A novel strategy of artificially regulating plant rhizosphere microbial community to promote plant tolerance to cold stress.

Artificial regulation of plant rhizosphere microbial communities through the synthesis of microbial communities is one of the effective ways to improve plant stress resistance. However, the process of synthesizing stress resistant microbial communities with excellent performance is complex, time-consuming, and costly. To address this issue, we proposed a novel strategy for preparing functional microbial communities. We isolated a cultivable cold tolerant bacterial community (PRCBC) from the rhizosphere of peas, and studied its effectiveness in assisting rice to resist stress. The results indicate that PRCBC can not only improve the ability of rice to resist cold stress, but also promote the increase of rice yield after cold stress relieved. This is partly because PRCBC increases the nitrogen content in the rhizosphere soil, and promotes rice's absorption of nitrogen elements, thereby promoting rice growth and enhancing its ability to resist osmotic stress. More importantly, the application of PRCBC drives the succession of rice rhizosphere microbial communities, and promotes the succession of rice rhizosphere microbial communities towards stress resistance. Surprisingly, PRCBC drives the succession of rice rhizosphere microbial communities towards a composition similar to PRCBC. This provides a feasible novel method for artificially and directionally driving microbial succession. In summary, we not only proposed a novel and efficient strategy for preparing stress resistant microbial communities to promote plant stress resistance, but also unexpectedly discovered a possible directionally driving method for soil microbial community succession.

Collaboration of bacterial consortia for biodegradation of high concentration phenol and potential application of machine learning.

Mixed culture of microorganisms is an effective method to remove high concentration of phenol in wastewater. At present, it is still a challenge for microorganisms to remove high-concentration phenol from wastewater. In this study, a phenol-degrading consortium was isolated, which could rapidly degrade 1800 mg/L phenol within 30 h, and the highest phenol degradation concentration was 2000 mg/L. Further exploration of how microbial consortium cooperates to promote phenol biodegradation was studied: the core bacteria of the microbial consortium was relatively stable during phenol degradation; the bacteria could improve the adaptability to environment and metabolic ability of phenol, by producing more surfactants and betaine, thereby improving the degradation rate. The determination coefficient (R2) in the machine learning model showed that the back propagation artificial neural network (BP-ANN) can predict the biodegradation of phenol under different conditions, saving time and economic costs. This study explains how microbial consortium cooperates to degrade phenol from the aspects of microbial consortium composition and metabolic analysis, which provides a theoretical basis for mixed culture microorganisms to degrade pollutants.

Biomimetic Frustrated Lewis Pair Catalysts for Hydrogenation of CO to Methanol at Low Temperatures.

The industrial production of methanol through CO hydrogenation using the Cu/ZnO/Al2O3 catalyst requires harsh conditions, and the development of new catalysts with low operating temperatures is highly desirable. In this study, organic biomimetic FLP catalysts with good tolerance to CO poison are theoretically designed. The base-free catalytic reaction contains the 1,1-addition of CO into a formic acid intermediate and the hydrogenation of the formic acid intermediate into methanol. Low-energy spans (25.6, 22.1, and 20.6 kcal/mol) are achieved, indicating that CO can be hydrogenated into methanol at low temperatures. The new extended aromatization-dearomatization effect involving multiple rings is proposed to effectively facilitate the rate-determining CO 1,1-addition step, and a new CO activation model is proposed for organic catalysts.

Unveiling Pre-Transmetalation Intermediates in Base-Free Suzuki-Miyaura Cross-Couplings: A Computational Study.

