Research

16 pages, 3693 KiB

Open AccessArticle

Application of Aromatic Ring Quaternary Ammonium and Phosphonium Salts–Carboxylic Acids-Based Deep Eutectic Solvent for Enhanced Sugarcane Bagasse Pretreatment, Enzymatic Hydrolysis, and Cellulosic Ethanol Production

by Biying Li, Ziqi Qiu, Jiale Huang, Xiaoling Xian, Xiaojie Zheng and Xiaoqing Lin

Fermentation 2023, 9(11), 981; https://doi.org/10.3390/fermentation9110981 - 16 Nov 2023

Viewed by 1166

Abstract

Deep eutectic solvents (DESs) with a hydrophobic aromatic ring structure offer a promising pretreatment method for the selective delignification of lignocellulosic biomass, thereby enhancing enzymatic hydrolysis. Further investigation is needed to determine whether the increased presence of aromatic rings in hydrogen bond receptors [...] Read more.

Deep eutectic solvents (DESs) with a hydrophobic aromatic ring structure offer a promising pretreatment method for the selective delignification of lignocellulosic biomass, thereby enhancing enzymatic hydrolysis. Further investigation is needed to determine whether the increased presence of aromatic rings in hydrogen bond receptors leads to a more pronounced enhancement of lignin removal. In this study, six DES systems were prepared using lactic acid (LA)/acetic acid (AA)/levulinic acid (LEA) as hydrogen bond donors (HBD), along with two independent hydrogen bond acceptors (HBA) (benzyl triethyl ammonium chloride (TEBAC)/benzyl triphenyl phosphonium chloride (BPP)) to evaluate their ability to break down sugarcane bagasse (SCB). The pretreatment of the SCB (raw material) was carried out with the above DESs at 120 °C for 90 min with a solid–liquid ratio of 1:15. The results indicated that an increase in the number of aromatic rings may result in steric hindrance during DES pretreatment, potentially diminishing the efficacy of delignification. Notably, the use of the TEBAC:LA-based DES under mild operating conditions proved highly efficient in lignin removal, achieving 85.33 ± 0.52% for lignin removal and 98.67 ± 2.84% for cellulose recovery, respectively. The maximum digestibilities of glucan (56.85 ± 0.73%) and xylan (66.41 ± 3.06%) were attained after TEBAC:LA pretreatment. Furthermore, the maximum ethanol concentration and productivity attained from TEBAC:LA-based DES-pretreated SCB were 24.50 g/L and 0.68 g/(L·h), respectively. Finally, the comprehensive structural analyses of SCB, employing X-rays, FT-IR, and SEM techniques, provided valuable insights into the deconstruction process facilitated by different combinations of HBDs and HBAs within the DES pretreatment. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)

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20 pages, 4136 KiB

Open AccessArticle

Using Dielectric Constant Measurement to Monitor Ethanol Fermentation and Anaerobic Co-Digestion of Lignocellulosic Biomass

by Zoltán Péter Jákói, Balázs Lemmer, Réka Dobozi, Cecilia Hodúr and Sándor Beszédes

Fermentation 2023, 9(10), 902; https://doi.org/10.3390/fermentation9100902 - 10 Oct 2023

Viewed by 1012

Abstract

Our study aimed to investigate the applicability of dielectric measurements across three key stages of plant-based biomass utilization: enzymatic hydrolysis of native and microwave pre-processed corn-cob residues, ethanol fermentation of the hydrolysates, and anaerobic co-digestion with meat-industry wastewater sludge. Our major findings reveal [...] Read more.

Our study aimed to investigate the applicability of dielectric measurements across three key stages of plant-based biomass utilization: enzymatic hydrolysis of native and microwave pre-processed corn-cob residues, ethanol fermentation of the hydrolysates, and anaerobic co-digestion with meat-industry wastewater sludge. Our major findings reveal that microwave pre-treatment not only accelerates enzymatic hydrolysis but also improves sugar yield. A strong linear correlation (r = 0.987–0.979; R² = 0.974–0.978) was observed between the dielectric constant and sugar concentrations, offering a reliable monitoring mechanism. During ethanol fermentation, microwave pre-treated samples resulted in higher yields; however, the overall bioconversion efficiency was lower. Dielectric measurements also exhibited a strong linear correlation (r = 0.989–0.997; R² = 0.979–0.993) with ethanol concentration. Finally, anaerobic co-digestion could be effectively monitored through the measurement of the dielectric constants (r = 0.981–0.996; R² = 0.963–0.993), with microwave-treated samples showing higher biogas yields. These results demonstrate that dielectric measurements provide a promising alternative for monitoring and controlling biomass utilization processes. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)

