Fe-MOF/AuNP-based ratiometric electrochemical immunosensor for the detection of deoxynivalenol in grain products.

A ratiometric assay was designed to improve the sensitivity and reliability of electrochemical immunosensors for deoxynivalenol (DON) detection. The indicator signal caused by the Fe-based metal-organic framework nanocomposites loaded with gold nanoparticles and the internal reference signal from the [Fe(CN)6]3-/4- in the electrolyte came together at the immunosensor. When immunoreactivity occurred, the indicator signals decreased as the concentration of DON increased, while the internal reference signals increased slightly. The ratio of the indicator signal to the internal reference signal was available for reproducible and sensitive monitoring of DON. The prepared immunosensor showed excellent performance in the range from 0.5 to 5000 pg mL-1, and the detection limit was 0.0166 pg mL-1. The immunosensor achieved satisfactory detection toward DON in spiked and actual samples and has a promising application in the control of DON in grain products.

[Bioconversion of C1 gases and genetic engineering modification of gas-utilizing microorganisms].

C1 gases including CO, CO2 and CH4, are mainly derived from terrestrial biological activities, industrial waste gas and gasification syngas. Particularly, CO2 and CH4 are two of the most important greenhouse gases contributing to climate change. Bioconversion of C1 gases is not only a promising solution to addressing the problem of waste gases emission, but also a novel route to produce fuels or chemicals. In the past few years, C1-gas-utilizing microorganisms have drawn much attention and a variety of gene-editing technologies have been applied to improve their product yields or to expand product portfolios. This article reviewed the biological characteristics, aerobic or anaerobic metabolic pathways as well as the metabolic products of methanotrophs, autotrophic acetogens, and carboxydotrophic bacteria. In addition, gene-editing technologies (e.g. gene interruption technology using homologous recombination, group Ⅱ intron ClosTron technology, CRISPR/Cas gene editing and phage recombinase-mediated efficient integration of large DNA fragments) and their application in these C1-gas-utilizing microorganisms were also summarized.

An electrochemical immunosensor based on prussian blue@zeolitic imidazolate framework-8 nanocomposites probe for the detection of deoxynivalenol in grain products.

The presence of deoxynivalenol (DON) in grains poses a threat to human health, which is critical for sensitive detection of DON. In this electrochemical immunosensor, zeolitic imidazolate framework-8 (ZIF-8) loaded with Prussian blue (PB) nanoparticles was coated by polydopamine (PDA) as a redox probe. The high porosity of ZIF-8, the unique electrochemical activity of PB and the outstanding electrical conductivity of PDA improved the sensitivity of the immunosensor. Under the optimized conditions, the peak current in differential pulse voltammetry displayed a good linear relationship over DON concentrations in a range of 0.1-5000 pg mL-1 with a detection limit of 0.0186 pg mL-1. In addition, the immunosensor also had good selectivity and stability. Good recoveries of 85.67 to 118.00 % have been achieved for the detection of DON in spiked grain products. This new strategy exhibits great potential for simple and rapid detection of DON in grain and feed products.

A one-step deconstruction-separation organosolv fractionation of lignocellulosic biomass using acetone/phenoxyethanol/water ternary solvent system.

A novel ternary solvent system for organosolv fractionation of lignocellulosic biomass, named APW process, which is composed of acetone, phenoxyethanol and water with the advantages of monophasic deconstruction and biphasic separation of components was developed. Through fractionation of amorpha as a case study, a monophasic APW solution (acetone/phenoxyethanol/water = 5:11:4, volume ratio) with the best lignin affinity was constructed based on Hansen solubility parameters. According to Taguchi experimental design, the optimal conditions were 130 °C, 70 min, 0.15 M sulfuric acid and 20 LSR. Under optimal conditions, removal of lignin and hemicellulose reached 95.60% and 98.39%, respectively. While 80.48% of cellulose was retained in residue and its digestibility was 80.36%. Then, 83.74% of hemicellulose was recovered from aqueous as sugars, and 35.64% of lignin was recovered by precipitation. Moreover, APW process also have effective fractionation of sugarcane bagasse, corn cob and pine, cellulose and hemicellulose recovery were both over 80%.

Facile synthesis of lignin-based epoxy resins with excellent thermal-mechanical performance.

