Search

With the purpose of developing a novel approach of agricultural waste treatment and overcoming bottlenecks for upscaling solid-state fermentation processes, the type of aerated, continuously stirred solid-state bioreactors were used for the production of γ-PGA by Bacillus amyloliquefaciens JX-6. Using corn stalk and soybean meal, the most common agricultural waste in China, as solid substrates, the maximum production of γ-PGA was 116.88 ± 5.05 g/kg and 102.48 ± 3.30 g/kg in 50 L and 150 L bioreactors, respectively. Production of γ-PGA in 50 L bioreactor was higher than in 150 L bioreactor, demonstrating that a reduction in γ-PGA production occurred as the fermentation system enlarged. An analysis of the interactions among fermentation parameters (temperature, moisture, and pH), γ-PGA production, solid substrates and bacterial communities indicated that different bioreactor capacities caused changes in fermentation parameters and bacterial communities, which in turn affected substrate utilization and γ-PGA production. Overall, obtaining considerable amounts of γ-PGA under non-sterilized fermentation expressed that JX-6 has excellent abilities to adapt to these substrates and conditions. Bioconversion of agricultural waste into γ-PGA in scale-up fermentation was successfully conducted by creating a more stable and suitable fermentation environment in bioreactors.

Phenolic compounds are problematic byproducts generated from lignocellulose pretreatment. In this study, the feasibility degradation of syringic acid (SA), vanillic acid (VA), and 4-hydroxybenzoic acid (HBA) by Bio-Electro-Fenton (BEF) system with a novel Fe–Mn/graphite felt (Fe–Mn/GF) composite cathode were investigated. The nano-scale Fe–Mn multivalent composite catalyst with core shell structure distributed more evenly on GF surface to form a catalyst layer with higher oxygen reduction reaction performance. Accordingly, the maximum power density generated with Fe–Mn/GF cathode was 48.1% and 238.9% higher than Fe/GF and GF respectively, which further enhanced the in situ generation of H2O2 due to the superiority of nano-scale core shell structure and synergistic effect of Fe and Mn species. The degradation efficiency of the three phenolic compounds in the BEF system could reached 100% after optimization of influencing parameters. Furthermore, a possible SA degradation pathway by BEF process in the present system was proposed based on the detected intermediates. These results demonstrated an efficient approach for the degradation of phenolic compounds derived from lignocellulose hydrolysates.

Background: Gemcitabine is considered a classical agent for the treatment of patients with pancreatic cancer. However, gemcitabine resistance is a common cause of treatment failure, leading to poor survival. Therapy to overcome gemcitabine resistance would benefit patients with pancreatic cancer. This study investigated the impact of aspirin (ASA) to gemcitabine resistance in the biological function of pancreatic cancer cells and the potential mechanism. Methods: The MTT assay, wound healing assay and annexin V-FITC/PI test was used to determine whether ASA could inhibit gemcitabine resistance in pancreatic cancer cells. Besides, the expression of Bcl-2, Bax, E-cadherin, Vimentin, p-PI3K, p-AKT and p-mTOR was detected by the Western blot. Statistically significant differences between groups were determined with the Student’s t-test. Results: The proliferation and migration of SW1990 and BxPC3 cells were significantly decreased while the apoptosis rate was increased in the combination of ASA and gemcitabine group (pppConclusion: Our research provided evidence ASA could help to inhibit gemcitabine resistance of pancreatic cancer cells, probably via inhibiting the PI3K/AKT/mTOR pathway and reversing EMT. Thus, combined use of ASA and gemcitabine is expected to be a potential therapeutic strategy for pancreatic cancer patients.

Adenosine, which is produced mainly by microbial fermentation, plays an important role in the therapy of cardiovascular disease and has been widely used as an antiarrhythmic agent. In this study, guanosine 5′-monophosphate (GMP) synthetase gene (guaA) was inactivated by gene-target manipulation to increase the metabolic flux from inosine 5′-monophosphate (IMP) to adenosine in B. subtilis A509. The resulted mutant M3-3 showed an increased adenosine production from 7.40 to 10.45 g/L, which was further enhanced to a maximum of 14.39 g/L by central composite design. As the synthesis of succinyladenosine monophosphate (sAMP) from IMP catalysed by adenylosuccinate synthetase (encoded by purA gene) is the rate-limiting step in adenosine synthesis, the up-regulated transcription level of purA was the potential underlying mechanism for the increased adenosine production. This work demonstrated a practical strategy for breeding B. subtilis strains for industrial nucleoside production.

