JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2020
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IF 4.192
Xiaofeng Zhang,Xinqi Xu,Xuemei Yao,Rong Wang,Hengtao Tang,Xin Ju,Liangzhi Li
Ribose-5-phosphate isomerase B is of great importance for biocatalysis and biosynthesis, but the multifunctional residues in active sites hinder the research efforts. This study employed rational design strategies to locate the key residues of RpiB from Ochrobactrum sp. CSL1 (OsRpiB). A single-mutant S9T of a noncontact residue showed 80% activity improvement toward d-allose. A double-mutant S98H/S134H further increased the activity to 3.6-fold. The mutations were analyzed by kinetics and molecular dynamics analyses, indicating that S9T might enhance the substrate binding and catalysis by inducing a steric effect, and S98H/S134H could strengthen both ring opening and binding of d-allose. Though S98H/S134H showed low temperature stability, its potential was explored by isomerizing d-allose to d-psicose with higher conversion and in less reaction time. The findings of this study were beneficial for illustrating the complex functions of key residues in RpiBs and applying OsRpiB in preparing rare sugars.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
·
IF 5.589
Shanshan Sun,Haizhen Wang,Binxin Fu,Hao Zhang,Jun Lou,Laosheng Wu,Jianming Xu
Rhodococcus sp. WB9, a strain isolated from polycyclic aromatic hydrocarbons contaminated soil, degraded phenanthrene (PHE, 100 mg L −1 ) completely within 4 days. 18 metabolites were identified during PHE degradation, including 5 different hydroxyphenanthrene compounds resulted from multiple routes of initial monooxygenase attack. Initial dioxygenation dominantly occurred on 3,4-C positions, followed by meta -cleavage to form 1-hydroxy-2-naphthoic acid (1H2N). More than 95.2% of 1H2N was transported to and kept in extracellular solution without further degradation. However, intracellular 1H2N was converted to 1,2-naphthalenediol that was branched to produce salicylate and phthalate. Furthermore, 131 genes in strain WB9 genome were related to aromatic hydrocarbons catabolism, including the gene coding for salicylate 1-monooxygenase that catalyzed the oxidation of 1H2N to 1,2-naphthalenediol, and complete gene sets for the transformation of salicylate and phthalate toward tricarboxylic acid (TCA) cycle. Metabolic and genomic analyses reveal that strain WB9 has the ability to metabolize intracellular 1H2N to TCA cycle intermediates, but the extracellular 1H2N can’t enter the cells, restricting 1H2N bioavailability and PHE mineralization.
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ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
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2019
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IF 4.527
Zeyu Wang,Cong Chen,Huan Liu,Dzmitry Hrynshpan,Tatsiana Savitskaya,Jianmeng Chen,Jun Chen
Multi-walled carbon nanotubes (MWCNTs) promote biodegradation in water treatment , but the effect of MWCNT on denitrification under aerobic conditions is still unclear. This investigation focused on the denitrification performance of MWCNT and its toxic effects on Alcaligenes sp. TB which showed that 30 mg/L MWCNTs increased NO 3 - removal efficiency from 84% to 100% and decreased the NO 2 - and N 2 O accumulation rates by 36% and 17.5%, respectively. Nitrite reductase and nitrous oxide reductase activities were further increased by 19.5% and 7.5%, respectively. The mechanism demonstrated that electron generation (NADH yield) and electron transportation system activity increased by 14.5% and 104%, respectively. Cell membrane analysis found that MWCNT caused an increase in polyunsaturated fatty acids, which had positive effects on electron transportation and membrane fluidity at a low concentration of 96 mg/kg but caused membrane lipid peroxidation and impaired membrane integrity at a high concentration of 115 mg/L. These findings confirmed that MWCNT affects the activity of Alcaligenes sp. TB and consequently enhances denitrification performance.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2018
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IF 2.829
Leila Abdoli,Chunhai Guo,Xiuyong Chen,Xiaoyan He,Hua Li
Formation of microbial biofilm on marine structures is crucial for subsequent attachment of macro fouling species and understanding the impact of fluid conditions on formation and growth of the biofilm is essential for preventing biofouling. Here we report the effect of shear stresses generated by laminar and weakly turbulent flow on the adhesion of typical marine bacterium Bacillus sp. biofilm on stainless steel . Numerical simulation was carried out to calculate the distribution of pressure and shear stress applied on adhered bacteria. The shear stress was proportional to both the distance from the center of rotating disk and rotation speed. The stress reached 18 Pa as the flow velocity was 2.4 m/s and the rotation speed was 600 rpm. Further adhesion testing revealed that development of the bacterial biofilm in early stage was unaffected by the shear stresses. However, shear stress regulated the adherence orientations of the bacteria on the steel surface. Turbulent flow obviously shaped development of the architecture of the biofilm, as revealed by CLSM and SEM characterization. Biofilm growth patterns were clearly observed under weakly turbulent flow, however, they were not seen under laminar flow . The microcolonies assumed elongated forms, possibly triggered by exerted pressure drag force. The results give insights into possibly controlling the formation of marine biofilm on marine infrastructures for desired antifouling performances.
