BIOTECHNOLOGY AND APPLIED BIOCHEMISTRY
·
2024
·
IF 3.2
Qian Tan,Linbo Gou,Tai-Ping Fan,Yujie Cai
Clostridium aceticum DSM1496 is an acid-resistant strain in which ornithine decarboxylase (ODC) plays a crucial role in acid resistance. In this study, we expressed ODC derived from C. aceticum DSM1496 in Escherichia coli BL21 (DE3) and thoroughly examined its enzymatic properties. The enzyme has a molecular weight of 55.27 kDa and uses pyridoxal-5′-phosphate (PLP) as a coenzyme with a K m = 0.31 mM. ODC exhibits optimal activity at pH 7.5, and it maintains high stability even at pH 4.5. The peak reaction temperature for ODC is 30°C. Besides, it can be influenced by certain metal ions such as Mn 2+ . Although l -ornithine serves as the preferred substrate for ODC, the enzyme also decarboxylates l -arginine and l -lysine simultaneously. The results indicate that ODC derived from C. aceticum DSM1496 exhibits the ability to produce putrescine, cadaverine, and agmatine through decarboxylation. These polyamines have the potential to neutralize acid in an acidic environment, facilitating the growth of microorganisms. These significant findings provide a strong basis for further investigation into the acid-resistant mechanisms contributed by ODC.
研究领域:
微生物学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Zhuoya Hao,Jiacheng Zhang,Qin Peng,Xuefeng Tian,Jun Zhang,Jiayi Ai,Qiqi Jia,Yihui Yuan,Ning Wang
The increasing global reliance on nuclear energy highlights the critical need for uranium recovery from nuclear wastewater. However, due to the harsh environment of concentrated acid and nuclear radiation, the development of new adsorbent for uranium recovery from nuclear wastewater is highly needed. The bacterial spore has been reported to exhibit high tolerance to these harsh environments and contain functional components with reliable uranium binding ability, while there is still no report on the use of bacterial spore for uranium recovery from nuclear wastewater. Herein, the potential of the bacterial spore for being used in uranium recovery was analyzed for the first time. The result shows that the bacterial spore realizes a high uranium adsorption capacity of 245 mg g −1 in uranium-containing aqueous environment. With a low dosage of 0.1 g L −1 , the bacterial spore achieves a high uranium removal performance of 99.03 % in simulated nuclear wastewater. Additionally, when the concentration of HNO 3 reached 12 M, the adsorption capacity can still reach 156 mg g −1 after 24 h of treatment, proving its high tolerance to concentrated acid. Moreover, after being irradiated by γ-ray with the radiation dosage of 500 kGy, the bacterial spore retains 95.94 % of the uranium adsorption capacity, indicating its high resistance to nuclear radiation. These findings indicate that the bacterial spore would be a highly potential adsorbent for the recovery of uranium from nuclear wastewater with concentrated acid and nuclear radiation.
研究领域:
环境科学
·
微生物学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Yiman He,Yuping Zhang,Fan Liang,Yuzhang Zhu,Jian Jin
Desalination of seawater, brackish water and urban sewage is an important way to solve the global water shortage. Polyamide (PA) membranes, including reverse osmosis (RO) membrane and nanofiltration (NF) membrane, are the primary technology for seawater desalination and clean water production. However, traditional thin-film composite PA (TFC-PA) membranes prepared from interfacial polymerization (IP) of amine monomers (either piperazine or m-phenylenediamine) in water and acyl chloride monomers in organic solvent are incapable of tolerating strong acid and chlorine environment. Here, we develop a new IP process, which takes place at the immiscible interface between dimethylacetamide (DMAc) and hexane (referred to as organic/organic IP), to prepare both chlorine-resistant and acid-resistant TFC-PA membranes. Compared to conventional water/oil IP process, the organic/organic IP process can adapt more kinds of amine monomers rather than just PIP, such as tetra (4-aminophenyl) methane (TMAP), tris (4-aminophenyl) amine (TAPA), and 4,4′,4''-(1,3,5-triazine-2,4,6-triyl) triphenylamine (TTA), which we studied in this work, thereby extending the PA molecular structure and enabling the membranes with greatly improved chemical stability. Among them, the TAPM-based TFC-PA membrane exhibits a NaCl rejection of 95.9% and no obvious NaCl rejection deterioration after soaking in a high concentration of NaClO (1000 ppm, pH 7) for more than 30 h, indicating excellent chlorine resistance. The TTA-based TFC-PA membrane shows a Na 2 SO 4 rejection of 97% and remains unchanged after being exposed to a wide pH scan of 2–12. The Organic/organic IP provides a new and easy-to-operate platform for designing chlorine and acid resistant TFC-PA membranes, which will greatly improve their environmental stability as the most advanced desalination membrane at present.