Due to the promising applications, the demand to enhance poly-γ-glutamic acid (γ-PGA) production while decreasing the cost has increased in the past decade. Here, xylose/glucose mixture and corncob hydrolysate (CCH) was evaluated as alternatives for γ-PGA production by Bacillus amyloliquefaciens C1. Although both have been validated to support cell growth, glucose and xylose were not simutaneously consumed and exhibited a diauxic growth pattern due to carbon catabolite repression (CCR) in B. amyloliquefaciens C1, while the enhanced transcription of araE alleviated the xylose transport bottleneck across a cellular membrane. Additionally, the xyl operon (xylA and xylB), which was responsible for xylose metabolism, was strongly induced by xylose at the transcriptional level. When cultured in a mixed medium, xylR was sharply induced to 3.39-folds during the first 8-h while reduced to the base level similar to that in xylose medium. Finally, pre-treated CCH mainly contained a mixture of glucose and xylose was employed for γ-PGA fermentation, which obtained a final concentration of 6.56 ± 0.27 g/L. Although the glucose utilization rate (84.91 ± 1.81%) was lower than that with chemical substrates, the xylose utilization rate (43.41 ± 2.14%) and the sodium glutamate conversion rate (77.22%) of CCH were acceptable. Our study provided a promising approach for the green production of γ-PGA from lignocellulosic biomass and circumvent excessive non-food usage of glucose.

In this study, a double E strategy (enzymes and enhancer) characterized by high efficiency for enhancing sewage sludge anaerobic digestion (AD) is proposed. This strategy combines addition of trace elements (TEs) enhancer and enzyme pretreatment, inducing a synergistic effect on AD, and it is more effective and economical compared with TEs addition or enzyme pretreatment in isolation. When adding 400 U/g cocktail enzymes and 1.24% trance elements enhancers, the cumulative methane production and the maximum daily methane increased yield by 45.29% and 84.7%, respectively. According to microbial community analysis, the double E strategy significantly motivate the growth of acetogens and protein fermenting bacterium. The relative abundance of Fermentimonas and Lutispora increased by 6.15% and 5.4%, respectively. Archaeal community analysis and changes in the mcrA gene abundance demonstrate enrichment of hydrogenotrophic methanogens, with the methanogens exhibiting high vitalities and stress resistance. The double E strategy could be a promising way to improve industrial sewage sludge AD efficiency.

The impacts of different S/N molar ratios and fillers (polyurethane foam, multi-surface hollow spheres, and pall rings) on the process of simultaneous desulfurization and denitrification (SDD) were studied by using anaerobic biotrickling filer (BTF). Furthermore, the SDD mechanism was described by dividing the SDD process into three stages based on pH changes: (I) increase (II) decrease and (III) stable state. The maximum desulfurization and denitrification efficiency (13.5 g-S m−3 h−1 and 3.7 g-N m−3 h−1, respectively) was achieved by applying polyurethane foam as filler. When S2− and S0 coexist as electron donors in the SDD system, the functional microbes degrade S2− preferentially. The S/N molar ratios of the influent were higher, and the relative content of sulfate in the products was less. Considering the efficiency and economic benefits, polyurethane foam is suggested as fillers for practical implementations of SDD systems. The S/N molar ratios should be controlled in a 5/3 to 5/2 range and HS−/S2− concentration should be

Microbial oxidation by bacteria with the potential to oxidize C1 compounds (methanotrophs) is the only biological sink for atmospheric methane (CH4). Aerobic methanotrophs are particularly active in forest soils, but the role of aerobic methanotrophs in native forest soils in China remains poorly understood. The pmoA gene, encoding the key enzyme methane monooxygenase (particulate MMO), is widely used to identify methanotrophic communities. We collected soils from different vegetation types in one subtropical and one temperate forest in China. Potential CH4 oxidation rates and methanotroph communities were assessed via laboratory incubation and pmoA-based phylogenetic analysis, respectively. Across all sampling sites, we observed distinct variations in methanotroph community composition and CH4 oxidation rates. In all soils, CH4 oxidation rates increased with increasing CH4 concentration. Elevated temperature resulted in an increase in the CH4 oxidation rates in coniferous forests, while a decrease in deciduous forests. Restriction fragment length polymorphism analyses indicated that methantrophic community varied in different vegetation types. The methanotroph communities were dominated by type II methanotrophs (including soil cluster alpha (SCα), Methylocystis, and USCα) and type I methanotrophs (including USCγ and Methylobacter) in deciduous and coniferous forests, respectively. It is suggested that intrinsic differences in CH4 oxidation rate responses to temperature between coniferous and deciduous soils are likely due to different methanotroph community structures. Taken together, the direction of CH4 feedback responses to disturbance was site specific.