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INDUSTRIAL CROPS AND PRODUCTS
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2018
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IF 3.849
Pei Wang,Zhaodi Ke,Juanjuan Yi,Xin Liu,Limin Hao,Qiaozhen Kang,Jike Lu
To enhance the stability of lipases, the additive method is attractive because of its high efficiency and simplicity, of which β-cyclodextrin (β-CD), as an additive has attracted attention. In the present study, the effects of β-CD on enzymatic hydrolysis of hemp seed oil by lipases were investigated. The stability, spectroscopy, and reusability of C andida sp.99–125 were compared by the addition of β-CD, respectively. The results showed that Candida sp.99–125 could produce the highest yield of α-linolenic acid (ALA, 18.27%, w/w) in the presence of β-CD after 24h, and the thermal stability of lipase was also improved. The UV spectroscopy showed that the absorbance of lipase decreased with increasing concentrations of β-CD and the fluorescence result was similar. Moreover, the reusability of lipase with β-CD was better than free lipase. This study revealed that β-CD could increase hydrolysis activity and stability of the lipase, thereby improving the hydrolytic process of hemp seed oil by Candida sp.99–125.
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RSC Advances
·
2014
·Vol. 4
·期 86
·45920-45929
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IF 3.708
Lisha Tan,Jiang Xu,Xiaoqin Xue,Zimo Lou,Jin Zhu,Shams Ali Baig,Xinhua Xu
Silica-coated magnetite (Fe3O4@SiO2) nanoparticles functionalized with amino, imino and sulfonic groups (Fe3O4@SiO2–mPD/SP) were successfully synthesized via a facile chemical oxidative polymerization of m-phenylenediamine (mPD) and m-sulfophenylenediamine-4-sulfonic acid (SP) monomers, and utilized for selective removal of Pb(II) and Cr(VI) from aqueous solutions. It was revealed by the characterizations that the polymers formed on Fe3O4@SiO2 nanoparticles were the true copolymers with a mPD–SP unit, rather than a mixture of mPD and SP homopolymers. Fe3O4@SiO2–mPD/SP nanocomposites could be easily separated from aqueous solutions within 30 s. The maximum adsorption capacities of Pb(II) (83.23 mg g−1) and Cr(VI) (119.06 mg g−1) on Fe3O4@SiO2–mPD/SP nanocomposites were obtained at the mPD/SP molar ratios of 95 : 5 and 50 : 50, respectively. Moreover, satisfactory selective removal of Pb(II) and Cr(VI) from their mixtures with Cu(II) and Ni(II) ions were exhibited by the Fe3O4@SiO2–mPD/SP (95 : 5) and Fe3O4@SiO2–mPD/SP (50 : 50), respectively. The Pb(II) adsorption equilibrium was reached within 5 min by Fe3O4@SiO2–mPD/SP (95 : 5). The adsorption data of Pb(II) and Cr(VI) were both fitted well to the Freundlich isotherm and followed the pseudo-second-order kinetic model. The adsorption mechanism of Pb(II) and Cr(VI) on Fe3O4@SiO2–mPD/SP nanocomposites included five processes, namely: ion-exchange, complexation adsorption, reduction reaction, electrostatic attraction and physical adsorption. The enhanced adsorption performance of nanoparticle-based magnetic adsorbents for selective removal of heavy metal ions can be achieved with such a copolymerization strategy.
