Data-driven interpretable analysis for polysaccharide yield prediction

Cornstalks show promise as a raw material for polysaccharide production through xylanase. Rapid and accurate prediction of polysaccharide yield can facilitate process optimization, eliminating the need for extensive experimentation in actual production to refine reaction conditions, thereby saving time and costs. However, the intricate interplay of enzymatic factors poses challenges in predicting and optimizing polysaccharide yield accurately. Here, we introduce an innovative data-driven approach leveraging multiple artificial intelligence techniques to enhance polysaccharide production. We propose a machine learning framework to identify highly accurate polysaccharide yield prediction modeling methods and uncover optimal enzymatic parameter combinations. Notably, Random Forest (RF) and eXtreme Gradient Boost (XGB) demonstrate robust performance, achieving prediction accuracies of 93.0% and 95.6%, respectively, while an independently developed deep neural network (DNN) model achieves 91.1% accuracy. A feature importance analysis of XGB reveals the enzyme solution volume's dominant role (43.7%), followed by time (20.7%), substrate concentration (15%), temperature (15%), and pH (5.6%). Further interpretability analysis unveils complex parameter interactions and potential optimization strategies. This data-driven approach, incorporating machine learning, deep learning, and interpretable analysis, offers a viable pathway for polysaccharide yield prediction and the potential recovery of various agricultural residues.

The efficient solution to decline the greenhouses emission and enrich the bacterial community during pig manure composting: Regulating the particle size of cornstalk

In present study, four lengths of chopped cornstalks were amended with pig manure respectively for 100 days aerobic fermentation, which aimed to evaluate the impact of different length of agricultural solid wastes on gaseous emission and dominating bacterial community succession and connection. The result revealed that the maximum ammonia volatilization was observed in 5 cm of straw samples attributed to the prominent mineralization, which was opposite to the emission of CH4 and N2O. As for global warming potential, the minimum value was detected in 5 cm of straw samples, which decreased by 5.03-24.75% compared with other samples. Additionally, the strongest correlation and complexity of bacterial community could be detected in 5 cm of straw treatment, representing the most vigorous bacterial metabolic ability could be recorded by optimizing the microbial habitat. Therefore, in order to decline the greenhouse effect in livestock manure composting, the 5 cm of corn straw was recommended.

Multi-omics analysis provides insight into the phytotoxicity of chicken manure and cornstalk on seed germination

To minimize environmental risks and the phytotoxic influence of organic materials on crop growth, it is necessary to test their phytotoxicity and maturity when they were used in farmland. However, the stress response of seed germination to chicken manure and cornstalks is not clear. This study used multi-omics analysis to investigate the inhibition mechanism of seed germination by chicken manure and cornstalk. Chicken manure caused destructive inhibition of seed germination with higher phytotoxicity (GI = 0). Cornstalk also had a low GI (8.81 %), while it mainly inhibited radicle growth (RL = 9.39 %) rather than seed germination (GR = 93.33 %). The response of radish seed germination to chicken manure and cornstalk phytotoxic stresses was accompanied by metabolic adjustments of storage substance accumulation, antioxidant enzyme activity change, phytohormone induction, and expression of specific proteins and gene regulation. Combined transcriptomic and proteomic analysis revealed that differential expression of 13,090 (5944 upregulated/7146 downregulated) and 3850 (2389 upregulated/1461 downregulated) genes (DEGs), and 1041 (82 upregulated/932 downregulated) and 575 (111 upregulated/464 downregulated) proteins (DEPs) at chicken manure and cornstalk treatment, respectively. Most down-regulated genes and proteins were involved in phenylpropanoid biosynthesis under chicken manure stress, which caused irreversible inhibition of seed germination. Down-regulation of phytohormone signal transduction-related genes under cornstalk stress resulted in inhibition of radicle growth, but the inhibitory stress was restorable. These findings provide new insight into the phytotoxicity of livestock manure and cornstalk on seed germination.

