INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2019
·
IF 4.784
Zhang Yajuan,Duan Yajuan,Zhong Lingli,Li Zhoukun,Cui Zhongli,Huang Yan
The asymmetric reduction of prochiral ketones is a promising process for synthesis of optically active alcohols. The aldo-keto reductase (AKR) is an attractive candidate of biocatalyst, due to its high enantioselectivity and environmentally friendly reaction conditions. In this work, nine putative AKR encoding genes from Corallococcus sp. EGB were cloned and expressed in Escherichia coli . Of these produced enzymes (CoAKRs), CoAKR7 exhibited reductive activity to various ketones and ketoesters, especially very high activity toward ethyl 4-chloro-3-oxobutanoate (COBE) with NADPH as the coenzyme. The CoAKR7 was optimally active at pH 7.0 and 50 °C. The apparent K m and V max for COBE was 14.18 U/mg and 0.269 mM, respectively. Moreover, CoAKR7 catalyzed an anti-Prelog reduction of COBE to ( S )-ethyl-4-chloro-3-hydroxybutanoate (CHBE) with e.e. >99%. Enzyme-substrate-cofactor docking analysis elucidated the molecular mechanism of the substrate stereospecificity, providing basis for protein engineering of these enzymes for applications in the synthesis of valuable chemicals.
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OCEAN ENGINEERING
·
2019
·
IF 2.73
Jiangfan Chang,Xiaoyan He,Xiuqin Bai,Chengqing Yuan
Biofilm formation is crucial for subsequent biofouling. Various factors can affect the biofilm formation. Here we report the influence of hydrodynamic shear force on adhesion morphology and biofilm conformation of Bacillus sp. on stainless steel by a flow cell system. Static, laminar and turbulent conditions were selected for this study. The applicability of this flow cell was evaluated by computational fluid dynamics (CFD). Stable wall shear stresses were successfully obtained. The results showed that the spatial distribution of bacteria changed from single-cell to cluster under the effect of shear force and the higher shear force created smoother and denser clusters. The different morphology of clusters under different flow conditions was mainly due to the increased nutrient supply to the clusters with the increase of flow velocity. Under the effect of shear force, Bacillus sp. could change the shape and increase the production of extracellular polymeric substance which could reduce the effect of shear force and enhance the connection and adhesion, respectively. Under low shear force, biofilm preferred to form irregular and complicated structure which could lead to the formation of tower like biofilm and inhibit the external mass transfer . The results could shed some light on biofilm control strategies.
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INTERNATIONAL BIODETERIORATION & BIODEGRADATION
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2017
·
IF 2.962
Yu Jiang,Tao Deng,Yu Shang,Kai Yang,Hongyu Wang
Phenol-containing industrial wastewater disposal has received much attention in recent years due to its toxicity and slow biodegradation. In this work, the isolated fungal strain Debaryomyces sp. was entrapped into Ca-alginate beads with nanoscale Fe 3 O 4 to improve phenol biodegradation ability. Freely suspended cells as well as Ca-alginate immobilized cells without nanoscale particles were also prepared. Phenol removal by free cells and two kinds of Ca-alginate beads was evaluated with different initial phenol concentrations, temperatures, and salinities . The phenol biodegradation kinetics and optimal dosage of nano-Fe 3 O 4 during the preparation of Ca-alginate beads were also determined. The results showed that immobilized Debaryomyces strain had better biodegradation performance than free cells under harsh conditions. Phenol removal rates were highest when using magnetically immobilized cells, followed by nonmagnetically cells. More than 99.9% of phenol was degraded within 80 h by immobilized cells with nano-Fe 3 O 4 when initial phenol concentration was over 900 mg L −1 while the phenol removal efficiencies of free cell and immobilized cells without nano-Fe 3 O 4 were 34.5% and 81.3%, respectively during the same periods of time. The reusability tests were carried out and the results indicated good stability of immobilized cells in saline environments, which was practical in actual industrial wastewater treatment .