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APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2015
·Vol. 178
·期 3
·558-575
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IF 1.735
Liang Jiayuan,Zhang Yun,Sun Aijun,Deng Dun,Hu Yunfeng
A novel microbial esterase BSE01281 identified from the Indian Ocean was cloned, expressed, and functionally characterized. Esterase BSE01281 could enanoselectively resolve (±)-1-phenylethanol and (±)-1-phenylethyl acetate through two types of enzymatic reactions. After the optimization of enzymatic reactions, BSE01281 could efficiently generate ( R )-1-phenylethyl acetate with high enantiomeric excess (>99 %) and high conversion (42 %) after 96 h trans-esterification reactions. Additionally, BSE01281 could also produce ( R )-1-phenylethanol ( e.e . > 99 %) and ( S )-1-phenylethyl acetate ( e.e . > 95 %) at a conversion of 49 % through direct hydrolysis of inexpensive racemic 1-phenylethyl acetate for 8 h. Optically pure ( R )-1-phenylethanol generated from direct enzymatic hydrolysis of racemic 1-phenylethyl acetate by BSE01281 is not easily prepared by dehydrogenases, which generally follow the “Prelog’s rule” and give ( S )-1-phenylethanol instead.
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INTERNATIONAL BIODETERIORATION & BIODEGRADATION
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2015
·
IF 2.131
Lin-Na Du,Gang Li,Yu-Hua Zhao,He-Kun Xu,Yang Wang,Ying Zhou,Liang Wang
We investigated biodegradation of the azo dye methyl orange (MO) by Aeromonas sp. DH-6. Nearly 100% decolorization of MO (100 mg l −1 ) by the strain was observed at pH 3.0–7.0 and a broad temperature range (5–45 °C) after incubation for 12 h. Most of the tested carbon and nitrogen sources could significantly enhance MO decolorization, but of the metal ions , only Mg 2+ , Mn 2+ , and 1.5 mM of Ca 2+ could increase the decolorization. The strain still showed a high capacity for decolorizing MO even at a concentration of up to 1000 mg l −1 . Based on the gas chromatography-mass spectrometry analysis (GC-MS) and high performance liquid chromatography analysis (HPLC) data, N,N-dimethyl- p -phenylenediamine and 4-aminobenzenesulfonic acid were identified as the main intermediates of MO biodegradation, and a possible degradation pathway was proposed. Moreover, results of enzyme analysis indicated that laccase, NADH-DCIP reductase, and azo reductase were responsible for the degradation. Overall, high biodegradation efficiency at a broad range of temperatures and dye concentrations suggested that strain DH-6 would have high potential in the bioremediation of azo dyes.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Xiong Li,Chuyi Li,Wanzi Yao,Jian Mao
Carrageenan oligosaccharides have attracted significant attention due to their excellent biological activities, and they can be produced by carrageenases. In this study, a novel marine bacterium, Shewanella sp. LE8, was used to enzymatically degrade carrageenan, and the κ-, ι-, and λ-carrageenases produced by the bacterium were characterized. The crude enzyme derived from media exhibited κ-carrageenase activity, indicating its natural secretion during growth and proliferation. According to the results of molecular weight distribution from HPGPC, λ-carrageenan could be degraded by Shewanella sp. LE8 cells in both 20 mM Tris-HCl buffer and PBS, while ι-carrageenan can only be hydrolyzed in PBS environment, indicating the activation of ι-carrageenase in Shewanella sp. LE8 was dependent on the presence of Na + ions. The components of carrageenan hydrolysates were determined by ESIMS, and results revealed that κ-carrageenan hydrolysates were primarily consisted of G4S-DA, [G4S-DA] 2 and [G4S-DA] 3 , while ι-carrageenan hydrolysates were predominantly composed of [G4S-DA2S] 2 . Moreover, the fragment ions of λ-carrageenan revealed that the hydrolytic process not only encompasses enzymatic cleavage of glycosidic bonds but also involves the participation of sulfatase. The precise structure was further elucidated through NMR analysis, confirming that the end-products of ι-carrageenase were neoι-carratetraose. The results highlight the potential of Shewanella sp. LE8 for industrial applications in the production of ι-carrageenan oligosaccharides.