Effects of further composting black soldier fly larvae manure on toxic metals and resistant bacteria communities by cornstalk amendment

Rapid composting by black soldier fly larvae (BSFL) may be insufficient to maturation and humification of composting and further composting is necessary. The purpose of this study was to explore cornstalk addition on toxic metals (Cu, Zn, Pb and Cd), toxic metals resistance bacterial (TMRB) destiny and their relationship with physicochemical factors during BSFL manure composting. High-throughput sequencing was performed by six treatments, namely T1 to T6, where T1 to T3 were BSFL manures from chicken, pig and dairy manure, respectively, and T4 to T6 were same manures and utilized cornstalk to adjust C/N to 25. The results showed that cornstalk amendment could enhance the toxic metals immobilization rate compared to control treatments in the ultimate product. TMRB indicated that the major potential hosts bacteria were Firmicutes, Bacteroidota, Proteobacteria, Acidobacteriota and Actinobacteriota, and the sum relative abundance were 63.33%, 90.62%, 83.62%, 69.38%, 50.66% and 90.52% in T1 to T6 at the end of composting. Bacteria diversity and heat map revealed composting micro-ecology with additive cornstalk to remarkably effect main resistant bacterial distribution via adjusting environmental factors and potential hosts bacterial. Finally, T5 treatment was able to greatly decrease the TMRB abundance, and improve the ability of composting and ultimate product quality.

The biological and abiotic effects of powdered activated carbon on the anaerobic digestion performance of cornstalk

To comprehensively evaluate the biological and abiotic influence of powdered activated carbon (PAC) on the anaerobic digestion of cornstalk, mesophilic and thermophilic digestion were conducted. Adding PAC (10 g/L) under thermophilic system obtained the maximum cellulose degradation rate and methane yield (MY), which were 57.47% and 128.19 L/kg VS. However, adding same dose of PAC at mesophilic system decreased the MY by 8.16% while increased the cellulose degradation rate and methane production rate by 6.48% and 17.92%. Under mesophilic conditions, the enhancement of PAC was owing to the enrichment of cellulolytic microorganisms, improvement of the syntrophic process and direct interspecies electron transfer. The lower methane yield was attributed to the adsorption of carbon source by PAC and CH₄ consumption by Norank_c_Bathyarchaeia. The good performance of thermophilic system was owing to the lower adsorption capability of PAC, absence of Norank_c_Bathyarchaeia, and concentrated carbon flow to methane.

Evaluation of cornstalk as bulking agent on greenhouse gases emission and bacterial community during further composting

The aim of current work was to explore the impact of Cornstalk (CS) on greenhouse gaseous emission and maturation during further composting and analyzed its impact on bacterial diversity. Three kinds of immature fertilizers were collected from chicken, pig and dairy manure namely T1, T2 and T3 as control, T4, T5 and T6 were added CS into T1 to T3 and adjusted C/N to 25 namely treatment. The results illustrated that gases (N₂O, CH₄ and NH₃) emission of CS added treatments decreased by 6.39%-24.68%, 10.60%-23.23% and 13.00%-19.58%, respectively. But the CS amendment increased CO₂ emission by 15.53%-30.81%. The mineralization of carbon and nitrogen was mainly correlated to Firmicutes, Actinobacteria, Proteobacteria and Bacteroidota, CS amendment increased abundance by 22.28%, 17.79%, 1.48% and 35.90%, respectively. The strategy of employing CS would be the most feasible approach for recycling of immature manure, considering its compost quality and environmental from farm.

The synergistic effect of rumen cellulolytic bacteria and activated carbon on thermophilic digestion of cornstalk

To explore the bioaugmentation of rumen cellulolytic bacteria (RCB) and activated carbon (AC) on thermophilic digestion of cornstalk, biochemical methane potential tests were carried out. Adding RCB or AC can improve methane production, while simultaneous existence of AC (10 g/L) and RCB (5%) obtained the best performance. The maximum cellulose degradation rate, methane production rate and methane yield were 66.92%, 32.2 L/(kgVS·d), and 144.9 L/kgVS, which increased by 30.23%, 51.17%, and 20.35% compared with control group. The cellulolytic and fermentative bacteria (Hydrogenispora), syntrophic acetate-oxidizing bacteria (norank_o_MBA03), and hydrogenotrophic Methanothermobacter were crucial for thermophilic digestion of cornstalk. The enhancement of AC was due to the enrichment of Hydrogenispora and Methanothermobacter, while RCB can increase the abundance of cellulolytic bacteria (Halocella and norank_o_M55-D21) and mixotrophic Methanosarcina. The synergetic effect of AC and RCB owing to the enriched cellulolytic bacteria, the enhanced syntrophic acetate oxidation and the concentrated carbon metabolic flow to methane.