研究领域:
材料科学
·
环境工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CARBON
·
2015
·
IF 6.196
Xiangdong Zhu,Feng Qian,Yuchen Liu,Daniel Matera,Gang Wu,Shicheng Zhang,Jianmin Chen
Facile fabrication of magnetic carbon composites (MCs) via pyrolysis of hydrochar in the presence of ZnCl 2 and an iron salt has been attracting enormous interest to simultaneously realize high-surface area and magnetization. During this synthesis, the interactions between the carbon matrix and iron salts have remained unknown. In this work, a closer look was taken on iron salt interactions and their respective effect on MC characteristics. These newly fabricated MCs can provide guidance for further design of efficient MCs. It was discovered that ferric chloride (FeCl 3 ) promoted the enhancement of MC porosity, largely due to the strong reduction reaction between amorphous carbon and iron oxide (γ-Fe 2 O 3 and Fe 3 O 4 ). Various other iron salts (including ferrous oxalate (FeC 2 O 4 ), ferric citrate (FeC 6 H 5 O 7 ), and ferric sulfate (Fe 2 (SO 4 ) 3 ) were also evaluated. These compounds inhibited pore structure development, resulting from decreased carbonization seen in the composite. This phenomenon was observed from complexation reactions between Zn 2+ and the corresponding anions of these salts. Also, high Fe content and low γ-Fe 2 O 3 :Fe 3 O 4 ratios led to decreased acid resistance of the MC. Finally, higher porosity in resultant MCs resulted in larger adsorption capacity for organic pollutants (roxarsone). This study will aid in further optimization of MCs to ultimately maximum performance.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
Journal of Pharmaceutical Investigation
·
2017
·Vol. 48
·期 3
·341-350
·
IF 0
Liu Jiang-Yan,Zhang Xiao-Xue,Huang Hao-Yan,Lee Beom-Jin,Cui Jing-Hao,Cao Qing-Ri
The aim of this study was to develop esomeprazole magnesium (EMZ-Mg) enteric-coated pellets and pellet-based tablets, as well as to investigate the effects of pellet size and compression method on acid tolerance, content uniformity, compressibility, and stability of preparations. This study used two types of pellet cores, namely, microcrystalline cellulose (MCC) core with a particle size of 150–300 μm and sucrose core with a particle size of 600–700 μm. Enteric-coated pellets, which consisted of a drug-free core, a drug layer, a sub-coating layer (hydroxypropyl methylcellulose, 6 cps), and an enteric-coating layer (Eudragit ® L30D-55), were prepared by using a bottom-spray fluidized bed-coating technique. Pellet-based tablets were prepared by using a direct compression method or a wet granulation method. The acid tolerances of the two types of enteric-coated pellets (MCC and sucrose cores) reached up to 98% in simulated gastric fluid (pH 1.0) within 2 h, and the dissolution rates in simulated intestinal fluid (pH 6.8) reached up to 85% of the labeled amount within 15 min. When compressed into tablets, the pellets based on MCC core (smaller particle size) displayed a significantly higher acid tolerance (up to 92%) compared with the pellets based on sucrose core (larger particle size). In addition, the MCC core-based tablets (F8), especially those prepared by using a granulation method, showed higher drug content uniformity and compressibility than the sucrose core-based tablets (F10), and no lamination phenomenon was observed during compression. The crystallinity of EMZ-Mg was altered during drug layering process, and some physicochemical interactions were observed between the drug and excipients. Moreover, the two types of enteric-coated pellets showed a relatively high stability after storage under high temperature and strong light. However, they showed poor stability under high humidity, resulting in remarkable degradation of active compound. The EMZ-Mg enteric-coated pellets and pellet-based tablets were successfully developed, and reduction in pellet size and wet granulation reduced the differences in content uniformity and better protected the pellet coating from damages during compression.