The aim of this work was to study the acetate separation from fresh vinegar residue (FVR) to avoid inhibition of methanogenesis and hydrothermal treatment on washed vinegar residue (WVR) to enhance methane production. The optimal liquid-solid ratio was 10:1mL/g for the washing of FVR. The methane yields of the FVR, WVR, and washed leachate (WL) were 273L/kgVS, 199L/kgVS, and 306.9L/kgCOD, respectively. The optimal hydrothermal temperature was 160°C for WVR, with maximum methane yield of 258.38L/kgVS. Hydrothermal pretreatment destroyed the structure of lignocellulose and improved the hydrolysis of hemicellulose. Compared with thermophilic digestion of FVR, thermophilic digestion of 160°C treated FVR, and thermophilic digestion of WVR with mesophilic digestion of WL, the thermophilic digestion of 160°C treated WVR with mesophilic digestion of WL obtained the maximum total methane yield of 102.5L/kgFVR.

Metagenomic sequencing, basing on whole genomic analysis, was carried out to explain the taxonomic and functional patterns of microbial communities in co-digestion and mono-digestions with corn straw and pig manure. Bacteroides graminisolvens and Clostridium stercorarium, the dominant species for corn straw degradation, and Proteiniphilum acetatigenes, emphasizing on protein decomposition, performed the optimum abundance during the co-digestion to improve efficiency of substrate decomposition. Methanosaeta concilii was the richest species during the process of bio-methane production, whose quantity and status in co-digestion were better than in mono-digestion. Analysis of functional patterns indicated that the carbohydrate-active enzymes in co-digestion were sustained abundant resulting short lag time, and the abundance of enzymes involving in methanogenesis were extremely high in co-digestion indicating the active methane metabolism. An adequate understanding of taxonomic and functional patterns further revealed the mechanism of rapid startup and superb methane production in co-digestion.

As a new bioremediation technology for toxic metals, microbiologically induced calcite precipitation (MICP) is gradually becoming a research focus. This study investigated the application of MICP to mineralize toxic metals (lead and cadmium) in landfill leachate for the first time. In the experiment of remediating synthetic landfill leachate (SLL) contaminated by Pb2+, 100% of the 20 mg/L Pb2+ was removed when the maximum urease activity was only 20.96 U/ml. Scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) and laser particle size characterizations of the precipitates indicate the formation of agglomerated square particles, 76.9% of which had sizes that ranged from 33.93 to 57.06 μm. Fourier transform infrared spectroscopic and X-ray diffraction analyses confirmed that the precipitates consisted predominantly of calcite crystals, and the unit cell lattice constants of the precipitates (a = b = 4.984 A, c = 17.171 A) matched those of calcite, while lead was fixed as hydrocerussite. In addition, the Pb-MICP precipitates were stable under continuous acid degradation (pH = 5.5), and only 1.76% of the lead was released after 15 days. In the verification test of toxic metals remediation in a real landfill leachate (RLL), all of the Pb2+ and Cd2+ (initial concentrations: Pb2+ = 25 mg/L; Cd2+ = 5.6205 mg/L) was mineralized simultaneously, which further confirmed the feasibility of MICP for toxic metal remediation in landfill leachate. However, optimizing the urea dosage and combining the ammonium recovery are necessary strategies required for improving the economic and environmental benefits of the MICP process.

In this study, to efficiently remove malodorous gas and reduce secondary pollution under mixotrophic conditions, pine bark, coal cinder, straw and mobile bed biofilm reactor (MBBR) fillers were used as packing materials in a biological trickling filter (BTF) to simultaneously treat high-concentration H2S and NH3. The results showed that the removal rate of BTF-A filled with pine bark was the highest, which was 86.31% and 94.06% under the H2S and NH3 loading rates of 53.59 g/m³·h while the empty bed residence time (EBRT) was 40.5 s. The theoretical maximum load was obtained by fitting the kinetic curve, and the value were 90.09 g H2S m-³·h−1 and 172.41 g NH3 m-³·h−1. Meanwhile, after treating with 720 ppm of NH3, the average concentration of NO3- in the BTF circulating fluid was only 127.58 mg/L, indicating the better performance of secondary pollutants control. Microbiological analysis showed that Dokdonella, Micropruina, Candidatus_Alysiosphaera, Nakamurella and Thiobacillus possessed high abundance at the genus level, and their entire percentage in four BTF reactors were 62.87%, 46.32%, 47.98%, and 57.35% respectively. It is worthwhile that the genera Comamonas and Trichococcus with heterotrophic nitrification and aerobic denitrification capabilities and proportion of 3.66%, 1.45%, 5.43%, and 3.23% were observed in four reactors.