Role of residue cornstalk derived biochar for the enhanced bio-hydrogen production via simultaneous saccharification and fermentation of cornstalk

Biochar derived from residue cornstalk left after anaerobic bio-hydrogen production (RCA-biochar) was confirmed to enhance bio-hydrogen production from cornstalk hydrolysate. However, the role of RCA-biochar in simultaneous saccharification and fermentation (SSF) during bio-hydrogen production from cornstalk has not yet been revealed. This study therefore aims to fill this knowledge gap. It was observed that with the increase in RCA-biochar concentration from 0 g/L to 10.0 g/L, the maximal cumulative SSF bio-hydrogen yield varied from 24.3 ± 1.1 mL/g-substrate to 154.3 ± 3.6 mL/g substrate under varying pH values - 5.5, 6.0, 6.5, 7.0. The increasing bio-hydrogen production was observed to correlate with both RCA-biochar level and initial pH. Batch tests confirmed that the initial pH had an obvious effect an saccharification, while RCA-biochar affected anaerobic fermentation a lot. The findings revealed the role of previously unrecognized RCA-biochar in SSF bio-hydrogen production from cornstalk, which can provide an alternative approach for lignocellulosic bio-hydrogen production.

Residue cornstalk derived biochar promotes direct bio-hydrogen production from anaerobic fermentation of cornstalk

In this study, an innovative approach was proposed based on the implement of biochar derived from residue cornstalk left after anaerobic bio-hydrogen production (RCA-biochar) to improve direct bio-hydrogen production from anaerobic fermentation of cornstalk. The bio-hydrogen production potential and maximum bio-hydrogen production rate increased from 156.2 to 286.1 mL H₂/g substrate and 3.5 to 5.7 mL H₂/g substrate/h, respectively, following the added RCA-biochar increased from 2.5 to 15.0 g/L. Cornstalk chemical component analysis showed the cellulose and hemicellulose content decreased by 17.9-33.7% and 14.4-25.2%, and lignin content increased by 20.3-42.8%, respectively, after 96 h anaerobic fermentation with RCA-biochar 2.5-15.0 g/L. Further analyses revealed that RCA-biochar not only provided more specific surface area for hydrogen-producing bacteria attachment, but also promoted the cellulolytic enzyme activity, thereby resulted in increased substrate conversion to bio-hydrogen.The findings obtained in this study may provide supports for effective and sustainable lignocellulosic bio-hydrogen production in the future.

Antifungal activity of water-soluble products obtained following the liquefaction of cornstalk with sub-critical water

Cornstalks are the leftover leaves and stems in a field after corn harvest. They are a potential biomass resource but are underutilized in agricultural production systems. To examine the chemical components in cornstalks and their corresponding functions, blocky cornstalks were treated in water at temperatures of 190, 210, 230, 250, and 270 °C in a high-pressure reactor. Water-soluble products (WSPs) were extracted from these treatments, and their chemical compositions were analyzed using gas chromatography-mass spectrometry (GC-MS), and their antifungal activities were determined using a bioassay. It was found that WSPs contained 28.7-40.1% phenols, 27.9-36.6% ketones, 0-2.6% alcohols, 4.9-10.1% esters, 5.4-7.8% organic acids, 1.3-12% aldehydes, and 5.5-18.4% of other organic compounds such as nitrogen- and sulfur-containing compounds, furan compounds, and benzene compounds. The inhibition the growth of the plant pathogen Fusarium oxysporum by WSPs was affected by temperature. WSP-270 (obtained at 270 °C) exhibited the best growth-inhibition efficacy. Under a biomicroscope, WSP-270-treated F. oxysporum showed a deformed and swollen hypha, and an increased number of bifurcations, as well as an expansion of growing apexes of new bifurcations. Therefore, the antifungal activity of WSPs could be used to manage soilborne plant pathogens.

Honeycomb-like magnetic cornstalk for Cr(VI) removal and ammonium release

In this work, cornstalk (CS) was irradiated by high energy electron beam to obtain honeycomb-like porous CS (PCS). The PCS was loaded with ammonium sulfite (AS) and then coated by polyvinyl alcohol (PVA)-Fe₃O₄ to obtain PCS-AS@PVA-Fe₃O₄. The PCS-AS@PVA-Fe₃O₄ could reduce hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) by SO₃^2-, then the Cr(III) combined with PCS-AS@PVA-Fe₃O₄ through hydrogen bonds. The resulting PCS-AS@PVA-Fe₃O₄/Cr with a high magnetism could be conveniently separated from water via a magnet. PCS-AS@PVA-Fe₃O₄/Cr showed a high performance on controlling Cr(VI) migration in soil and uptake by plant. Meanwhile, ammonium could be released from PCS-AS@PVA-Fe₃O₄, favoring plant growth. Therefore, this work not only provides a promising and low-cost approach to remove Cr(VI) and promote plant growth simultaneously, but also provides a new route for CS recycling, which might have a potential application value.