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Algal Research-Biomass Biofuels and Bioproducts
·
2025
·
IF 4.5
Juan Liu,Shiqing Sun,Kangyu Chen,Shumei Gao,Dixing Chen,Yuejin Zhang,Changwei Hu
Fungi-microalgae consortia have great potential in microalgae harvesting and wastewater treatment. However, the symbiotic mechanisms underlying diffusible signaling metabolite production by fungi and microalgae remain unclear. Here, the positive impacts of Clonostachys rosea on Chlorella sp. were investigated using metabolomics and transcriptomics during a 5-day non-contact co-culture experiment. Co-cultured Chlorella sp. had a significantly higher growth rate and better photosynthetic performance than its mono-culture equivalent. The metabolites played important roles in the up-regulation of energy and amino acid metabolism processes in algal cells, whilst transcriptomics showed the up-regulation of genes involved in photosynthesis and signaling molecules. The biosynthesis of tryptophan and indole-3-acetic acid (IAA) was up-regulated in both algal cells and fungi, indicating that IAA is an important diffusible signaling molecule for algal growth regulation. This work provides novel insights into the signaling molecule interactions between fungi and microalgae in fungi-microalgae consortia.
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INTERNATIONAL MICROBIOLOGY
·
2024
·
IF 2.3
Pan Lixu,Yuan Bo,Li Qingqing,Ouyang Ji,Yang Jie,Zhou Yan,Cui Changzheng
Chlorobenzene (CB), extensively used in industrial processes, has emerged as a significant contaminant in soil and groundwater. The eco-friendly and cost-effective microbial remediation has been increasingly favored to address this environmental challenge. In this study, a degrading bacterium was isolated from CB-contaminated soil at a pesticide plant, identified as Pandoraea sp. XJJ-1 (CCTCC M 2021057). This strain completely degraded 100 mg·L −1 CB and showed extensive degradability across a range of pH (5.0–9.0), temperature (10–37 °C), and CB concentrations (100–600 mg·L −1 ). Notably, the degradation efficiency was 85.2% at 15 °C, and the strain could also degrade six other aromatic hydrocarbons, including benzene, toluene, ethylbenzene, and xylene ( o- , m- , p- ). The metabolic pathway of CB was inferred using ultraperformance liquid chromatography, gas chromatography-mass spectrometry, and genomic analysis. In strain XJJ-1, CB was metabolized to o -chlorophenol and 3-chloroxychol by CB monooxygenase, followed by ortho- cleavage by the action of 3-chlorocatechol 1,2-dioxygenase. Moreover, the presence of the chlorobenzene monooxygenation pathway metabolism in strain XJJ-1 is reported for the first time in Pandoraea . As a bacterium with low-temperature resistance and composite pollutant degradation capacity, strain XJJ-1 has the potential application prospects in the in-situ bioremediation of CB-contaminated sites.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2024
·
IF 5.7
Zheyi Zhang,Sainan Yu,Jiawei Gu,Feilong Tan,Sibao Wan,Haiyan Gao,Zhen Qin
β-1,3-Glucanases have prospective applications in areas such as functional oligosaccharide preparation, plant protection, and breweries. In this study, a glycoside hydrolase (GH) family 17 β-1,3-glucanase (BbGlc17A) from Bacteroidetes bacterium from a microbial mat metagenome from the Great Salt Lake was identified. BbGlc17A catalyzed the hydrolytic conversion of laminarin into β-glucooligosaccharides with polymerization degrees of 3–8. The optimal catalytic conditions of BbGlc17A were pH 6.5 and 30 °C. In addition to its hydrolytic activity, BbGlc17A also exhibited transglycosidase activities, involving catalysis of the formation of new β-1,6-glycosidic bonds. BbGlc17A exhibits the classic (β/α)8 TIM-barrel structure and possesses an elongated catalytic groove, distinguishing it from other typical β-1,3-glucanases, which promote the forward direction of the transglycoside reaction. This effectively highlights the potential of the enzyme to convert β-1,3-glucan into mixed functional oligosaccharides. These results reveal the catalytic properties and the application potential of the GH family 17 β-1,3-glucanase and provide valuable information about the group of carbohydrate-active enzymes in biochemistry.
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