Microbial fuel cell (MFC) is a promising device for energy generation and organic waste treatment simultaneously by electrochemically active bacteria (EAB). In this study, an integrated aerobic-anaerobic strategy was developed to improve the performance of P. aeruginosa-inoculated MFC. With an aerobic start-up and following an anaerobic discharge process, the current density of MFC reached a maximum of 99.80µA/cm2, which was 91.6% higher than the MFC with conventional constant-anaerobic operation. Cyclic voltammetry and HPLC analysis showed that aerobic start-up significantly increased electron shuttle (pyocyanin) production (76% higher than the constant-anaerobic MFC). Additionally, enhanced anode biofilm formation was also observed in the integrated aerobic-anaerobic MFC. The increased pyocyanin production and biofilm formation promoted extracellular electron transfer from EAB to the anode and were the underlying mechanism for the MFC performance enhancement. This work demonstrated the integrated aerobic-anaerobic strategy would be a practical strategy to enhance the electricity generation of MFC.

This study investigated methane productions and the microbial communities in the batch anaerobic digestion process with the mono-digestion of corn stalk (CS) and pig manure (PM), and the co-digestion of them. Co-digestion showed the best methane performance, the cumulative methane yield, 256.57 mL·gVS −1 ; methane production potential, 281.55 mL·gVS −1 ; maximum methane production rate, 10.17 mL·d −1 ·gVS −1 ; and lag phase, 4.24 d. Moreover, co-digestion achieved a more suitable microenvironment including pH, FA and FVFA compared to mono-digestions. Results of high-throughput sequencing indicated that in co-digestion the dynamic changes of relative abundances of phyla and predominant genera were very small and community structure presented a stable status. Acetoclastic pathway was the main biochemical pathway of methanogenesis in co-digestion and mono-digestion of PM, and the growth rate of Methanosaeta in co-digestion was higher. So suitable microenvironment in co-digestion resulted in high growth rate of methanogens and stable microbial community, and leaded to the high methane production.

The intensive use of triphenyltin chloride (TPTC) has caused serious environmental pollution. In this study, an effective method for TPTC degradation was proposed based on the Bio-Electron-Fenton process in microbial fuel cells (MFCs). The maximum voltage of the MFC with graphite felt as electrode was 278.47% higher than that of carbon cloth. The electricity generated by MFC can be used for in situ generation of H2O2 to a maximum of 135.96μmolL-1 at the Fe@Fe2O3(*)/graphite felt composite cathode, which further reacted with leached Fe2+ to produce hydroxyl radicals. While 100μmolL-1 TPTC was added to the cathodic chamber, the degradation efficiency of TPTC reached 78.32±2.07%, with a rate of 0.775±0.021μmolL-1h-1. This Bio-Electron-Fenton driving TPTC degradation might involve in SnC bonds breaking and the main process is probably a stepwise dephenylation until the formation of inorganic tin and CO2. This study provides an energy saving and efficient approach for TPTC degradation.

One-step hydroxylation of C-H (sp 2 ) of aromatic ring synchronized with the oxidation of C-H (sp 3 ) of side-chain of p -xylene to 2,5-dihydroxyterephathalic acid was performed using M-MCM-41 (M = Fe, Fe/Cu, Cu) as the catalysts. Cu-MCM-41 (Cu:Si = 1:100) catalyst exhibited good selectivity (73.0%) of 2,5-dihydroxyterephathalic acid and conversion (21.7%) of p -xylene using acetic acid and acetonitrile (V:V = 3:7) as the solvents at 80 °C for 5 h. The possible mechanism of the oxidation of p -xylene to 2,5-dihydroxyterephathalic acid was proposed and would guide us to design high performance catalyst for sp 2 and sp 3 C-H oxidation. This procedure is also expected to be an alternative method to Kolbe-Schmitt Process for the synthesis of o -hydrobenzoic acids and their derivatives.

In this study, a core-shell Fe@Co nanoparticles uniformly modified graphite felt (Fe@Co/GF) was fabricated as the cathode by one-pot self-assembly strategy for the degradation of vanillic acid (VA), syringic acid (SA), and 4-hydroxybenzoic acid (HBA) in the Bio-Electro-Fenton (BEF) system. The Fe@Co/GF cathode showed dual advantages with excellent electrochemical performance and catalytic reactivity not only due to the high electron transfer efficiency but also the synergistic redox cycles between Fe and Co species, both of which significantly enhanced the in situ generation of H2O2 and hydroxyl radicals ( OH) to 152.40 μmol/L and 138.48 μmol/L, respectively. In this case, the degradation rates of VA, SA, and HBA reached 100, 94.32, and 100%, respectively, within 22 h. Representatively, VA was degraded and ultimately mineralized via demethylation, decarboxylation and ring-opening reactions. This work provided a promising approach for eliminating typical recalcitrant organic pollutants generated by the pre-treatment of lignocellulose resources.