Co-biodrying of sewage sludge and organic fraction of municipal solid waste: A thermogravimetric assessment of the blends

This study investigated the thermogravimetric properties of sewage sludge and organic fraction of municipal solid waste (OFMSW) during their co-biodrying at different fractions. Sewage sludge and OFMSW were co-biodried at the mass proportion of 0%, 42.5% and 85% (of the total wet weight), respectively, with 15% cornstalk as the bulking agent. Results show that of these three raw materials, OFMSW exhibited the lowest ignition temperature and the highest burnout temperature. Moreover, OFMSW had a better comprehensive combustion performance (S) than sewage sludge. Blending OFMSW, sewage sludge and cornstalk showed the highest S value (4.0 × 10^-7%² min^-2 °C^-3). In addition, there existed certain interactions between the co-combustion process, especially at high temperature stage. The burning characteristics, including ignition performance, burnout efficiency, DTG_max and S increased with fluctuations in the first 6-9 days of co-biodrying process, and then declined in all treatments. Hence, 15-day of biodrying made the product with poor burning behavior (S value of 1.0 × 10^-7-1.4 × 10^-7%² min^-2 °C^-3). More importantly, the optimal combustion performance was observed when co-biodrying the same amount (42.5%) of sewage sludge and OFMSW with the peak of 8.3 × 10^-7%² min^-2 °C^-3 achieved on day 9. In addition, the blends were easier to burn after the biodrying process.

Reduce recalcitrance of cornstalk using post-hydrothermal liquefaction wastewater pretreatment

Hydrothermal pretreatment (HTP) using an acidic catalyst is known to be effective for reducing lignocellulosic biomass recalcitrance. Post-hydrothermal liquefaction wastewater (PHW) from hydrothermal liquefaction of swine manure contains a large fraction of organic acids and thus was introduced to improve the HTP of cornstalk in this study. The response surface methodology was performed to optimize operating parameters of HTP for preserving structural polysaccharides while removing the barrier substances. A remarkable co-extraction of cell wall polymers was observed during PHW-catalyzed HTP at 172 °C for 88 min. The analysis of particle size, crystalline cellulose, the degree of polymerization (DP), mole number (MN) and SEM suggested that the co-extraction effect could distinctively alter lignocellulosic structures associated with recalcitrance and thus accelerate biomass saccharification. Additionally, the biodegradability of PHW was improved after HTP as a result of balanced nutrients and increased acids and sugars suitable for biogas production via anaerobic fermentation.

New production process of the antifungal chaetoglobosin A using cornstalks

Chaetoglobosin A is an antibacterial compound produced by Chaetomium globosum, with potential application as a biopesticide and cancer treatment drug. The aim of this study was to evaluate the feasibility of utilizing cornstalks to produce chaetoglobosin A by C. globosum W7 in solid-batch fermentation and to determine an optimal method for purification of the products. The output of chaetoglobosin A from the cornstalks was 0.34 mg/g, and its content in the crude extract was 4.80%. Purification conditions were optimized to increase the content of chaetoglobosin A in the crude extract, including the extract solvent, temperature, and pH value. The optimum process conditions were found to be acetone as the extractant, under room temperature, and at a pH value of 13. Under these conditions, a production process of the antifungal chaetoglobosin A was established, and the content reached 19.17%. Through further verification, cornstalks could replace crops for the production of chaetoglobosin A using this new production process. Moreover, the purified products showed great inhibition against Rhizoctonia solani, with chaetoglobosin A confirmed as the main effective constituent (IC₅₀ = 3.88 μg/mL). Collectively, these results demonstrate the feasibility of using cornstalks to synthesize chaetoglobosin A and that the production process established in this study was effective.

Highly efficient organosolv fractionation of cornstalk into cellulose and lignin in organic acids

In this study, effects of fractionation solvents, catalysts, temperatures and residence time on yields, purity and chemical composition of the products were investigated at the solid/solvent ratio of 1:5 (g/g). It was revealed that mixture of acetic acid/formic acid/water at the ratio of 3:6:1 (v/v/v) resulted in crude cellulose and lignin products of relatively high purity. The use of HCl catalyst contributed to a high crude cellulose yield, while H2SO4 showed an adverse effect on cellulose yield. However, both of these acidic catalysts contributed to much lower hemicellulose contents in the resulted crude cellulose products compared with those obtained without a catalyst. Fractionation at 90°C for 180min in mixed solvents of acetic acid/formic acid/water (3:6:1, v/v/v) with or without catalyst produced crude cellulose with very low residual lignin contents (<4%).