Up to now, various approaches have been used to fabricate lignin-based epoxy thermosets by utilizing lignin or lignin-derivatives, but there is still lack of a simple, effective and environmental-friendly pathway for producing lignin-based epoxy resins from industrial lignin. In this work, a novel strategy - one-pot to synthesize phenolated lignin incorporated novolac epoxy networks (PLIENs) was proposed. As expected, PLIENs obtained from the novel route exhibited preferable mechanical and thermal properties compared with the epoxy resins which obtained from common route. Moreover, increasing the loading of lignin did not significantly deteriorate the thermal-mechanical performance of cured epoxy resins. However, the Tg of PLIENs was slightly lowered compared with conventional petroleum-based epoxy resins (DGEBA). Nonetheless, the flexural strength and storage modulus of PLIENs were higher than that of DGEBA. Especially, the char yield of PLIENs at 800 °C was up to 28.9%, much higher than that of DGEBA (only 6.9%), which indicated that lignin has a certain promoting effect on the flame retardancy of epoxy resins. This research provides a new insight for producing commercially viable lignin-based epoxy thermosets.

Impact of Alkaline Pretreatment Condition on Enzymatic Hydrolysis of Sugarcane Bagasse and Pretreatment Cost.

A combined severity factor (RCSF) which is usually used to evaluate the effectiveness of hydrothermal pretreatment at above 100 °C had been developed to assess the influence of temperature, time, and alkali loading on pretreatment and enzymatic hydrolysis of lignocellulose. It is not suitable for evaluating alkaline pretreatment effectiveness at lower than 100 °C. According to the reported deducing process, this study modified the expression of [Formula: see text] as [Formula: see text] which is easier and more reasonable to assess the effectiveness of alkaline pretreatment. It showed that RCSF exhibited linear trend with lignin removal, and quadratic curve relation with enzymatic hydrolysis efficiency (EHE) at the same temperature. The EHE of alkali-treated SCB could attain the maximum value at lower RCSF, which indicated that it was not necessary to continuously enhance strength of alkaline pretreatment for improving EHE. Within a certain temperature range, the alkali loading was more important than temperature and time to influence pretreatment effectiveness and EHE. Furthermore, the contribution of temperature, time, and alkali loading to pretreatment cost which was seldom concerned was investigated in this work. The alkali loading contributed more than 70% to the pretreatment cost. This study laid the foundation of further optimizing alkaline pretreatment to reduce cost for its practical application.

The effect of enzyme loading, alcohol/acid ratio and temperature on the enzymatic esterification of levulinic acid with methanol for methyl levulinate production: a kinetic study.

As an important bio-based chemical, methyl levulinate (ML) can be produced via enzymatic esterification of levulinic acid with methanol. A kinetic model is developed in this work based on the law of mass action and reaction reversibility, to investigate the effect of enzyme loading, alcohol/acid ratio and temperature on ML yield. Data analysis shows that newly developed binary regression is apparently more persuasive than the commonly used unitary regression. Kinetic study reveals: (1) rate constants of esterification/hydrolysis increase with increasing enzyme loading, while their ratio (equilibrium constant) remains invariant. (2) Methanol has no toxicity towards lipase, and hence, neither the rate constants of esterification/hydrolysis nor the equilibrium constant are affected by alcohol/acid ratio. (3) Both rate constants of esterification/hydrolysis and the equilibrium constant increase with temperature elevation, and their relationships agree with Arrhenius equation and Van't Hoff equation, respectively. (4) The esterification is endothermic and spontaneous. In total, the application of binary regression analysis for the developed model to study the enzymatic esterification kinetics is quite successful.

Synthesis of a Stable Solid Acid Catalyst from Chloromethyl Polystyrene through a Simple Sulfonation for Pretreatment of Lignocellulose in Aqueous Solution.

A stable solid acid catalyst, SCPR140-1, was synthesized from chloromethyl polystyrene resin (CPR) and used for catalytic pretreatment of corncob in aqueous solution. Under the optimized pretreatment condition, 73.07 % of xylose was directly obtained, and the enzymatic digestibility of treated residue reached up to 94.65 %, indicating that the SCPR140-1 had high selectivity for xylose production and effectively deconstructed the structure of corncob. The -CH2 Cl group of CPR was substituted by -SO3 H through the sulfonation, and the -SO3 H was stably bound on the catalyst during the pretreatment process. Compared with other similar reports, the SCPR140-1 was not only synthesized through a simpler process but also had a more stable catalytic activity during multiple recycling runs.