Nitrogen loss is the main problem in compost and controlling it is the key to the recovery and utilization of composted materials. This study systematically investigated the effect of nitrogen retaining microbial agent (NRMA) on nitrogen retention and the promotion of decay during manure composting and tested its effect on nitrogen conversion and bacterial community structure. During composting, various parameters were dynamically evaluated, including nitrogen loss and transformation, compost maturity and nutrient, microorganism population and bacteria community variation. Results showed that the inoculation of NRMA significantly reduced ammonia loss by 58.8% with 15 days shorter compost cycle. At the end of the composting, the total nitrogen (TN) and nitrate content of the experimental group were 23.3 g kg−1 and 4.5 g kg−1, 22.6% (p

With polyhedral spheres as the packing, a semi-pilot biological trickling filter reactor (BTF) inoculated by domesticated activated sludge is used to remove Hydrogen Sulphide (H2S) and Ammonia (NH3). The removal rate of H2S and NH3 by BTF was as high as 98.25% and 88.55%, and the maximum removal load was 84.57 g H2S m−3h−1 and 38.77 g NH3 m−3h−1 during the 61-day process. The inlet gas concentration ranges from 0 to 500 ppm, and the empty bed residence time (EBRT) is 31.8 s. When the EBRT reduced from 31.8s to 25.4s, the removal rate of H2S and NH3 decreased significantly, which was 67.21% and 81.36%, respectively. The results showed that EBRT significantly affected the removal rate of H2S and NH3. Microbial analysis indicated that Dokdonella, Ferruginibacter, Nitrosomonas, and Thiobacillus had high abundance at the genus level, showing that these genera play an important role in the degradation of H2S and NH3. When the optimized parameters applied to the on-site biogas residue compost, the removal rate of H2S and NH3 by BTF can reach 91.34%, which provides a feasible process for the deodorization project with compost.

Minerals are ubiquitous in the natural environment and have close contact with microorganisms. In various scenarios, microorganisms that harbor extracellular electron transfer (EET) capabilities have evolved a series of beneficial strategies through the mutual exchange of electrons with extracellular minerals to enhance survival and metabolism. These electron exchange interactions are highly relevant to the cycling of elements in the epigeosphere and have a profound significance in bioelectrochemical engineering applications. In this review, we summarize recent advances related to the effects of different minerals that facilitate the EET process and discuss the underlying mechanisms and outlooks for future applications. The promotional effects of minerals arise from their redox-active ability, electrical conductivity and photocatalytic capability. In mineral-promoted EET processes, various responses have concurrently arisen in microorganisms, such as stretching of electrically conductive pili (e-pili), upregulated expression of outer-membrane cytochromes (Cyts) and production of specific enzymes, and secretion of extracellular polymeric substances (EPSs). This review synthesizes the understanding of electron exchange mechanisms between microorganisms and minerals and highlights potential applications in development of renewable energy production and pollutant remediation, which are topics of particular significance to future exploitation of biotechnology.

In order to develop a time-saving method for determination of ultimate methane production, obtain the hydrolysis kinetic constant, and identify a determination method for the nonbiodegradable organic fraction of substrate (VSNB) of green and air-dried corn stover, the kinetics of methane production and hydrolysis were studied using batch tests. The results showed that the conventional first-order hydrolysis kinetic model was not suitable for describing the entire hydrolysis process of corn stover, because there were two first-order decay periods for hydrolysis of corn stover. The hydrolysis kinetic constants kH,1 and kH,2 of the first and second periods were 0.1701 and 0.0415 1/d for green stover and 0.1052 and 0.0360 1/d for air-dried stover. The value of VSNB could be obtained by the graphical method rather than by the hydrolysis kinetic model. The obtained VSNB contents were 12.9% and 24.7% of VS (volatile solid) for green and air-dried stover, respectively. The ultimate methane production and corresponding digestion time could be understood through the methane production kinetic model by digestion experiments within a short time. The ultimate methane productions were 347.1 and 319.4 mL/g based on VS and the corresponding digestion times were 69.2 and 182.3 days for green and air-dried stover, respectively.

Micro-aerobic and anaerobic fermentative hydrogen productions were carried out in bottle tests (150 mL) and scale-up bioreactors (10 L) using corn straw as a substrate. Hydrogen yield of 41.6 mL/g (volatile solid, VS) obtained from scale-up experiment with optimal oxygen addition of 0.28 mL/(g (total solid, TS)·day) was higher than that of 28.9 mL/g VS without additional oxygen. Oxidation reduction potential was−300∼−150 mV for micro-aerobic fermentation, where it was−560∼−360 mV for anaerobic fermentation. The micro-aerobic condition had strong buffering ability and could tolerate a greater accumulation of volatile fatty acid. Both micro-aerobic and anaerobic hydrogen production were butyric acid-type fermentation. Microbial community analysis indicated the presence of Citrobacter sp. and Escherichia sp., which were unique to micro-aerobic system, as well as classical Enterococcus, Bacteroides, Peptoclostridium, Clostridium genera that existed in both micro-aerobic and anaerobic fermentation.