The pre-transmetalation intermediates are critically important in Suzuki-Miyaura cross-coupling (SMC) reactions and have become a hot spot of the current research. However, the pre-transmetalation intermediates under base-free conditions have not been clear. Herein, a comprehensive theoretical study is performed on the base-free Pd-catalyzed desulfonative SMC reaction. The fragile coordination feature and the acceleration role of the RuPhos chelate ligand are revealed. The hydrogen-bond complex between the Pd-F complex and aryl boronic acid is identified as an important pre-transmetalation intermediate, which increases the energy span to 32.5 kcal/mol. The controlling factor for the formation of the hydrogen-bond complexes is attributed to the electronegativities of halogen atoms in the metal halide complexes. What is more, other reported SMC reaction systems involving metal halide complexes and aryl boronic acids are reconsidered and suggest that the hydrogen-bond complexes widely exist as stable pre-transmetalation intermediates with influencing the catalytic activities. The earth-abundant Ni-catalyzed desulfonative SMC reaction is further designed and predicted to have a higher activity than the original Pd-catalyzed SMC reaction.

Enhanced biodegradation of phenol by microbial collaboration: Resistance, metabolite utilization, and pH stabilization.

Mixed culture of microorganisms is an effective method to remove high concentration of phenol from wastewater. Currently, the mechanism of how microorganisms collaborate to enhance the biodegradation of phenol is still a challenge. In this study, the isolated Bacillus subtilis ZWB1 and Bacillus velezensis ZWB2 were co-cultured to enhance phenol biodegradation, and the mechanism of microbial collaboration was further explored. The co-culture of strains could significantly increase the rate (16.7 mg/L·h, 1000 mg/L) and concentration of phenol degradation (1500 mg/L), comparing with mono-culture of ZWB1 (4.2 mg/L·h, 150 mg/L) and ZWB2 (6.9 mg/L·h, 1000 mg/L), among which the highest degraded concentration of phenol for ZWB1 and ZWB2 was 150 and 1000 mg/L. Further, the mechanism of microbial collaboration to enhance phenol biodegradation was raised: the decrease of antioxidant enzymes, and increase of degrading enzymes and surfactants on content after co-culture, assisted the microorganisms in withstanding phenol; Bacillus subtilis ZWB1 used the metabolites of Bacillus velezensis ZWB2 to promote its growth, and further to degrade phenol rapidly; Bacillus subtilis ZWB1 alleviated the damage, which resulted from the pH drop (5.8) of the fermentation broth during phenol degradation that inhibited the growth and degraded ability of Bacillus velezensis ZWB2, making the pH of fermentation broth stable at 7. Metabolic analysis showed that co-culture of strains could produce more alkaline and buffering compounds and pairs, to stabilize pH and reduce the toxicity of acidity on ZWB2, thus increasing the degradation rate. This study explains the mechanism of microbial collaboration on phenol biodegradation from multiple perspectives, especially pH stabilization, which provides a theoretical basis for the degradation of pollutants by co-culture microorganisms.

Ce(IV)-Based Metal-Organic Gel for Ultrafast Removal of Trace Arsenate from Water.

As a potential replacement for metal-organic frameworks (MOFs), constructing metal-organic gels (MOGs) is an appealing but challenging topic since MOGs are a kind of shapeable MOF gels. Also, the rapid adsorption of trace heavy metal ions in aqueous media remains a serious challenge. Herein, a simple strategy for the synthesis of Ce(IV)-based metal-organic gel (Ce-MOG) was first developed for the rapid adsorption of trace As(V). The (NH4)2Ce(NO3)6 obtains hydroxide bridges after adding apposite NaOH, leading to [Ce6O4(OH)4]12+ clustering and inducing fast and excessive nucleation rates, which also leads to coordination disturbance of MOF nanocrystals to obtain Ce-MOG. The Ce-OH groups are the key to gel formation through hydrogen bonding and are the active site for the ultrafast adsorption of As(V). As expected, the resultant Ce-MOG has an excellent adsorption rate, making it possible to effectively decontaminate 500 ppb of As(V) to below the World Health Organization (WHO) recommended threshold for drinking water (10 ppb) within 1 min. It achieves equilibrium adsorption in 10 min, and the final arsenate-removing efficiency reaches 99.8%. For Ce-MOF, the effluent concentration of As(V) is higher than the drinking water standard, while equilibrium adsorption takes 60 min. The initial adsorption rate of Ce-MOG, h(k2qe2) is calculated and indicated to be 67.67 mg g-1 min-1, about 19.96 times that of Ce-MOF (3.39 mg g-1 min-1). As such, the excellent As(V) decontamination rate, selectivity, and reusability of Ce-MOG indicate its great potential for practical drinking water purification.