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2013
·Vol. 21
·期 6
·4366-4375
·
IF 2.618
Zhang Jianying,Ni Yanyan,Ding Tengda,Zhang Chunlong
Dissolved organic matter (DOM) affects arsenite [As(III)] toxicity by altering its sorption equilibrium at the cell wall interface. A better understanding of such mechanism is of great importance to assess As(III) ecotoxicity in aquatic systems. Batch experiments were conducted to study the effects of DOM on the regulation of As(III) sorption and toxicity in the diatom Navicula sp. The influence of humic acid (HA) on As(III) toxicity was assessed by measuring algal growth, chlorophyll a , and reactive oxygen species (ROS), whereas As(III) mobility across the cell wall was estimated by determining the concentration of intracellular, cell-wall-bound, and free As(III) ions in cell media. Results showed that the effects of HA on arsenite toxicity varied depending on various combinations of As(III)-HA concentrations. EC 50 had an approximate threefold increase from 8.32 (HA-free control) to 22.39 μM (at 20 mg L −1 HA) when Navicula sp. was exposed to 1.0–100.0 μM of As(III), compared to an overall low complexation ratio of HA-As(III) in a range of 0.91–6.00 %. The cell wall-bound and intracellular arsenic content decreased by 19.8 and 20.3 %, respectively, despite the lower arsenite complexation (2.10 ± 0.16 % of the total As). Meanwhile, intracellular ROS was decreased by 12.6 % in response to 10.0 μM As(III) and 10 mg L −1 HA vs. the HA-free control. The significant contrast indicated that complexation alone could not explain the HA-induced reduction in arsenite toxicity and other factors including HA–cell surface interactions may come into play. Isotherms describing adsorption of HA to the Navicula sp. cells combined with morphological data by scanning electron microscopy revealed a protective HA floccule coating on the cell walls. Additional Fourier transform infrared spectroscopic data suggested the involvement of carboxylic groups during the adsorption of both HA and As(III) on the Navicula sp. cell surface. Collective data from this study suggest that cell wall-bound HA can moderate As(III) toxicity through the formation of a protective floccule coating occupying As(III) sorption sites and decreased effective functional groups capable of binding As(III). Our findings imply that As(III) toxicity can be alleviated due to the increased hindrance to cellular internalization of As(III) in the presence of naturally abundant DOM in water.
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CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2015
·Vol. 31
·期 4
·645-650
·
IF 0.875
Geng Zhi,Zhu Suiyi,Yu Yang,Lu Ying,Lin Rao,Guo Shujun,Bian Dejun,Yang Xia,Huo Mingxin,Huo Hongliang
Novel matrix beads for the immobilization of strain Comamonas testosteroni sp. bdq06 to degrade quinoline were fabricated from polyethersulfone(PES). The beads have an average size of 3 mm and a surface dense layer of 20 microns. To help adhesion and proliferation of bacterial cells, the surfaces of the PES beads were etched, and numerous holes about 1.5 micrometers in diameter were generated as tunnels for cell colonizing in the larger internal cavities of about 5 micrometers in diameter. The quinoline degradation was remarkably enhanced by the cells immobilized in PES beads compared with that by the free cells at pH 5.0 or 10.0 and a temperature of 40 °C. The enhanced degradation of quinoline was contributed to the biofilm on the surface of PES beads, resulting in the significant reduction of retention time from 9 h to 2 h. Furthermore, the beads remain intact after the ultrasonic treatment of them for 30 min or recycling 50 times, indicating that they have excellent mechanical strength, flexibility and swelling capacity. Thus, PES beads have great potential to be matrix for the cell immobilization in bioaugmentation.
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APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2014
·Vol. 174
·期 4
·1572-1580
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IF 1.687
Gao Xiaoxin,Ma Zhengfei,Yang Limin,Ma Jiangquan
Burkholderia sp. EG13 with high ethylene glycol-oxidizing activity was isolated from soil, which could be used for the synthesis of glycolic acid from the oxidation of ethylene glycol. Using the resting cells of Burkholderia sp. EG13 as biocatalysts, the optimum reaction temperature and pH were 30 °C and 6.0, respectively. After 24 h of biotransformation, the yield of glycolic acid from 200 mM ethylene glycol was 98.8 %. Furthermore, an integrated bioprocess for the production of glycolic acid which involved in situ product removal (ISPR) was investigated. Using fed-batch method with ISPR, a total of 793 mM glycolic acid has been accumulated in the reaction mixture after the 4th feed.