Intimate coupling of microbial extracellular electron transfer (EET) and photoelectrochemical processes is an emerging research area with great potential to circumvent many disadvantages associated with traditional techniques that depend on independent microbial or photocatalysis treatment. Microbial EET processes involve microorganism oxidation of extracellular electron donors for respiration and synchronous reduction of extracellular electron acceptors to form an integrated respiratory chain. Coupled microbial EET-photoelectrochemical technologies greatly improve energy conversion efficiency providing both economic and environmental benefits. Among substitutes for semiconductor photocatalysts, cadmium sulfide nanoparticles (CdS NPs) possess several attractive properties. Specifically, CdS NPs have suitable electrical conductivity, large specific surface area, visible light-driven photocatalysis capability and robust biocompatibility, enabling them to promote hybrid microbial-photoelectrochemical processes. This review highlights recent advances in intimately coupled CdS NPs-microbial extracellular electron transfer systems and examines the mechanistic pathways involved in photoelectrochemical transformations. Finally, the prospects for emerging applications utilizing hybrid CdS NPs-based microbial-photoelectrochemical technologies are assessed. As such, this review provides a rigorous fundamental analysis of electron transport dynamics for hybrid CdS NPs-microbial photoelectrochemical processes and explores the applicability of engineered CdS NPs-biohybrids for future applications, such as in environmental remediation and clean-energy production.

Solid-state fermentation (SSF), using corn stalk and soybean meal as solid substrates, was carried out for the first time to produce poly-γ-glutamic acid (γ-PGA) by Bacillus amyloliquefaciens JX-6. Comparison for the yield of γ-PGA, characteristics of solid substrates, and changes of bacterial communities between sterilized and non-sterilized conditions was performed with an aim to find a cleaner and more efficient approach for producing γ-PGA. Changes to solid substrates occurred during fermentation, and non-sterilized SSF had a more significant effect on fermentation substrates. Analysis of bacterial communities showed that JX-6 had an excellent ability to produce γ-PGA. Sterilized SSF resulted in higher yield of γ-PGA, while non-sterilized SSF possessed a faster fermentation process. The latter could be more suitable and environmental-friendly for large-scale γ-PGA fermentation because of the advantages of time and cost savings. It is noted that the production of γ-PGA in this study was the highest in the literatures, indicating a successful bioconversion of agricultural waste into value-added products.

This work investigated the effects of different temperatures on methane production, kinetics, and microbial communities during solid-state anaerobic digestion (SS-AD) using rice straw. The results indicated that thermophilic anaerobic digestion led to the faster methane production (13.74 L/kg) and a shorter biogas production cycle (34 days) than mesophilic anaerobic digestion (5.48 L/kg, 58 days). SS-AD under thermophilic conditions resulted in more intense lignocellulose degradation and better fitting results. The species of microorganisms did not differ when the temperature was altered; however, the abundances of various phyla, particularly Firmicutes, differed. Overall, the findings suggested that thermophilic SS-AD had higher methanogenic efficiency and dramatically altered the structure of the microbial community during solid-state anaerobic digestion. Moreover, a potential effective strategy for agricultural waste management by SS-AD was proposed.

Nitrogen doping in combination with the brookite phase or a mixture of TiO2 polymorphs nanomaterials can enhance photocatalytic activity under visible light. Generally, nitrogen-dopedanatase/brookite mixed phases TiO2 nanoparticles obtained by hydrothermal or solvothermal method need to be at high temperature and with long time heating treatment. Furthermore, the surface areas of them are low (

This study investigated the possibilities of improving the biogasification from solid-state anaerobic digestion (SS-AD) of composting rice straw (RS) based on the optimized digestion temperature, initial substrate concentration (ISC) and C/N ratio. RS compounds, such as lignin, cellulose, and hemicellulose, were significantly degraded after composting. A significant interactive effect of temperature, ISC and C/N ratio was found on the biogasification of SS-AD of composting RS, and a maximum biogas production was achieved at 35.6°C, with a 20% ISC and a C/N ratio of 29.6:1. The verification experiment confirmed the optimization results. High-throughput sequencing analysis indicated that microbial communities in the SS-AD mainly consist of Methanobacteria, Bacteroidia, Clostridia, Betaproteobacteria, and Gammaproteobacteria. A dominant Methanobacteria was shifted from Methanobacterium to Methanoculleus during the SS-AD process. This study provides novel information about the interdependent effects and microbial behavior of AD.