研究领域:
药剂学
·
药物开发
✓ 已验证
产品关联
DOI
Foodborne Pathogens and Disease
·
2020
·Vol. 17
·期 4
·253-261
·
IF 2.601
Yunge Liu,Lixian Zhu,Pengcheng Dong,Rongrong Liang,Yanwei Mao,Xiaoyin Yang,Yimin Zhang,Xin Luo
This study evaluated the acid tolerance response (ATR) of two strains of Listeria monocytogenes (serotype 1/2a and 4b) and one strain of Listeria innocua under different mildly acid conditions. Cells were incubated in combinations of three concentrations of lactic acid medium (3, 4.75, and 15 mM) and three external pH's (pHex 5.0, 6.0, and 6.5), plus, a HCl control, and a blank control (pH 7.4). Results showed that lactic acid induced lower log reduction of all three strains when challenged in severe acid conditions (pH 3.0) after being habituated at a pHex of 5.5 or 6.0 until the log phase, compared with a pHex of 6.5 or the two controls. This indicates that when the pHex was either 5.5 or 6.0 this induced a higher ATR of the strains, which may be caused by the ability of the strains to retain intracellular pH (pHi) homeostasis with pHi maintained in the range of 7.4–7.9. It was also found that a pHex of 5.5 resulted in the highest pHi of the strains across all incubated conditions, which indicates that the pHi may play an important role in the induction of ATR when Listeria cells are habituated in lactic acid, and if the higher pHi can be maintained, the ATR would be stronger. The concentration of lactic acid per se has no significant effect on ATR, which it is proposed was due to the pHi homeostasis maintained within the cells. However, the difference in ATR among three strains was also significant, which cannot be explained by the stable pHi of all tested strains. Therefore, other underlying mechanisms to mediate ATR under different conditions need to be explored in further studies.
研究领域:
微生物学
·
食品安全
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2019
·Vol. 9
·期 5
·1108-1116
·
IF 5.726
Liangliang Zhang,Xiao Chen,Yujing Chen,Zhijian Peng,Changhai Liang
Chemoselective hydrogenation of phthalic anhydride is regarded as the most promising route for producing downstream high-performance phthalide. A series of intermetallic cobalt–nickel silicide catalysts embedded in a carbon matrix (CoxNi2−xSi@C) with acid-tolerance prepared by microwave-assisted chemical vapor deposition have been investigated in this reaction system. Activity measurements show a remarkable positive synergistic effect, forming a volcano-shaped plot over the nominal Co metal fraction for CoxNi2−xSi@C catalysts with a peak at x = 1.5, which corresponds to a 4.5-fold enhancement of the yield of phthalide over Co2Si@C and a 2.0-fold enhancement over the Ni2Si@C monometallic silicide catalysts, which can be correlated with the interaction of cobalt–nickel and metal–silicon bonds. In addition, the cobalt-rich bimetallic silicide exhibits an equal activity to the reference noble metal catalysts (Au, Pd, and Pt) and a significantly higher activity than transition metal catalysts. Moreover, the bimetallic silicide as an intermetallic compound catalyst has demonstrated robust acid corrosion resistance compared to the corresponding metal catalysts.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2020
·
IF 5.065
Wentao He,Qundi Yu,Nan Wang,Xiao-kun Ouyang
Chitosan (CS)—a natural macromolecule—exhibits various limitations, such as difficult recovery, low mechanical strength, and low adsorption capacity. In this work, to address these shortcomings, polyvinyl alcohol (PVA) was mixed into chitosan beads, thereby improving the mechanical strength and acid resistance of CS. Following this, ethylenediamine tetraacetic acid (EDTA) was introduced to the surface of the mixed beads to fabricate PVA-CS-EDTA, a functionalized adsorbent. Series characterization methods are employed to study the surface morphology, chemical groups, and adsorption strengths of the adsorbents. Moreover, the effects of various adsorption conditions on Cu(II) adsorption are studied. According to the results, the adsorption of Cu(II) by the adsorbent beads follows pseudo-second-order kinetics and the Langmuir adsorption isotherm model. The maximum adsorption capacity of PVA-CS-EDTA is 127.81 mg/g, which is substantially higher than that of the CS beads. In addition, the PVA-CS-EDTA beads remain structurally intact even after treatment with an acidic solution (pH = 2). The higher adsorption capacity and acid resistance of the developed CS are promising for wide applications in the field of adsorption.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Bi-Han Guan,Wu-Tong Yin,Bo-Han Cao,Chen Zhao,Jiang Pan,Jian-He Xu
L-Carnosine (L-Car) is a biologically active dipeptide with antioxidant and anti-aging effects, formed by condensation of β-alanine (β-Ala) with L-histidine (L-His), which is used widely in the pharmaceutical and cosmetic industries. Here we report a dipeptide hydrolase originating from Bacillus megaterium , designated as Bm PepD, whose synthetic activity reached 6.5 times that of Sm PepD, which is the highest active dipeptidase reported so far for L-Car biosynthesis in vitro . By site-directed saturation mutagenesis, we obtained a significantly improved variant (T171N) of Bm PepD. It showed a specific activity of 22.9 U mg −1 protein , reaching 1.4 times that of wild-type Bm PepD or 9.1 times that of Sm PepD, which is the highest ever reported among this enzyme class. After optimizing the reaction conditions of variant Bm PepD T171N , we performed the synthetic reaction of L-Car simply from the two free amino acids (0.2 M L-His and 6.5 M β-Ala), achieving a titer of 31.3 mM L-Car with a specific productivity of 283 g Car · g catalyst −1 . This work provides a highly active and substrate (β-alanine)-tolerant dipeptide hydrolase for the facile synthesis of dipeptide L-Car via reversed hydrolysis.