Low acyl gellan gum immobilized Lactobacillus bulgaricus T15 produce D-lactic acid from non-detoxified corn stover hydrolysate.

Straw biorefinery offers economical and sustainable production of chemicals. The merits of cell immobilization technology have become the key technology to meet D-lactic acid production from non- detoxified corn stover. In this paper, Low acyl gellan gum (LA-GAGR) was employed first time for Lactobacillus bulgaricus T15 immobilization and applied in D-lactic acid (D-LA) production from non-detoxified corn stover hydrolysate. Compared with the conventional calcium alginate (E404), LA-GAGR has a hencky stress of 82.09 kPa and excellent tolerance to 5-hydroxymethylfurfural (5-HMF), ferulic acid (FA), and vanillin. These features make LA-GAGR immobilized T15 work for 50 days via cell-recycle fermentation with D-LA yield of 2.77 ± 0.27 g/L h, while E404 immobilized T15 can only work for 30 days. The production of D-LA from non-detoxified corn stover hydrolysate with LA-GAGR immobilized T15 was also higher than that of free T15 fermentation and E404 immobilized T15 fermentation. In conclusion, LA-GAGR is an excellent cell immobilization material with great potential for industrial application in straw biorefinery industry.

Facile green preparation of single- and two-component modified activated carbon fibers for efficient trace heavy metals removal from drinking water.

Trace heavy metals exist in drinking water, having great adverse effects on human health and making it a huge challenge to remove. Herein, novel materials have been prepared by a simple and green method using single- (polydopamine (PDA) or 2,3-dimercaptopropanesulfonic sodium (DMPS)) (PDA-OACF or DMPS-OACF) and two-component (PDA and DMPS) (DMPS-PDA-OACF) functionalized activated carbon fibers pretreated by hydrogen peroxide for the removal of trace heavy metals. The as-prepared DMPS-OACF (7.5,20) under DMPS addition of 7.5 mg and sonication time of 20 min retained large specific surface area, micro-mesoporous structure and rich functional groups and showed better adsorption performance for trace lead and mercury. It also exhibited wide applicable ranges of pH (3.50-10.50) and concentration (50-1136 µg L-1), rapid adsorption kinetics, and excellently selective removal performance for trace lead. The maximum lead adsorption capacity reached 16.03 mg g-1 when the effluent lead concentration met World Health Organization (WHO) standard and the adsorbent can be regenerated by EDTA solution. The fitting results of adsorption kinetics and isotherm models revealed that the lead adsorption process was multi-site adsorption on heterogeneous surfaces and chemical adsorption. The excellent adsorption properties for trace heavy metals were attributed that the sulfur/oxygen/nitrogen-containing functional groups boosted diffusion and adsorption by electrostatic attraction and coordination, suggesting that DMPS-OACF (7.5,20) has great application potential in the removal of trace heavy metals.

Enhancing quinoa growth under severe saline-alkali stress by phosphate solubilizing microorganism Penicillium funicuiosum P1.

Promoting the growth of plants and improving plant stress-resistance by plant growth-promoting microorganism increasingly become a hotpot. While, most researchers focus on their supply role of nutrition or plant hormone. In this study, a novel mechanism that phosphate solubilizing microorganisms promoted plant growth under saline-alkali stress through secretion of organic acids, was proposed. The effects of desulfurization gypsum, humic acid, organic fertilizer and phosphate-solubilizing microorganism Penicillium funicuiosum P1 (KX400570) on the growth of quinoa (Chenopodium quinoa cv. Longli 1), showed that the survival rate, stem length and dry weight of quinoa treated with P1 were 2.5, 1.5, 1 and 1.5 times higher than those of sterile water (CK) under severe saline-alkali stress. The growth-promoting effect of P1 on quinoa was much better than that of other treatment groups. In addition, P1 promoted the growth of quinoa because the organic acids (malic acid, citric acid, succinic acid, etc.) from P1 stimulated the antioxidant system and promote the photosynthesis of quinoa, further promote quinoa growth.