Although a few systems prepared by using biotemplates have been employed as mesoporous photocatalysts, the natural latex secreted by plants has not been used as a template to synthesize porous materials, let alone for the achievement of high photocatalytic activity under solar light. Herein, one of the most important biosynthesized polymers, natural rubber latex from the rubber tree, Hevea brasiliensis in Xishuangbanna was directly used as a structure-directing agent in synthesis of thermally stable mesostructured TiO2. The as-prepared samples were characterized by XRD, FT-IR, XPS, N2 adsorption/desorption, TEM and UV-vis DRS. The synthesized TiO2 exhibited highly effective photocatalytic activity for the degradation of phenol and rhodamine B under solar light. Furthermore, addition of acetylacetone (ACA) during the synthesis significantly enhanced the photocatalytic activity. The reported strategies provide a new direction of using natural rubber latex as a template to prepare highly effective photocatalysts.

Cobalt doped and undoped mesoporous titania were synthesized using resin acid as template. Moreover, without adding extra cobalt source, cobalt doped mesoporous titania was also synthesized by using cobalt resinate as both template and cobalt source. These mesoporous samples were characterized by a combination of various physicochemical techniques, such as N2 adsorption/adsorption isotherm, UV–vis diffuse reflectance, X-ray diffraction, high resolution transmission electron microscopy, XPS, and FT-IR. They were used for the photodegradation of methyl blue and Rhdamine B under visible light. It was found that P25 and mesoporous TiO2 synthesized using resin acid as template did not exhibit any meaningful activity for the photodegradation of two dyes under visible light. By contrast, cobalt doped mesoporous titania synthesized by using resin acid as template exhibited more significant photocatalytic yield (94%) for Rhdamine B. Moreover, cobalt doped mesoporous titania synthesized by using cobalt resinate as template also exhibited similar high photocatalytic activity for methyl blue to the former.

In this work, mesoporous TiO 2 compose of anatase and brookite phases (M-TiO 2 ) has been synthesized using 2,4,5-triphenylimidazole as template. The physical features of the as-prepared catalyst was measured by X-ray diffraction (XRD), low-temperature nitrogen adsorption/desorption, UV–visible diffuse reflectance spectrum, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The photocatalytic performance of the catalyst was evaluated in terms of the degradation of organic dyes. It is found that M-TiO 2 exhibits reasonable activity under UV light and can significantly degrade methylthionine chloride, rhodamine B, gentian violet, safranine T, methyl violet and fuchsine basic under visible-light irradiation ( λ ≥420 nm).

The use of metal-organic frameworks (MOFs) in the polymerization field remains comparatively rare up to now, let alone studies on the fabrication of polymer microstructures through a MOFs-catalyzed assembly process. Zeolitic imidazolate framework-8 (ZIF-8), a well-known MOF for its chemical and thermal stabilities, was used to induce a polymerization reaction of saturated alkylsilanes for the first time. The reaction temperature was found to be critical for morphology control of the polymerized ZIF-siloxane composites. The polymerization of alkylsilanes by ZIF-8 at room temperature resulted in siloxane microspheres while rose petal-like microstructures were obtained at higher temperature. The effects of the reaction time on the structures of the polymerization products were also investigated and the polymerization reaction process was proposed. This work expands the field of MOFs’ applications and develops a reasonable method for the multidimensional assembly of MOFs building blocks into required structures or platforms for designing new kinds of hierarchical morphologies, which to our knowledge has not been previously investigated.

Production of upgraded biogas is required to remove as much carbon dioxide as possible. It was found that by coupling microbial electrolysis cell (MEC) and anaerobic digestion (AD) in a single-chamber, barrel-shape stainless steel reactor, compared with common anaerobic digestion (control), CH4 content in excess of 98% was achieved and CH4 yield was increased 2.3 times. Meanwhile, the COD removal rate was tripled and carbon recovery was increased by 56.2%. In this new process, unwanted CO2 was in situ converted into CH4 on anode by the dominant microbes, hydrogenotrophic electromethanogens (e.g. Methanospirillum). These microbes could utilize hydrogen gas generated at the inner surface of stainless steel reactor, which itself served as cathode of MEC through small voltage addition (1.0 V). The overall energy efficiency was 66.7%. Keywords: Upgraded biogas, Carbon dioxide, MEC–AD coupling system, Stainless steel reactor

Liquid-phase catalytic oxidation of limonene was carried out under mild conditions, and carvone was produced in the presence of ZIF-67(Co), cobalt based zeolitic imidazolate framework, as catalyst, using t-butyl hydroperoxide (t-BHP) as oxidant and benzene as solvent. As a heterogeneous catalyst, the zeolitic imidazolate framework ZIF-67(Co) exhibited reasonable substrate&ndash, product selectivity (55.4%) and conversion (29.8%). Finally, the X-ray diffraction patterns of the catalyst before and after proved that ZIF-67(Co) acted as a heterogeneous catalyst, and can be reused without losing its activity to a great extent.

