glucosidase (BGL) using the yeast Rhodotorula oryzicola and apply it in the hydrolysis of delignified sugarcane bagasse. Yeast fermented in a modified YPD (Yeast Peptone Dextrose) medium with 0.5% (w/v) cellobiose and 1.0% (w/v) glucose produced BGL with a specific activity of 1.44 ± 0.013 U/mg. Partial purification of BGL by acetone showed a specific activity of 3.48 U/mg. The optimum pH and temperature were 6.02 and 65°C, respectively. BGL partially purified (BGLppR.oryzicola) by acetone showed tolerance to glucose, with a relative activity of 82.89 ± 0.11%. The activity increased with the addition of iron sulfate and zinc sulfate and decreased with manganese sulfate. BGL partially purified was thermal stable, with a relative activity of 85.59% after 60min at 90°C. BGL partially purified applied in the hydrolysis of sugarcane bagasse delignified with 3% (w/w) NaOH + 6% (w/w) Na2SO3 showed a conversion rate of 72.46 ± 1.60%. The results showed that BGL partially purified is a glucose tolerant cellulase of low-cost, promising the application of bioethanol production.

Bioacetoin Production by Bacillus subtilis subsp. subtilis Using Enzymatic Hydrolysate of Lignocellulosic Biomass

Acetoin is an important bio-product useful in the chemical, food and pharmaceutical industries. Microbial fermentation is the major process for the production of bioacetoin, as the petroleum resources used in chemical methods are depleting day by day. Bioacetoin production using wild microorganisms is an easy, eco-friendly and economical method for the production of bioacetoin. In the present study, culture conditions and nutritional requirements were optimized for bioacetoin production by a wild and non-pathogenic strain of B. subtilis subsp. subtilis JJBS250. The bacterial culture produced maximum bioacetoin (259 mg L−1) using peptone (3%) and sucrose (2%) at 30 °C, 150 rpm and pH 7.0 after 24 h. Further supplementation of combinatorial nitrogen sources, i.e., peptone (1%) and urea (0.5%), resulted in enhanced titre of bioacetoin (1017 mg L−1) by the bacterial culture. An approximately 46.22–fold improvement in bioacetoin production was achieved after the optimization process. The analysis of samples using thin layer chromatography confirmed the presence of bioacetoin in the culture filtrate. The enzymatic hydrolysate was obtained by saccharification of pretreated rice straw and sugarcane bagasse using cellulase from Myceliophthora thermophila. Fermentation of the enzymatic hydrolysate (3%) of pretreated rice straw and sugarcane bagasse by the bacterial culture resulted in 210 and 473.17 mgL−1 bioacetoin, respectively. Enzymatic hydrolysates supplemented with peptone as a nitrogen source showed a two to four-fold improvement in the production of bioacetoin. Results have demonstrated the utility of wild type B. subtilis subsp. subtilis JJBS250 as a potential source for economical bioacetoin production by making use of renewable and cost-effective lignocellulosic substrate. Therefore, this study will help in the sustainable management of agricultural waste for the industrial production of bioacetoin, and in combating environmental pollution.

A Novel Kinetic Modeling of Enzymatic Hydrolysis of Sugarcane Bagasse Pretreated by Hydrothermal and Organosolv Processes.

Lignocellulosic biomasses have a complex and compact structure, requiring physical and/or chemical pretreatments to produce glucose before hydrolysis. Mathematical modeling of enzymatic hydrolysis highlights the interactions between cellulases and cellulose, evaluating the factors contributing to reactor scale-up and conversion rates. Furthermore, this study evaluated the influence of two pretreatments (hydrothermal and organosolv) on the kinetics of enzymatic hydrolysis of sugarcane bagasse. The kinetic parameters of the model were estimated using the Pikaia genetic algorithm with data from the experimental profiles of cellulose, cellobiose, glucose, and xylose. The model considered the phenomenon of non-productive adsorption of cellulase on lignin and inhibition of cellulase by xylose. Moreover, it included the behavior of cellulase adsorption on the substrate throughout hydrolysis and kinetic equations for obtaining xylose from xylanase-catalyzed hydrolysis of xylan. The model for both pretreatments was experimentally validated with bagasse concentration at 10% w/v. The Plackett-Burman design identified 17 kinetic parameters as significant in the behavior of process variables. In this way, the modeling and parameter estimation methodology obtained a good fit from the experimental data and a more comprehensive model.