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11 pages, 1988 KiB

Open AccessArticle

Cloning and Characterization of Cellulase from Paenibacillus peoriae MK1 Isolated from Soil

by Sang Jin Kim, Kyung-Chul Shin, Dae Wook Kim, Yeong-Su Kim and Chang-Su Park

Fermentation 2023, 9(10), 873; https://doi.org/10.3390/fermentation9100873 - 27 Sep 2023

Viewed by 1109

Abstract

An isolated bacterium from soil that highly hydrolyzes cellulose was identified as Paenibacillus peoriae and named P. peoriae MK1. The cellulase from P. peoriae MK1 was cloned and expressed in Escherichia coli. The purified recombinant cellulase, a soluble protein with 13.2-fold purification [...] Read more.

An isolated bacterium from soil that highly hydrolyzes cellulose was identified as Paenibacillus peoriae and named P. peoriae MK1. The cellulase from P. peoriae MK1 was cloned and expressed in Escherichia coli. The purified recombinant cellulase, a soluble protein with 13.2-fold purification and 19% final yield, displayed a specific activity of 77 U/mg for CM-cellulose and existed as a metal-independent monomer of 65 kDa. The enzyme exhibited maximum activity at pH 5.0 and 40 °C with a half-life of 9.5 h in the presence of Ca²⁺ ion. The highest activity was observed toward CM-cellulose as an amorphous substrate, followed by swollen cellulose, and sigmacell cellulose and α-cellulose as crystalline substrates. The enzyme and substrate concentrations for the hydrolysis of CM-cellulose were optimized to 133 U/mL and 20 g/L CM-cellulose, respectively. Under these conditions, CM-cellulose was hydrolyzed to reducing sugars composed mostly of oligosaccharides by cellulase from P. peoriae MK1 as an endo-type cellulase with a productivity of 11.1 g/L/h for 10 min. Our findings will contribute to the industrial usability of cellulase and the research for securing cellulase sources. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)

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14 pages, 4507 KiB

Open AccessArticle

Evaluation of the Enzymatic Production and Prebiotic Activity of Galactomannan Oligosaccharides Derived from Gleditsia microphylla

by Hanghong Wang, Chenhuan Lai, Yuheng Tao, Mengyi Zhou, Ruilin Tang and Qiang Yong

Fermentation 2023, 9(7), 632; https://doi.org/10.3390/fermentation9070632 - 04 Jul 2023

Cited by 3 | Viewed by 1003

Abstract

Oligosaccharides have received considerable attention as prebiotics because they exhibit potential health benefits related to their ability to modulate intestinal bacterial composition. This study evaluated the effects of galactomannan oligosaccharides (GMOS) derived from Gleditsia microphylla as a prebiotic on human intestinal bacteria. The [...] Read more.

Oligosaccharides have received considerable attention as prebiotics because they exhibit potential health benefits related to their ability to modulate intestinal bacterial composition. This study evaluated the effects of galactomannan oligosaccharides (GMOS) derived from Gleditsia microphylla as a prebiotic on human intestinal bacteria. The β-mannanase used for the enzymatic hydrolysis of GMOS was produced by Trichoderma reesei Rut C-30. The enzymatic hydrolysis of GMOS was found to occur under optimal conditions at 50 °C, pH 5, 20 U/g-GM, and 20 g/L, and resulted in a yield of 70.78% ± 1.34%. The purity of GMOS after purification was 81.50%. Upon performing in vitro human fecal fermentation using GMOS as a carbon source, it was observed that GMOS effectively promoted the proliferation of intestinal bacteria, and the utilization efficiency of GMOS by intestinal bacteria was found to be at 98.40%. In addition, GMOS were found to have a stabilizing effect on intestinal pH. Additionally, 16S rRNA sequencing of GMOS revealed that GMOS significantly affected the diversity of gut microbiota. Specifically, GMOS exhibited a significant inhibitory effect on Fusobacteria at the phyla and genus level, and demonstrated a significant inhibitory effect on Fusobacterium. Moreover, the results for the prediction of metabolic function analysis showed that GMOS had a significant effect on the level two metabolism of carbohydrates, cofactors, and vitamins. Furthermore, during level three metabolism, the lipoic acid metabolism was significantly affected by GMOS. These results provide a theoretical basis for the potential use of galactomannan oligosaccharides from Gleditsia microphylla as prebiotics for regulating human intestinal bacteria. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)