In sharp contrast to conventional photosensitization methods in which the organic pigments were often adsorbed, herein we present a study on natural vegetable pigment inserted TiO2 aerogel nanocomposites and we directly use red cabbage anthocyanin (RCP) as a structure-directing agent. It was found that pure TiO2 aerogel nanocomposite did not exhibit any meaningful activity for photocatalytic reduction of Cr(VI). However, the photocatalytic reduction activity was greatly improved by the RCP inserted TiO2 aerogel nanocomposites under visible-light irradiation, which was approximately 2- and 12.3-fold higher than that of TiO2 aerogel conventionally photosensitized by RCP and pure TiO2 aerogel nanocomposites, respectively. It also exhibited good stability and could be reused at least three times without losing a significant amount of its activity.

The siliceous frustules with sophisticated optical structure endow diatoms with superior solar light-harvesting abilities for effective photosynthesis. The preserved frustules of diatom (Cocconeis placentula) cells, as biophotonic crystals, were thus employed as both hard templates and silicon resources to synthesize TiO2 photocatalyst. Characterizations by a combination of physicochemical techniques proved that the bio-inspired sample is TiO2-coated SiO2 with biogenic C self-doped in. It was found that the synthesized composites exhibited similar morphologies to the original diatom templates. In comparison with commercial Degussa P25 TiO2, the C-doped TiO2/SiO2 catalyst exhibited more light absorption in the visible region and higher photocatalytic efficiency for photodegradation of rhodamine B under visible light due to the biomorphic hierarchical structures, TiO2 coating and C-doping.

With the transition of livestock production from the traditional small household farming to large-scale centralized breeding, the odor pollution caused by livestock manure has become pressing in China. In this study, two yeast strains Y1 and Y2 with high deodorization efficiency were isolated from the sample collected from an outlet in a swine farm in Shuangliu County, Sichuan Province. The scale-up deodorization experiments were carried out for strains Y1, Y2, and their mixture Y1+Y2. The results showed that the reduction rate of treatments on NH3 was in the sequence of Y1+Y2 (35.6 ∼ 68.7%) >Y1 (20.3 ∼ 63.7%) >Y2 (−11.7 ∼ 53.8%). The reduction rate of treatments on H2S was in the sequence of Y1+Y2 (47.2 ∼ 70.1%) > Y2 (36.6 ∼ 60.8%) > Y1 (27.6 ∼ 42.0%). The reduction rate of treatments on total volatile organic compounds (TVOC) was in the sequence of Y1+Y2 (49.1 ∼ 68.3%) > Y1 (36.2 ∼ 54.6%) >Y2 (20.8 ∼ 48.6%). The reduction rate of treatments on odor intensity was in the sequence of Y1+Y2 (27.2–60.3%) > Y1 (16.3 ∼ 38.5%) >Y2 (−0.4 ∼ 35.2%). Furthermore, the concentrations of VFAs, indole, skatole, total nitrogen (TN), organic nitrogen (ON), total sulfur (TS), and ammonium nitrogen (AN) in swine manure during deodorization by yeast strains Y1, Y2, and their mixture Y1+Y2 were assayed. The results showed the concentrations of VFAs, indole, and skatole in the manure with Y1, Y2, and Y1+Y2 treatments were all lower than those of the control group. The concentrations of TN, ON, and TS in treatments were all higher than that of the control group. The concentrations of AN in the treatment groups were all lower than those of the control group.

Odor pollution is a big environmental problem caused by large-scale livestock production in China, and developing a practical way to reduce these odors is pressing. In this study, a combination of 0.2-1.0 U/mL lignin peroxidase (LiP) and one of three peroxides (H2O2, CaO2, 2Na3CO3·3H2O2) was examined for its efficiency in reducing the release of eight chemicals (propionic acid, isobutyric acid, isocaproic acid, isovaleric acid, phenol, p-cresol, indole, and skatole), NH3, H2S, and odor intensity from pig manure. The results showed an approximately 90% reduction in p-cresol, 40-60% reduction in odor intensity, 16.5-40% reduction in indolic compounds, and 25-40% reduction in volatile fatty acids. Being the electron acceptors of LiP, 2Na3CO3·3H2O2 and CaO2 performed better than H2O2 in reducing the concentration of eight chemicals, NH3, H2S, and odor intensity from pig manure. The effect of deodorization can last for up to 72 hr.In China, one of the major environmental problems caused by confined feeding is odor pollution, which brings a major threat to the sustainability, profitability, and growth of the livestock industry. To couple the LiP with the electron acceptors, a low-cost, simple, and feasible method for odor removal was established in this study. Based on the study results, a practical treatment method was provided for odor pollution and supply the farm operators a more flexible time to dispose treated manure.