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Nature Communications
·
2024
·Vol. 15
·期 1
·1-15
·
IF 14.7
Tang Si,Cheng Xueyu,Liu Yaqing,Liu Lu,Liu Dai,Yan Qi,Zhu Jianming,Zhou Jin,Jiang Yuyang,Hammerschmidt Katrin,Cai Zhonghua
Diazotrophic cyanobacteria can fix nitrogen gas (N 2 ) but are usually scarce in nitrogen-limited coastal waters, which poses an apparent ecological paradox. One hypothesis is that high salinities (> 10 g/L NaCl) may inhibit cyanobacterial N 2 fixation. However, here we show that N 2 fixation in a unicellular coastal cyanobacterium exclusively depends on sodium ions and is inhibited at low NaCl concentrations (< 4 g/L). In the absence of Na + , cells of Cyanothece sp. ATCC 51142 (recently reclassified as Crocosphaera subtropica ) upregulate the expression of nifHDK genes and synthesise a higher amount of nitrogenase, but do not fix N 2 and do not grow. We find that the loss of N 2 -fixing ability in the absence of Na + is due to insufficient ATP supply. Additional experiments suggest that N 2 fixation in this organism is driven by sodium energetics and mixed-acid fermentation, rather than proton energetics and aerobic respiration, even though cells were cultured aerobically. Further work is needed to clarify the underlying mechanisms and whether our findings are relevant to other coastal cyanobacteria.
研究领域:
微生物学
·
海洋生物学
·
生物化学
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Polymers
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2024
·Vol. 16
·期 5
·692
·
IF 4.7
Yi Mao,Yajuan Sun,Cheng Yang
A dual biofunctional hydrogel (HQCS-SP) wound dressing, offering antibacterial properties and a biological response, was innovatively designed and developed to repair full-layer skin defects. The HQCS-SP hydrogel creates an artificial matrix that facilitates cell recruitment, extracellular matrix deposition, exhibiting exceptional tissue affinity, robust self-healing, effective hemostatic capabilities and accelerates wound healing. It is synthesized by crosslinking modified chitosan (HQCS) with spirulina protein (SP) and Fe3+. The HQCS provides antibacterial, antioxidant, good tissue affinity and excellent hemostasis performance. The incorporation of SP not only reinforces the antioxidant, antibacterial, anti-inflammatory, and pro-angiogenesis effects but also participates in the regulation of signal pathways and promotes wound healing. Therefore, this study offers a new visual angle for the design of advanced functional trauma dressings with great application potential in the bio-medical field.
研究领域:
生物医学工程
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材料科学
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伤口愈合
·
组织工程
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AQUATIC TOXICOLOGY
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2022
·
IF 5.202
Chun Wang,Lijuan Jiang,Wenxi Huang,Changhai Wang,Meilin He
The vertical movement of large-size and high-density MPs in the water column is usually along with dynamic changes in light intensity. However, whether the change in light availability affects the bioeffects of MPs on surrounding microalgae is currently unknown. This study investigated the effects of micron-sized polyvinyl chloride (mPVC, 143.5 μm) microplastics, alone and in combination with light intensity (from 7.5 to 162.5 μmol·m −2 ·s −1 ) on the growth and physiology of Desmodesmus sp. Although mPVC did not impact microalgal growth under optimal light (40 and 93.8 μmol·m −2 ·s −1 ), it could induce a no-contact shading effect, thereby significantly affecting the physiology of Desmodesmus sp. The growth of Desmodesmus sp. exposed to mPVC was enhanced under a high light intensity of 162.5 μmol·m −2 ·s −1 which can induce growth inhibition but was retarded when under a light inadequacy condition (20 μmol·m −2 ·s −1 ), along with a dose-dependent effect. Significantly, the photosynthesis of Desmodesmus sp. was a highly sensitive metabolic pathway to mPVC stress and largely influenced by the plastic particles under different light conditions. Additionally, mPVC modulated the energy metabolism strategy of Desmodesmus sp., depending on exposure dose and external light availability. Our findings provided a critical basis for the risk assessment of MPs in fluctuating light conditions.