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15 pages, 2282 KiB

Open AccessArticle

Two-Step Hydrothermal Pretreatments for Co-Producing Xylooligosaccharides and Humic-like Acid from Vinegar Residue

by Ningxin Jiao, Yuanyuan Zhu, Haoran Li, Yongjian Yu, Yong Xu and Junjun Zhu

Fermentation 2023, 9(7), 589; https://doi.org/10.3390/fermentation9070589 - 24 Jun 2023

Cited by 3 | Viewed by 917

Abstract

This study proposes an efficient strategy for co-producing high-value-added xylooligosaccharides (XOS) and humic-like acid (HLA) from vinegar residue based on two-step hydrothermal pretreatments. During the first-step hydrothermal pretreatment (170 °C, 50 min), 29.1% of XOS (X₂-X₆) was obtained. The [...] Read more.

This study proposes an efficient strategy for co-producing high-value-added xylooligosaccharides (XOS) and humic-like acid (HLA) from vinegar residue based on two-step hydrothermal pretreatments. During the first-step hydrothermal pretreatment (170 °C, 50 min), 29.1% of XOS (X₂-X₆) was obtained. The XOS yield was further improved to 36.2% with endoxylanase hydrolysis, thereby increasing the value of (X₂-X₄)/XOS from 0.8 to 1.0. Subsequently, the second-step hydrothermal pretreatment was investigated to produce HLA from the solid residue of the first-step hydrothermal pretreatment. The highest HLA yield was 15.3% in the presence of 0.6 mol/L of KOH at 210 °C for 13 h. In addition, 31.7% of hydrochar by-product was obtained. The mass balance results showed that 1000 g of vinegar residue produced 67.9 g of XOS, 91.6 g of HLA, and 189.5 g of hydrochar. Therefore, this study provides a promising pathway for comprehensive use of lignocellulosic biomass in producing XOS and HLA. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)

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14 pages, 1513 KiB

Open AccessArticle

Delignification of Halophyte Atriplex crassifolia by Green Recyclable Deep Eutectic Solvents for Enhanced Production of Biogas

by Ali Nawaz, Rida Chaudhary, Ikram Ul Haq, Xiaoliang Fu, Rong Huang, Hamid Mukhtar and Kankan Jiang

Fermentation 2023, 9(3), 314; https://doi.org/10.3390/fermentation9030314 - 22 Mar 2023

Cited by 1 | Viewed by 1309

Abstract

Deep eutectic solvents (DESs) have upgraded the practices of valorizing lignocellulosic feedstock by lessening biomass recalcitrance through delignification in precise and economical manner. In this study, the influence of a series of deep eutectic mixtures was evaluated on the halophyte Atriplex crassifolia for [...] Read more.

Deep eutectic solvents (DESs) have upgraded the practices of valorizing lignocellulosic feedstock by lessening biomass recalcitrance through delignification in precise and economical manner. In this study, the influence of a series of deep eutectic mixtures was evaluated on the halophyte Atriplex crassifolia for achieving elevated biogas production. Initially, the biomass was pretreated via several DESs with varying hydrogen bond donors (HBDs) including carboxylic acids, amine/amide, and polyols/glycols. DES composed of choline chloride (ChCl) and lactic acid (LA) evidenced as the most effective solvent in achieving high lignin removal rates and was further optimized by evaluating the parameters of molar ratio of DES components, solid-to-liquid ratio, and solvent addition. A maximum delignification value of 89.5% was achieved by 15% diluted ChCl: LA (1:2) DES at a biomass loading of 1:15. The solubilization rate of diluted ChCl: LA was also raised up to 38%. FT-IR analysis revealed significant lignin elimination from ChCl: LA pretreated substrates. Moreover, ≥88% of ChCl: LA DES was recovered after up to three pretreatment cycles, retaining ≥85% delignification efficiency. Fresh DES-pretreated Atriplex crassifolia recorded 32.2 mL/g of biogas production yield due to increased cellulosic content. The findings validated Atriplex crassifolia as an efficient feedstock for biogas production and confirmed the affectivity of ChCl: LA pretreatment in eliminating the lignin barrier, ultimately making cellulosic sugars readily biodegradable and highly accessible for anaerobic microorganisms. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)