Depolymerization of holocellulose from Chinese herb residues by the mixture of lignin-derived deep eutectic solvent with water.

The depolymerization of biomass carbohydrate polymers usually happened in homogeneous medium, just a few in heterogeneous solution. Herein, holocellulose from two Chinese herb residues Cortex albiziae (HRCA) and Heteropogon contortus (HRHC) was prepared and characterized. Deep eutectic solvent (DES) of choline chloride/p-coumaric acid collaborating with water was employed for the dissociation of those two holocelluloses and selectively dissolved hemicellulose into xylose with maximal yields of 81.50 % and 72.47 %, respectively. Most cellulose remained as the polymer state with a maximum solubility of 9.38 %. The synergistic action of DES and water was investigated to unveil the depolymerization mechanism and the roles of each component in depolymerizing procedure. It was water that released hemicellulose polymers and dissolved polymers to soluble short oligosaccharides, and DES rapidly cleaved the latter to xylose. Contrarily, DES broke cellulose to only soluble cello-oligosaccharides, but water exhibited the ability to hydrolyze cellulose to glucose.

Effect of a Nonionic Surfactant on Enzymatic Hydrolysis of Lignocellulose Based on Lignocellulosic Features and Enzyme Adsorption.

Reduction in the adsorption of cellulase onto lignin has been thought to be the common reason for the improvement of enzymatic hydrolysis of lignocellulose (EHLC) by a nonionic surfactant (NIS). Few research studies have focused on the relationship between lignocellulosic features and NIS for improving EHLC. This study investigated the impact of Tween20 on the enzymatic hydrolysis and enzyme adsorption of acid-treated and alkali-treated sugarcane bagasse (SCB), cypress, and Pterocarpus soyauxii (PS) with and without being ground. After addition of Tween20, the adsorption of cellulase onto unground and ground alkali-treated SCB increased, and the unground acid-treated SCB exhibited little change in adsorption cellulase, while other unground and ground, treated samples showed decreased cellulase adsorption. Tween20 could improve the enzymatic hydrolysis of acid-treated SCB, while it had little influence on the enzymatic hydrolysis of other treated materials. After being ground, both cellulase adsorption and enzymatic hydrolysis of treated lignocelluloses increased, and Tween20 could enhance the enzymatic hydrolysis of acid-treated materials while hardly affected the enzymatic hydrolysis of alkali-treated materials. This indicated that the promotion effect of Tween20 on enzymatic hydrolysis of treated lignocellulose could not be mainly ascribed to the hindrance of Tween20 to cellulase adsorption on lignin but was related to the lignocellulosic features such as hemicellulose removal and surface morphology changes.

Performance of a microalgal-bacterial consortium system for the treatment of dairy-derived liquid digestate and biomass production.

To enhance the treatment performance of dairy-derived liquid digestate (DLD) using microalgal-bacterial consortium system composed of Chlorella vulgaris and indigenous bacteria (CV), activated sludge was introduced to form a new microalgal-bacterial consortium system (Co-culture). The activated sludge shortened the lag phase and increased the specific growth rate of C. vulgaris (0.56 d-1). The biomass yield in the Co-culture was 2.72 g L-1, which was lower than that in the CV (3.24 g L-1), but the Co-culture had an improved COD (chemical oxygen demand) removal (25.26%) compared to the CV (13.59%). Quantitative PCR and metagenomic analyses demonstrated that microalgae also promoted bacterial growth, but influenced differently on the bacterial communities of indigenous bacteria and activated sludge. Compared with indigenous bacteria, activated sludge was more prone to forming a favorable symbiosis with C. vulgaris. These findings contribute to the construction of efficient microalgal-bacterial consortium system in wastewater treatment.

Structural insights reveal the effective Spirulina platensis cell wall dissociation methods for multi-output recovery.

In this work, Spirulina platensis cells harvested in the exponential and equilibrium phases with intact and broken cell walls were treated through a set of alkaline or acidic conditions including alkalis and acids, with solutions of pH 0.0-14.0. The effective Spirulina platensis cell wall dissociation methods for multi-output recovery were obtained. SEM and FTIR were applied to characterize the alkaline and acid treatment details, and Spirulina platensis cell wall dissociation mechanisms, via attacks by OH- or H+, were then proposed. Overall, this study highlights the synthesized multi-output algal product in an integrated strategy with ultracellular structural insight and is valuable for understanding the specific roles of attack ions.