研究领域:
环境科学
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微生物学
·
生态毒理学
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LWT-FOOD SCIENCE AND TECHNOLOGY
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2022
·
IF 6.056
Ruiguo Cui,Xinyi Che,Lilang Li,Dongxiao Sun-Waterhouse,Jia Wang,Yonghua Wang
Lipase MAJ1 from Janibacter sp. is an sn-1,3 specific lipase for preparing long-medium-long (LML) type structured triacylglycerols (TAGs), but low optimum reaction temperature limited its application. Based on the structure built with Alphafold2 and MD simulation, we performed mutagenesis on the lid domain. The mutants L171A, A182P and P192C-T100C increased the optimum temperatures by 5 °C, 5 °C and 10 °C, respectively. The combination of three mutations (MAJ1 M4) increased the optimum temperature by 10 °C and a 5.5-fold increase in activity on tricaprylin. The residual activity of MAJ1 M4 was 70% after 60 min incubation at 45 °C, compared to no residual activity determined for MAJ1 wild-type in the same condition. The production of LML with the immobilized lipase MAJ1 M4-catalyzed interesterification was 57.1 mol% in 24 h compared with 44.3 mol% produced by MAJ1 wild-type. Moreover, the immobilized MAJ1 M4 retained 93% productivity after 13 cycles of synthesis. This mutagenesis design would pave the way for the application of MAJ1 in the food industry.
研究领域:
生物化学
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食品科学
·
分子生物学
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MOLECULES
·
2016
·Vol. 21
·期 8
·970
·
IF 2.465
Ying Han,Erli Tian,Dongbo Xu,Min Ma,Zixin Deng,Kui Hong
During our search for interesting bioactive secondary metabolites from mangrove actinomycetes, the strainStreptomycessp. 219807 which produced a high elaiophylin yield of 4486 mg/L was obtained. A new elaiophylin derivative, halichoblelide D (1), along with seven known analogues2–8was isolated and identified from the culture broth. Their chemical structures were determined by detailed analysis of 1D and 2D NMR and HRMS data. The absolute configuration of halichoblelide D (1) was confirmed by comparing the CD spectrum with those of the reported analogues. Compounds1–7exhibited potent cytotoxic activities against HeLa and MCF-7 cells with IC50values ranging from 0.19 to 2.12 μM.Keywords:mangrove actinomycetes;Streptomycessp. 219807;elaiophylin;cytotoxic
研究领域:
微生物学
·
药物化学
·
肿瘤学
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AICHE JOURNAL
·
2026
·
IF 4.4
Pei Qiao,Yi Guo,Yanan Liu,Chenghua Zhu,Di Cheng,Youshan Zhou,Panpan Song
Phthalate esters (PAEs) are pervasive environmental pollutants that require efficient biodegradation. The substrate specificity of PAEs-degrading microorganisms hinges critically on the catalytic selectivity of microbial esterases. To elucidate the molecular basis of the specificity of Type III PAEs esterases, we developed a chromogenic assay and further integrated machine learning-driven enzyme mining with functional characterization and molecular dynamics analysis. A novel microorganism, Acinetobacter sp. DY-1, was isolated with diverse PAEs-degrading capacities. The esterase 1952 from strain DY-1 exhibited broad substrate specificity and high catalytic efficiency, with a marked preference for long-chain PAEs, such as DEHP. Molecular dynamics simulations revealed stable hydrophobic interactions underpinning 1952s affinity for DEHP. Through targeted mutagenesis, we identified key residues (Leu64, Leu68, and His229) that are essential for substrate binding and catalysis. Their substitution with polar residues drastically reduced DEHP degradation, while the G178Y mutant enhanced activity via π-stacking interactions. This study deciphers the structural determinants of PAE esterase specificity, enabling precise enzyme engineering.
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