A study of highly efficient phenol biodegradation by a versatile Bacillus cereus ZWB3 on aerobic condition.

As one of the organic pollutants in industrial wastewater, phenol seriously threatens the environment and human health. Among various methods, microbial degradation of phenol possesses the advantages of nontoxicity and no secondary pollution. Therefore, search for microbial resources that can efficiently degrade phenol has become an important issue. In this study, a strain that could efficiently degrade phenol was isolated. The strain was identified as Bacillus cereus based on its morphology, physiological and biochemical features and 16S rRNA sequence analysis. The strain can completely degrade phenol up to 1,500 mg/L within 26 h (57.7 mg·L-1·h-1), under the optimum conditions, faster compared with the known degrading bacteria. The strain could efficiently remove phenol at a wide range of temperatures (22-37 °C) and pH (7-9), and Mn2+ and Zn2+ stress. Interestingly, this strain displayed the potential on microthermal environment, which could degrade 1,200 mg/L phenol within 36 h at 22 °C. Further, the strain had capacity that used a variety of aromatic compounds as the sole carbon source for growth. This study shows a useful biodegradation route on the wastewater treatment under high phenol concentration conditions, providing alternatives for environmental remediation.

Enhanced degradation of phenol by a novel biomaterial through the immobilization of bacteria on cationic straw.

As phenol possesses a threat to human health, there is a great demand to search for fast and efficient methods for it to be discharged. In this study, a novel biomaterial was prepared by the immobilization of bacteria on a cationic straw carrier, and the remediation ability of the biomaterial on phenol-containing wastewater was investigated. The free bacteria could degrade 1,000 mg/L phenol within 240 h, while the prepared biomaterial was 192 h, shortening by 48 h that of free bacteria. In addition, the degradation tolerance of biomaterial increased from 1,000 mg/L to 1,200 mg/L than the free bacteria, within 216 h, which shortened by 24 h the degradation time of 1,000 mg/L phenol by free bacteria (240 h). Further, under different pH conditions, the degradation efficiency of phenol by prepared biomaterial was much higher than that of free bacteria. Especially for the lower pH 5, the degradation efficiency of biomaterial was nearly twice that of the free bacteria. This investigation demonstrates that this biomaterial has great potential in the field of remediation of organic pollution.

Prevalence and risk factors for bone loss in rheumatoid arthritis patients from South China: modeled by three methods.

BACKGROUND: To explore the prevalence of bone loss among patients with rheumatoid arthritis (RA) and healthy controls (HC) and further explored the risk factors for osteopenia and osteoporosis of RA patients. METHODS: A cross-sectional survey was undertaken in four hospitals in different districts in South China to reveal the prevalence of bone loss in patients. Case records, laboratory tests, and bone mineral density (BMD) results of patients were collected. Traditional multivariable logistic regression analysis and two machine learning methods, including least absolute shrinkage selection operator (LASSO) and random forest (RF) were for exploring the risk factors for osteopenia or osteoporosis in RA patients. RESULTS: Four hundred five patients with RA and 198 HC were included. RA patients had lower BMD in almost BMD measurement sites than healthy controls; the decline of lumbar spine BMD was earlier than HC. RA patients were more likely to comorbid with osteopenia and osteoporosis (p for trend < 0.001) in the lumbar spine than HC. Higher serum 25-hydroxyvitamin D3 level and using tumor necrosis factor inhibitor in the last year were protective factors; aging, lower body mass index, and increased serum uric acid might be risk factors for bone loss. CONCLUSIONS: RA patients were more prone and earlier to have bone loss than HC. More attention should be paid to measuring BMD in RA patients aging with lower BMI or hyperuricemia. Besides, serum vitamin D and all three measurement sites are recommended to check routinely. TNFi usage in the last year might benefit bone mass.