Effects of fermentative and non-fermentative additives on silage quality and anaerobic digestion performance of Pennisetum purpureum.

The effect of additives on the silage quality, microbial community, and anaerobic digestion performance of Pennisetum purpureum with high moisture content was studied. The sample treated with a mixed additive had best silage quality with the lowest pH and highest lactic acid/acetic acid ratio. Different additives influenced the dominant desirable bacteria. Correspondingly, Enterobacter was the dominant bacterial genus for sample with non-fermentative additives, whereas for the samples with fermentative or mixed additives, both Enterobacter and Lactobacillus had high relative abundance. The parameters of NH3-N, hemicellulose and lactic acid were positively correlated with the specific methane yield, while the lignin content was inversely correlated with the specific methane yield. The higher specific methane yield of 293.81 ± 0.15-334.69 ± 22.75 mL/g VS was obtained for samples treated with fermentative additive. Therefore, the mixed additive and fermentative additive are recommended for the silage of material with high-moisture content to improve the silage quality and methane yield.

Enhanced methane production from anaerobic digestion of hybrid Pennisetum by selectively removing lignin with sodium chlorite.

To enhance the biodegradability and methane production of hybrid Pennisetum, a pretreatment method with high selectivity for lignin removal, namely sodium chlorite/acetic acid (SCA) pretreatment, was examined in this work. Results showed that SCA pretreatment can selectively remove lignin with minimal impact on cellulose and hemicellulose. After up to 200 min of SCA treatment, 79.4% of lignin was removed and over 90% of the holocellulose was retained. The physicochemical changes after pretreatment were analyzed by confocal laser scanning microscopy, X-ray diffractometer and Fourier transform infrared spectroscopy, showing that the majority of lignin was removed from secondary cell walls and cell middle lamella while the chlorite-resistant lignin remained in the cell corner. Lignin removal significantly enhanced the biodegradability from 59.6% to 86.4% and increased methane production by 38.3%. Energy balance showed that SCA pretreatment was efficient to increase the energy output of hybrid Pennisetum.

Low-temperature sodium hydroxide pretreatment for ethanol production from sugarcane bagasse without washing process.

A low-temperature sodium hydroxide (NaOH) pretreatment for sugarcane bagasse (SCB) was obtained via the surface response design in this study. However, a large quantity of water consumption and wastewater generation which have been the common problems for alkaline pretreatment of lignocellulose still exists in this pretreatment. In order to reduce water consumption and wastewater generation, this study attempted to perform enzymatic hydrolysis and fermentation of NaOH-treated SCB without washing process. It showed that after pretreatment and solid-liquid separation, NaOH-treated SCB could be directly hydrolysed by cellulase via pH and solid-liquid adjustment without washing steps, and the maximum enzymatic hydrolysis efficiency could reach to 70.2%. A domesticated Saccharomyces cerevisiae Y2034 which can endure 6-times diluted BL was obtained, and realized 67.5% ethanol yield from the enzymatic hydrolysate of unwashed NaOH-treated SCB. It provided a clue for converting NaOH-treated lignocellulose to ethanol at low water consumption and wastewater generation.

Cultivation of Chlorella vulgaris on unsterilized dairy-derived liquid digestate for simultaneous biofuels feedstock production and pollutant removal.

In order to assess viability of microalgae cultivation using unsterilized dairy-derived liquid digestate (DLD) for simultaneous biofuels feedstock production and contaminant removal, four DLD concentrations (25%, 50%, 75% and 100%) were used to grow Chlorella vulgaris in batch photobioreactors (PBRs). The 25% DLD was an ideal alternative medium in that high growth rate (0.69 d-1), high lipid productivity (112.9 mg L-1 d-1) as well as high nutrient removal were attained. The high DLD concentration caused inhibition of microalgal growth, where COD was more inhibitive than ammonium. The presence of bacteria did not influence microalgae production because of limited growth. Microalgal growth reduced the richness and diversity of bacterial community. Furthermore, the species of Bacteroidetes, Candidatus Saccharibacteria, and Chlamydiae rather than Proteobacteria benefited microalgal-bacterial symbiosis. These findings contribute to better application of microalgal-bacterial system for large-scale microalgae cultivation as well as environmental sustainability.

Engineering Corynebacterium glutamicum Mutants for 3-Methyl-1-butanol Production.