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11 pages, 2639 KiB

Open AccessArticle

Identification of a Novel Dehydrogenase from Gluconobacter oxydans for Degradation of Inhibitors Derived from Lignocellulosic Biomass

by Hongsen Zhang, Jiahui Jiang, Conghui Quan, Guizhong Zhao, Guotao Mao, Hui Xie, Fengqin Wang, Zhimin Wang, Jian Zhang, Pingping Zhou and Andong Song

Fermentation 2023, 9(3), 286; https://doi.org/10.3390/fermentation9030286 - 15 Mar 2023

Viewed by 1273

Abstract

Inhibitors from lignocellulosic biomass have become the bottleneck of biorefinery development. Gluconobacter oxydans DSM2003 showed a high performance of inhibitors degradation, which had a short lag time in non-detoxified corn stover hydrolysate and could convert 90% of aldehyde inhibitors to weaker toxic acids. [...] Read more.

Inhibitors from lignocellulosic biomass have become the bottleneck of biorefinery development. Gluconobacter oxydans DSM2003 showed a high performance of inhibitors degradation, which had a short lag time in non-detoxified corn stover hydrolysate and could convert 90% of aldehyde inhibitors to weaker toxic acids. In this study, an aldehyde dehydrogenase gene W826-RS0111485, which plays an important function in the conversion of aldehyde inhibitors in Gluconobacter oxydans DSM2003, was identified. W826-RS0111485 was found by protein profiling, then a series of enzymatic properties were determined and were heterologously expressed in E. coli. The results indicated that NADP is the most suitable cofactor of the enzyme when aldehyde inhibitor is the substrate, and it had the highest oxidation activity to furfural among several aldehyde inhibitors. Under the optimal reaction conditions (50 °C, pH 7.5), the Km and Vmax of the enzyme under furfural stress were 2.45 and 80.97, respectively, and the Kcat was 232.22 min⁻¹. The biodetoxification performance experiments showed that the recombinant E. coli containing the target gene completely converted 1 g/L furfural to furoic acid within 8 h, while the control E. coli only converted 18% furfural within 8 h. It was further demonstrated that W826-RS0111485 played an important role in the detoxification of furfural. The mining of this inhibitor degradation gene could provide a theoretical basis for rational modification of industrial strains to enhance its capacity of inhibitor degradation in the future. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)

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12 pages, 1379 KiB

Open AccessArticle

Low pH Stress Enhances Gluconic Acid Accumulation with Enzymatic Hydrolysate as Feedstock Using Gluconobacter oxydans

by Lin Dai, Zhina Lian, Yixiu Fu, Xin Zhou, Yong Xu, Xuelian Zhou, Boris N. Kuznetsov and Kankan Jiang

Fermentation 2023, 9(3), 278; https://doi.org/10.3390/fermentation9030278 - 12 Mar 2023

Cited by 4 | Viewed by 2686

Abstract

Gluconic acid has been increasingly in demand in recent years due to the wide applications in the food, healthcare and construction industries. Plant-derived biomass is rich in biopolymers that comprise glucose as the monomeric unit, which provide abundant feedstock for gluconic acid production. [...] Read more.

Gluconic acid has been increasingly in demand in recent years due to the wide applications in the food, healthcare and construction industries. Plant-derived biomass is rich in biopolymers that comprise glucose as the monomeric unit, which provide abundant feedstock for gluconic acid production. Gluconobacter oxydans can rapidly and incompletely oxidize glucose to gluconic acid and it is regarded as ideal industrial microorganism. Once glucose is depleted, the gluconic acid will be further bio-oxidized to 2-ketogluconic acid by Gluconobacter oxydans. The endpoint is difficult to be controlled, especially in an industrial fermentation process. In this study, it was found that the low pH environment (2.5~3.5) could limit the further metabolism of gluconic acid and that it resulted in a yield over 95%. Therefore, the low pH stress strategy for efficiently producing gluconic acid from biomass-derived glucose was put forward and investigated with enzymatic hydrolysate. As a result, 98.8 g/L gluconic acid with a yield of 96% could be obtained from concentrated corncob enzymatic hydrolysate that initially contained 100 g/L glucose with 1.4 g/L cells loading of Gluconobacter oxydans. In addition, the low pH stress strategy could effectively control end-point and decrease the risk of microbial contamination. Overall, this strategy provides a potential for industrial gluconic acid production from lignocellulosic materials. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)