Mixed lead source precursors for producing light absorption layers of perovskite solar cells.

Beside the conventional perovskite precursors with lead halides as lead sources, non-halide lead sources provide additional tools for tuning the properties of perovskite layers, and lead acetate is a promising candidate for non-halide lead sources. In this work, we develop the perovskite precursor with a mixed non-halide lead source by partially replacing lead acetate with lead thiocyanate. Scanning electron microscopy and X-ray diffraction measurements indicate that lead thiocyanate additive can remarkably increase the size of perovskite grains and the crystallization of perovskite layers. And the cross-sectional investigation illustrates that the penetration of perovskite materials into TiO2 porous layers also can be improved by the lead thiocyanate additive. As a consequence, the recombination process and charge extraction process of devices are improved. By optimizing the quantity of lead thiocyanate, the power conversion efficiency of devices is increased from 14.0% to 17.2%, and the stability of devices is elevated simultaneously.

Mono-Dispersed Microspheres Locally Assembled on Porous Substrates Formed through a Microemulsion Approach.

A cost-effective, simple, and time-saving method to fabricate mono-dispersed periodic microsphere structures on substrates with patterned sites is very meaningful due to their significance on various biological studies. Herein, a simple and facile method to fabricate mono-dispersed microsphere arrays on porous substrates was developed. The mixture of polystyrene and an organic stabilizer solution which contains aqueous solution, fabricated through shaking, was applied to prepare microemulsion solution. An ordered porous structure was produced by spreading and evaporating the solvent of microemulsion on a glass slide, accompanied by the enrichment of didodecylamine in the cavities. The porous cavities were further modified with polyacrylic acid and poly(diallyldimethylammonium chloride) which could immobilize the microspheres. The charged microspheres were incorporated into the cavities by an electrostatic interaction with the oppositely charged polyelectrolytes. The positive polyelectrolytes with abundant charges as well as a suitable content and dimension of microspheres, ensured the formation of mono-dispersed and ordered arrays. Considering that other charged particles were universally suitable for the present strategy, the reported approach opened an efficient way for the preparation of microsphere-based materials.

Efficient adsorption and full spectrum photocatalytic degradation of low concentration PPCPs promoted by graphene/TiO2 nanowires hybrid structure in 3D hydrogel networks.

The removal of low concentration PPCPs from water is a challenging issue. A graphene hydrogel with 3D networks shows great potential for accelerating eddy diffusion of low concentration PPCPs. Herein, to further promote its molecular diffusion, a graphene/TiO2 nanowires (GNW) hybrid structure was implanted into graphene hydrogel. The as-prepared rGO/GNW hydrogel exhibited significantly enhanced adsorption-photocatalytic performance and excellent stability for low concentration ethenzamide, a typical pharmaceutical pollutant in water, under vacuum ultraviolet (VUV), ultraviolet (UV), visible and near-infrared light irradiation. When the initial ethenzamide concentration was 500 ppb and catalyst dosage was 10 mg/150 mL, ethenzamide was completely removed in 3 min and the corresponding photocatalytic apparent rate constant was 2.20 times that by GNW, 4.09 times that by rGO/P25 and 4.31 times that by rGO/NW under VUV irradiation, respectively, and its removal rate attained 99.0% in 120 min and the corresponding photocatalytic apparent rate constant was 2.06 times that by GNW, 3.34 times that by rGO/P25 and 17.42 times that by rGO/NW under UV irradiation, respectively. The GNW hybrid structure in the hydrogel played a vital role in overcoming the mass transfer resistance of low concentration PPCPs. The as-prepared rGO/GNW hydrogel exhibits significant potential for the removal of low concentration PPCPs from water.

Self-organized nanocrystal rings formed by microemulsion for selective recognition of proteins and immunoassays.