Hydrolysate production from sugarcane bagasse using steam explosion and sequential steam explosion-dilute acid pretreatment for polyhydroxyalkanoate fermentation

Polyhydroxyalkanoates (PHAs) are potential alternatives to conventional petroleum-based plastics. One of the barriers to the commercialization of PHAs is its high production cost, which is primarily due to substrate. Agricultural lignocellulosic residues, such as sugarcane bagasse, can be used as substrates to lower production costs. In order to effectively convert the substrate to PHA, sugarcane bagasse must be pretreated. In this study, steam explosion and sequential steam explosion–dilute H2SO4 pretreatment of sugarcane bagasse were optimized to effectively release reducing sugars through enzymatic hydrolysis. Experiments using response surface methodology (RSM) revealed that steam temperature had the greatest influence on lowering sugar content for both sequential and steam explosion pretreatments. The optimum steam explosion conditions were 230 °C steam temperature and 701 s holding time. The concentration of reducing sugars in the enzymatic hydrolysate produced by the hydrolysis of steam-exploded sugarcane bagasse was 6.91 g/L (46.07% yield). On the other hand, the optimum conditions for sequential pretreatment were 230 °C steam explosion temperature, 137 °C dilute acid temperature, 42 min of dilute acid reaction time, and 4.75% w/v H2SO4 concentration, resulting in a hydrolysate with a reducing sugar content of 12.89 g/L (85.93% yield). When steam explosion and diluted H2SO4 pretreatment were combined, a yield increase of reducing sugar of 87% was observed. PHA in the form of polyhydroxybutyrate (PHB) was successfully synthesized using the hydrolysate through bacterial fermentation, with a concentration of 1.99 g/L (16.79% yield) after 24 h. As a result, sequential pretreatment was effective in producing enzymatic hydrolysates from sugarcane bagasse that could be utilized to produce PHA.

Separation and characterisation of glyceryl glycosides and lignin from acid-catalysed glycerol pretreatment hydrolysate of sugarcane bagasse

Acid-catalysed glycerol (ACG) pretreatment of biomass is one of the pre-treating techniques for the enzyme-mediated lignocellulosic biorefinery, while inadequate attention has been paid to the glycerol modified saccharides and lignin redistributed to the hydrolysate, nor their bioactive properties. In this study, a sequential process involving tetrahydrofuran (THF) extraction and carbon/celite adsorption-elution was employed to recover lignin and glyceryl glycosides (GG) from ACG hydrolysate. The physicochemical and structural properties of lignin were systematically explored, and were related to their antioxidation properties, the composition and moisturising activities of GG was investigated. Two types of lignin i.e., water-insoluble lignin (WIL) and water-soluble lignin (WSL) were obtained, accounting for 49.60 wt% and 38.00 wt% of the total lignin in raw bagasse, respectively. GG separated from the hydrolysate yielded an overall recovery of 68.17 wt% of the xylan from the raw bagasse. The relatively high yield of lignin and GG can be attributed to the incorporation of glycerol molecules. 2D HSQC NMR results revealed that glycerol effectively preserved the β-O-4 structure of lignin during ACG pretreatment through α-etherification and γ-esterification. 31P NMR results showed that WSL has more aliphatic hydroxyl groups, resulting in increased water solubility, whereas WIL exhibited a higher amount of phenolic hydroxyl groups, contributing to the increased in vitro antioxidant properties. WSL contained significant proportion of p-coumaric acid glycerides and demonstrated low cytotoxicity along with a favorable cellular antioxidant capacity (CAA). HPLC-MS analysis revealed that the GG was a mixture of 56.44% glyceryl xylosides and 36.49% glyceryl glucosides, which displayed a superior moisturising capacity compared to commercial humectants such as hyaluronic acid (HA) and α-glyceryl glucosides (αGG). Overall, this study establishes a foundation for the extraction of value-adding bioactive compounds from acid-catalysed glycerol pretreatment hydrolysate, supporting the implementation of ACG techniques in biorefineries.

Saccharification of sugarcane bagasse using cellulases and oxidoreductases enzymes

Lignin is the major polymer responsible for limiting the rates of lignocellulose degradation. Enzymatic hydrolysis of lignin (using oxidorreductases enzymes) open the way to action of cellulose and hemicellulose -degrading enzymes systems to obtain a fermentable hydrolysate rich in monomeric compounds from the carbohydrate polymers present in the biomass. Trichoderma reesei is an important fungus that is widely used as a source of cellulases for the hydrolysis of plant cell wall polysaccharides. In this study, was identified the filamentous fungi Pestalotiopsis sp BBF245, as a promising strain for production of oxidoreductases enzymes. Enzyme cocktails were composed, using cellulases from T. reesei and oxidoreductases enzymes from Pestalotiopsis sp BBF245 for hydrolysis of sugarcane bagasse (SCB) in natura. The amounts of reducing sugars released from the saccharification of bagasse was of 15,52 g/L after 24 hours of incubation. The results show that the combination of lignocellulose-degrading enzymes significantly increased the degradation of sugarcane bagasse and suggest that the use of enzyme cocktails oxidoreductases and cellulases may significantly improve the hydrolysis of biomass.