Recovery of reducing sugars and volatile fatty acids from cornstalk at different hydrothermal treatment severity

This study focused on the degradation of cornstalk and recovery of reducing sugars and volatile fatty acids (VFAs) at different hydrothermal treatment severity (HTS) (4.17-8.28, 190-320°C). The highest recovery of reducing sugars and VFAs reached 92.39% of aqueous products, equal to 34.79% based on dry biomass (HTS, 6.31). GC-MS and HPLC identified that the aqueous contained furfural (0.35-2.88 g/L) and 5-hydroxymethyl furfural (0-0.85 g/L) besides reducing sugars and VFAs. Hemicellulose and cellulose were completely degraded at a HTS of 5.70 and 7.60, respectively. SEM analysis showed that cornstalk was gradually changed from rigid and highly ordered fibrils to molten and grainy structure as HTS increased. FT-IR and TGA revealed the significant changes of organic groups for cornstalk before and after hydrothermal treatment at different HTS. Hydrothermal treatment might be promising for providing feedstocks suitable for biohythane production.

Performance and microbial community of carbon nanotube fixed-bed microbial fuel cell continuously fed with hydrothermal liquefied cornstalk biomass

Hydrothermal liquefaction (HTL) is a green technology for biomass pretreatment with the omission of hazardous chemicals. This study reports a novel integration of HTL and carbon nanotubes (CNTs) fixed-bed microbial fuel cell (FBMFC) for continuous electricity generation from cornstalk biomass. Two FBMFCs in parallel achieved similar performance fed with cornstalk hydrolysate at different organic loading rates (OLRs) (0.82-8.16g/L/d). About 80% of Chemical oxygen demand (COD) and Total organic carbon (TOC) was removed from low-Biochemical oxygen demand (BOD)/COD (0.16) cornstalk hydrolysate at 8.16g/L/d, whereas a maximum power density (680mW/m(3)) was obtained at 2.41g/L/d, and a smallest internal resistance (Rin) (28Ω) at 3.01g/L/d. Illumina MiSeq sequencing reveals the diverse microbial structure induced by the complex composition of cornstalk hydrolysate. Distinguished from Proteobacteria, which a number of exoelectrogens belong to, the identified dominant genus Rhizobium in FBMFC was closely related to degradation of cellulosic biomass.

Consolidated bioprocessing performance of Thermoanaerobacterium thermosaccharolyticum M18 on fungal pretreated cornstalk for enhanced hydrogen production

BACKGROUND

Biological hydrogen production from lignocellulosic biomass shows great potential as a promising alternative to conventional hydrogen production methods, such as electrolysis of water and coal gasification. Currently, most researches on biohydrogen production from lignocellulose concentrate on consolidated bioprocessing, which has the advantages of simpler operation and lower cost over processes featuring dedicated cellulase production. However, the recalcitrance of the lignin structure induces a low cellulase activity, making the carbohydrates in the hetero-matrix more unapproachable. Pretreatment of lignocellulosic biomass is consequently an extremely important step in the commercialization of biohydrogen, and for massive realization of lignocellulosic biomass as alternative fuel feedstock. Thus, development of a pretreatment method which is cost efficient, environmentally benign, and highly efficient for enhanced consolidated bioprocessing of lignocellulosic biomass to hydrogen is essential.

RESULTS

In this research, fungal pretreatment was adopted for enhanced hydrogen production by consolidated bioprocessing performance. To confirm the fungal pretreatment efficiency, two typical thermochemical pretreatments were also compared side by side. Results showed that the fungal pretreatment was superior to the other pretreatments in terms of high lignin reduction of up to 35.3% with least holocellulose loss (the value was only 9.5%). Microscopic structure observation combined with Fourier transform infrared spectroscopy (FTIR) analysis further demonstrated that the lignin and crystallinity of lignocellulose were decreased with better holocellulose reservation. Upon fungal pretreatment, the hydrogen yield and hydrogen production rate were 6.8 mmol H2 g(-1) pretreated substrate and 0.89 mmol L(-1) h(-1), respectively, which were 2.9 and 4 times higher than the values obtained for the untreated sample.

CONCLUSIONS

Results revealed that although all pretreatments could contribute to the enhancement of hydrogen production from cornstalk, fungal pretreatment proved to be the optimal method. It is apparent that besides high hydrogen production efficiency, fungal pretreatment also offered several advantages over other pretreatments such as being environmentally benign and energy efficient. This pretreatment method thus has great potential for application in consolidated bioprocessing performance of hydrogen production.