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13 pages, 1878 KiB

Open AccessArticle

Influence of Heat Treatment and Solid-State Fermentation on the Lignocellulosic Fractions of Substrates Supporting Lentinula edodes (Berk.) Pegler Cultivation: Implications for Commercial Production

by Sudheer Kumar Annepu, Ved Prakash Sharma, Anupam Barh, Shwet Kamal, Mahantesh Shirur, Satish Kumar, Rakesh Kumar Bairwa, Sachin Gupta, Moni Gupta, Upma Dutta, Baby Summuna, Dharmesh Gupta and Rajnish Kumar

Fermentation 2023, 9(2), 130; https://doi.org/10.3390/fermentation9020130 - 29 Jan 2023

Cited by 2 | Viewed by 1634

Abstract

Mushroom production in India has registered a considerable growth in the recent times. However, cultivation of shiitake mushroom, which represents a major share at a global level, is still at a primitive stage in the Indian subcontinent. The scarcity of raw materials and [...] Read more.

Mushroom production in India has registered a considerable growth in the recent times. However, cultivation of shiitake mushroom, which represents a major share at a global level, is still at a primitive stage in the Indian subcontinent. The scarcity of raw materials and the cost of energy for substrate sterilization are the major hurdles for a large-scale production. The present study delves into the possibility of growing shiitake mushroom on lignocellulosic biomass (saw dust and wheat straw) processed with different heat treatments to develop a cost-effective production technology. Six different strains of shiitake mushroom, viz., DMRO-35, 51, 297, 388s, 410, 412, were used in this study. The substrates were exposed to a pasteurization temperature of 80 ± 5 °C in a bulk pasteurization chamber for three different times (H₁–H₃) and also to a high-pressure sterilization (H₄) in an autoclave. DMRO-388s was found to be the most productive strain, irrespective of the substrate and heat treatment method used. Significant differences were observed in the biological yield depending on the type of substrate and heat treatment. Changes in the biochemical composition of the lignocellulosic residues in three different stages, viz., pre heat treatment, inoculation and primordial formation stages, were recorded. Changes in heat treatment levels and duration significantly altered the cellulose/lignin ratio of the growing substrate. High-pressure sterilization aided the rapid degradation of lignin in the substrate and increased its bioavailability, thereby facilitating the fungus achieving its potential yield. A significant correlation in the positive direction between the yield levels of the tested strains and the consumption of lignin in the growing substrate was found, suggesting the significance of pre heat treatment for the bioconversion of lignin and its subsequent utilization in the solid-state fermentation process. The substrate pre heat treatment under high-pressure sterilization was proved to be beneficial to obtain the maximum yields of shiitake mushroom. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)

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12 pages, 2897 KiB

Open AccessArticle

Efficient Co-Production of Xylooligosaccharides and Glucose from Vinegar Residue by Biphasic Phenoxyethanol-Maleic Acid Pretreatment

by Yuanyuan Zhu, Ruijun Tang, Yongjian Yu, Zhen Yu, Ke Wang, Yuqin Wang, Peng Liu and Dong Han

Fermentation 2023, 9(1), 61; https://doi.org/10.3390/fermentation9010061 - 11 Jan 2023

Cited by 5 | Viewed by 1522

Abstract

A new biphasic organic solvent, phenoxyethanol-maleic acid, was carried out to pretreat and fractionate vinegar residue into glucan, xylan and lignin under mild conditions. Additional effects of key factors, temperature and phenoxyethanol concentration, on vinegar residue, were evaluated. Under the biphasic system (0.5% [...] Read more.

A new biphasic organic solvent, phenoxyethanol-maleic acid, was carried out to pretreat and fractionate vinegar residue into glucan, xylan and lignin under mild conditions. Additional effects of key factors, temperature and phenoxyethanol concentration, on vinegar residue, were evaluated. Under the biphasic system (0.5% maleic acid, 60% phenoxyethanol), 140 °C cooking vinegar residue for 1 h, 80.91% of cellulose retention in solid residue, 75.44% of hemicellulose removal and 69.28% of lignin removal were obtained. Optimal identified conditions resulted in maximum XOS of 47.3%. Then, the solid residue was enzymatically digested with a glucose yield of 82.67% at 72 h with the addition of 2.5 g/L bovine serum albumin. Finally, the residue was characterized by SEM, FTIR, XRD and BET analysis. This work demonstrated the phenoxyethanol-maleic acid pretreatment yielded XOS, fermentable sugar, and lignin with high processibility. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)

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