研究领域:
生物化学
·
酶工程
·
合成生物学
✓ 已验证
DOI
高影响因子
ACS Catalysis
·
2024
·
IF 11.3
Zhao An,Huanqiao Li,Xiaoming Zhang,Zhangxun Xia,Hong Zhang,Wenling Chu,Shansheng Yu,Suli Wang,Gongquan Sun
With much enhanced fuel flexibility to overcome the shortcomings of hydrogen production and storage, high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are still facing challenges of activity loss of oxygen reduction electrocatalyst under the working circumstance of phosphoric acid (PA) electrolyte. Dissolution and leaching of metal component of PtM (M = Cu, Co, Ni···) electrocatalysts is one of the key factors that degrade their initial resistance toward PA and hinder the accessing of activity and durability simultaneously. Here, we report an ultradurable PtRhCu@Pt/C electrocatalyst with a high mass activity of 0.90 A mg–1Pt, which only decreased by 14.4% after 30K ADT cycles in the half-cell and reaches the DOE at 2025 target (<30 mV at 0.8 A cm–2) with 27 mV voltage loss at 0.8 A cm–2 in the single-cell. After adding 0.1 M PA into the electrolyte, the half-wave potential of PtRhCu@Pt/C is negatively shifted by only 52 mV, much lower than that of commercial Pt/C (90 mV). Moreover, the HT-PEMFC assembled by this catalyst delivers a preeminent peak power density of 529 and 977 mW cm–2 under H2–air and H2–O2 conditions, respectively. Experiments and theoretical calculations reveal that the ligand effect arising from the sublayer Cu is attributed to the ability of PA resistance, while the self-healing behavior and the synergy between the PtRhCu core and the Pt shell ensures high stability.
研究领域:
材料科学
·
能源科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMOSPHERE
·
2022
·
IF 8.943
Chen Li,Guoqing Feng,Menghan Sun,Zonglin Pan,Xiaoqing Yan,Xinfei Fan,Chengwen Song,Tonghua Wang
Acidic organic wastewater with toxic and carcinogenic properties has long been a tough problem for industrial treatment. To break down the barrier of poor acidic stability as well as the high cost of materials and reactors, a novel strategy of utilizing a high-performance and acid-tolerant TiO 2 /carbon electrocatalytic membrane (TiO 2 /CEM) for acidic organic wastewater treatment was proposed. Study results showed that high concentrations of organic pollutants were separated and degraded by the synergistic effects of membrane separation and electrocatalytic oxidation simultaneously on the TiO 2 /CEM. The great treatment performance with membrane removal efficiency of >97.4% was obtained by treating acidic rhodamine B (RhB) dye wastewater under optimized applied voltage. Treatment experiments under various pH and electrochemical tests demonstrated the outstanding acid-tolerant property and long service life of TiO 2 /CEM. Furthermore, the feasibility of TiO 2 /CEM for industrial application and various acidic organic wastewater treatment was proved by treating typical organic pollutants (phenol, tetracycline and oil) under high acidic circumstances.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nanoscale
·
2018
·Vol. 10
·期 34
·15932-15937
·
IF 7.233
Feng Wang,Jian Lin,Hongye Wang,Shansheng Yu,Xiaoqiang Cui,Asghar Ali,Tao Wu,Yang Liu
Herein, the ECL behaviors of precise mono-Cu+ ion doped Cd–In–S supertetrahedral chalcogenide nanoclusters (Cu@CdInS NCs) were investigated, and the effect of mono-Cu+ ions at the vacancy site of NCs on ECL emission performance was also elucidated. Precise mono-Cu+ ion doping not only induced new ECL emission at 596 nm with enhanced efficiency as high as 21.72% relative to [Ru(bpy)3]2+, but also improved acid tolerance of the ECL performances of NCs. In addition, a simple, fast and label-free dopamine ECL sensor with excellent selectivity was achieved.
研究领域:
分析化学
·
纳米技术
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）