3-Methyl-1-butanol (3MB) is a promising biofuel that can be produced from 2-ketoisocaproate via the common L-leucine biosynthesis pathway. Corynebacterium glutamicum was chosen as a host bacterium because of its strong resistance to isobutanol. In the current study, several strategies were designed to overproduce 3MB in C. glutamicum through a non-fermentation pathway. The engineered C. glutamicum mutant was obtained by silencing the pyruvate dehydrogenase gene complex (aceE) and deleting the lactic dehydrogenase gene (ldh), followed by mutagenesis with diethyl sulfate (DES) and selection with Fmoc-3-4-thiazolyl-L-alanine (FTA). The mutant could produce 659 mg/L of 3MB after 12 h of incubation. To facilitate carbon flux to 3MB biosynthesis, the engineered recombinant was also constructed without branched-chain acid aminotransferase (ilvE) activity by deleting the ilvE gene. This recombinant could produce 697 mg/L of 3MB after 12 h of incubation.

Treatment of low C/N ratio wastewater and biomass production using co-culture of Chlorella vulgaris and activated sludge in a batch photobioreactor.

The aim of this work was to study the performance of pollutants removal and biomass production by co-culture of Chlorella vulgaris and activated sludge in a batch photobioreactor (PBR), compared with their single system to treat a low C/N ratio (COD/N = 4.3) wastewater. The co-culture system surpassed activated sludge system in terms of nutrients removal and outperformed microalgae alone system in regard to COD removal. Biomass productivity of the co-culture system was 343.3 mg L-1 d-1, and the harvested biomass could be developed as biofuels, animal feeds or soil conditioners due to the improved calorific value and cellular composition compared with activated sludge. The low C/N ratio wastewater enabled bacteria to maintain a relatively low level, hence in favor of microalgae enrichment and nutrient recovery.

In situ deep eutectic solvent pretreatment to improve lignin removal from garden wastes and enhance production of bio-methane and microbial lipids.

Biomass pretreatment can improve the conversion efficiency of bioenergy production. Liquid hot water (LHW) pretreatment is a truly green pretreatment due to its zero chemical use, but has the disadvantages of low lignin removal and pseudo-lignin formation. A modified liquid hot water (MLHW) process based on in situ synthesis of deep eutectic solvent (DES) could efficiently improve delignification of Roystonea regia leaves (LR) and leaf sheaths (LSR). LSR was less recalcitrant than LR, and its characteristics of higher porosity (34.8%) and thinner cell walls (5.2 µm) for LSR contributed it higher lignin removal (53.6%) and lower choline chloride (ChCl) consumption (H2O-ChCl mass ratio of 2:1) than those (44.6% and 1:2) from LR. Moreover, a great improvement of 309.0% in bio-methane yield was achieved for the MLHW-treated LSR. In addition, in situ DES in MLHW had good biocompatibility with cellulase, microalgae, and yeast.

Synthesis of a novel nano-rod-shaped hierarchical silicoaluminophosphate SAPO-11 molecular sieve with enhanced hydroisomerization of oleic acid to iso-alkanes.

In this article, a novel nano-rod-shaped SAPO-11 molecular sieve (SAPO-11-A-F) with a thickness of ca. 100 nm was successfully fabricated by the in situ seed-induced steam-assisted method using the cationic surfactant cetyltrimethylammonium bromide (CTAB) as a mesoporous template and a nonionic copolymer poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide), F127, as the crystal growth inhibitor. The fabricated nano-rod-shaped SAPO-11-A-F possessed nanocrystalline size, a hierarchical porous structure, and enhanced acidic sites. The added CTAB was mainly used to enhance the mesoporous structure and acid, and F127 acted as a grain growth inhibitor. According to the orientation growth mechanism of the molecular sieves, the crystallization mechanism of the nano-rod-shaped hierarchical porous molecular sieves with different crystallization times was investigated. It was found that the nano-rod-shaped molecular sieves were formed by the accumulation of nano-sheets. Compared to three nickel catalysts with different silicoaluminophosphate SAPO-11 molecular sieves in the hydroisomerization of oleic acid to iso-alkanes, the bifunctional catalyst of 7% Ni/SAPO-11-A-F had higher isomeric selectivity (79.8%); in particular, the isomeric octadecane showed stronger selectivity, indicating that the nano-rod-shaped SAPO-11 molecular sieve is more beneficial for the hydrodehydration reaction.