A simple and cheap method to fabricate a nanocrystal ring pattern was developed by utilization of a microemulsion in this study. The mixture of polystyrene and stabilizer dichloromethane solution that contained nanocrystal aqueous solution, prepared through shaking, was applied to fabricate a reverse microemulsion. After spreading and evaporating the solvent of microemulsion on a glass slide, an ordered honeycomb film was produced, accompanied by the formation of a nanocrystal ring pattern. The nanocrystal pattern could be readily applied for immunoassays and recognition of proteins. The pattern with antibody marked by a green colored nanocrystal specifically bound with antigen labeled by a red colored nanocrystal, leading to the enhancement in red fluorescent ring pattern and decrease in green fluorescent pattern. When the unlabeled antigen was added, the green fluorescent pattern was recovered. In addition, the ring pattern with immunocomplex could selectively recognize antigen and transferrin proteins. This strategy reveals that these patterns have potential applications in biochips, biosensors, imaging analysis and so forth.

Self-assembled quantum dot microstructure guided by a microemulsion approach for immunoassays.

Quantum dot microstructures were fabricated through a convenient microemulsion approach in this study. A polymer solution containing a stabilizer was mixed with a quantum dot aqueous solution, to prepare a reversed microemulsion, through shaking. Then, the microemulsion was cast on a solid substrate followed by evaporating steps, resulting in the formation of an ordered porous film. Interestingly, the quantum dot microstructure can be produced at the same time. The immunoassay experiment could be realized by the fluorescent microstructures. The green fluorescence microstructure specifically bound with antigens marked with red color quantum dots, resulting in the enhancement of red fluorescence domains and the decrease of green fluorescence. With the addition of unlabeled antigens, the green fluorescence microstructure was recovered. This strategy implies that the quantum dot pattern has potential on biochip, biosensor, and imaging analysis.

Assembly of heteropoly acid into localized porous structures for in situ preparation of silver and polypyrrole nanoparticles.

A simple and facile method to fabricate porous films which were locally patterned by heteropoly acid was developed in this study. The mixture of poly(methyl methacrylate) and stabilizer dichloromethane solution which contains heteropoly acid aqueous solution, prepared through shaking, was applied to fabricate a reversed microemulsion. After spreading and evaporating the solvent of microemulsion on a glass slide, an ordered honeycomb film was produced by incorporation of heteropoly acid in the cavities. The locally anchored heteropoly acid could be readily applied for the selective modification of the porous films through the in situ chemical reactions in the cavities with the additive agents. The silver nanoparticles were in situ prepared via the reduction of silver ions by reduced state H3PW12O40, and the polypyrrole spheres were locally obtained through the oxidative polymerization of pyrrole catalyzed by H3PMo12O40 in the cavities. Considering that water-soluble molecules and nanoparticles were universally suitable for the present strategy, the reported approach opened up an efficient way for patterning organically incompatible components on porous polymer films via the assembly of microemulsion droplet carriers to fabricate multi-functional hybrid surface structures.

The isolation and functional identification on producing cellulase of Pseudomonas mendocina.

The straw can be degraded efficiently into humus by powerful enzymes from microorganisms, resulting in the accelerated circulation of N,P,K and other effective elements in ecological system. We isolated a strain through screening the straw degradation strains from natural humic straw in the low temperature area in northeast of china, which can produce cellulase efficiently. The strain was identified as Pseudomonas mendocina by using morphological, physiological, biochemical test, and molecular biological test, with the functional clarification on producing cellulase for Pseudomonas mendocina for the first time. The enzyme force constant Km and the maximum reaction rate (Vmax) of the strain were 0.3261 g/L and 0.1525 mg/(min.L) through the enzyme activity detection, and the molecular weight of the enzyme produced by the strain were 42.4 kD and 20.4 kD based on SDS-PAGE. The effects of various ecological factors such as temperature, pH and nematodes on the enzyme produced by the strain in the micro ecosystem in plant roots were evaluated. The result showed that the optimum temperature was 28°C, and the best pH was 7.4∼7.8, the impact heavy metal was Pb2+ and the enzyme activity and biomass of Pseudomonas mendocina increased the movement and predation of nematodes.