SCIENCE OF THE TOTAL ENVIRONMENT
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2019
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IF 5.589
Yangyang Wang,Wenhao Zhan,Qiang Ren,Shanshan Cheng,Junnan Wang,Xiaoyu Ma,Chaosheng Zhang,Yansong Wang
A bacterial strain ( Gordonia sp. Lff) capable of efficiently degrading di-(2-ethylhexyl) phthalate (DEHP) was isolated from river sludge. The optimal pH and temperature for the degradation of DEHP by Lff were 7.0 and 35 °C, respectively. Lff could degrade high concentrations of DEHP (100–2000 mg/L) with a degradation efficiency of over 91.43%. The DEHP degradation curves fit well with first-order kinetics, with a half-life ranging from 0.598 to 0.746 d. Substrate inhibition analyses showed that the maximum specific degradation rate, half-saturation constant and inhibition constant were 0.8 d −1 , 45.8 mg/L and 462.18 mg/L, respectively. A detailed biodegradation pathway of DEHP was proposed based on GC–MS analysis. Furthermore, Lff could also efficiently degrade DEHP in soils. DEHP or DEHP plus Lff changed the bacterial community in soils, and Lff accelerated the shaping of the bacterial community. To the best of our knowledge, this study is the first to perform a detailed investigation into the biodegradation of DEHP in soil by Gordonia sp. and its effect on the soil bacterial community. These results suggest that Lff is an ideal candidate for the bioremediation of DEHP-contaminated environments.
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APPLIED CLAY SCIENCE
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2018
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IF 3.641
Bo Ruan,Pingxiao Wu,Xiaolin Lai,Huimin Wang,Liping Li,Liya Chen,Chunxi Kang,Nengwu Zhu,Zhi Dang,Guining Lu
The objective of this study was to investigate the interaction between stearic acid-modified montmorillonite (SA-Mt) and Sphingomonas sp. GY2B and its effect on the physical and chemical properties of montmorillonite in the 2 days' biodegradation of phenanthrene . Due to bacterial activities , surface and colloidal properties of the bacteria-treated sample evidently changed in comparison with the untreated SA-Mt. Changes in surface morphology and the agglomerate state of SA-Mt were clearly observed by scanning electron microscopy (SEM) after interaction with GY2B for 2 days. Although the interlayer space of SA-Mt structure remained basically unchanged, the decrease of the structural order and the appearance and shift of several absorbance bands in the Fourier transform infrared (FTIR) spectra verified the structural changes of SA-Mt after bacterial treatment . Besides, the second derivative infrared spectra indicated that bacterial growth and metabolism largely affected the microstructure in SA-Mt. Dissolution rates of major elements were obtained by inductively coupled plasma optical emission spectroscopy (ICP-OES) in the solution, which revealed that bacterial activities enhanced the release of major elements and brought about a significant higher dissolution of Si preferentially from the tetrahedral sheet edges of SA-Mt than Al. The improvement of elemental dissolution in the biotic experiment was attributed to the combined action of pH effect and ligand-promoted process. These results substantiated that microorganisms have a considerable influence on the physicochemical properties and structure in the clay-modulated biodegradation of organic compounds. This study has profound impacts on the clay-modulated biodegradation of hydrophobic organic contaminants in the environment.
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JOURNAL OF HAZARDOUS MATERIALS
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2022
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IF 14.224
Xingxing Peng,Qihang Zheng,Lei Liu,Yuzhe He,Tianyu Li,Xiaoshan Jia
T2, a gram-positive bacterium capable of rapidly degrading tetrabromobisphenol A (TBBPA), and affiliated with the genus Enterobacter , was isolated for the first time from sludge that had been contaminated for several years. The TBBPA degradation data fitted the first-order model well. Under optimal conditions (pH of 7, temperature of 31 °C, TBBPA concentration of 5 mg L −1 , and inoculum size of 5%), 99.4% of the initially added TBBPA was degraded after 48 h. TBBPA degradation fitted the first-order model with the half-life of 3.3 h. These results illustrated that the TBBPA degradation capability of strain T2 was significantly better than that of previously reported bacteria. A total of 17 intermediates were detected, among which five were reported for the first time. Whole-genome sequencing revealed that strain T2 had a chromosome with the total length of 4 854 376 bp and a plasmid with the total length of 21 444 bp. It harbored essential genes responsible for debromination, such as cyp450 , gstB , gstA , and HADH, and genes responsible for subsequent complete mineralization , such as bioC , yrrM , Tam , and Ubil . A key protein of haloacid dehalogenases responsible for the biodegradation of TBBPA may also be involved in the regulation of TBBPA degradation in natural environment. In soil bioremediation experiments, strain T2 showed excellent environmental adaptation. It was able to biodegrade TBBPA and its typical intermediate bisphenol A efficiently. Therefore, it could potentially be applied to treat TBBPA-contaminated sites.
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Microbiology Spectrum
·
2022
·
IF 9.043
Wenzhi Bao,Xing Li,Jinfeng Liu,Rong Zheng,Lijuan Liu,Haibo Zhang
Phenylpyruvate decarboxylase (PPDC) is a crucial enzyme that plays important roles in 2-phenylethanol (2-PE) biosynthesis. In our previous study, we screened a highly efficient PPDC KDC4427 from the novel 2-PE-producing strain Enterobacter sp. CGMCC 5087. Meanwhile, its decarboxylation activity of indolylpyruvate (IPyA) was also higher than other indolylpyruvate decarboxylases (IPDCs) reported so far. In this study, KDC4427 protein was purified and characterized, and its catalytic mechanisms were analyzed by biological methods. The optimum pH and temperature of KDC4427 was pH 6.5 and 35°C, respectively. The enzyme activity was relatively stable between pH 6 and 8 and over the range of temperatures from 25°C to 45°C. KDC4427 showed the highest catalytic efficiency on phenylpyruvic acid (PPA); meanwhile, it also showed high activity for IPyA and 2-ketobutanoic acid, and it was found that KDC4427 belongs to IPDCs by phylogenetic tree analysis. The coverage of the three-dimensional structure of KDC4427 and EcIPDC from Enterobacter cloacae was 96%. Leucine 542, one of the residues in the substrate-binding pocket, is replaced by isoleucine in KDC4427 compared with EcIPDC. Site-directed mutagenesis showed that the transition from leucine to isoleucine was unlikely to make KDC4427 have high catalytic activity for PPA and IPyA; the mutants at glutamate 468 almost completely lost catalytic activities for both PPA and IPyA, indicating that this glutamate was essential for the catalytic activity. Additionally, alanine 387 plays an important role in the substrate selectivity of KDC4427.IMPORTANCE Compared with the chemical synthesis of 2-phenylethanol (2-PE) by condensation of ethylene oxide and benzene, the biological synthesis of 2-PE is a potential method to replace the traditional process. This makes biotransformation gradually become the main way to produce high-quality 2-PE. Phenylpyruvate decarboxylase (PPDC) is the critical enzyme in 2-PE biosynthesis, and it is a momentous point of penetration to increase the production of 2-PE. In this regard, KDC4427 can catalyze phenylpyruvic acid (PPA) to phenylacetaldehyde more efficiently than any other PPDC previously reported. Moreover, it has high activity of indolepyruvate decarboxylases (IPDCs), which will be a great breakthrough in the synthesis of indole-3-acetic acid (IAA). With this study, we offer insights into the KDC4427 catalytic mechanism and significantly expand the toolbox of available α-ketoacid decarboxylases for application in biosynthesis.
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Frontiers in Microbiology
·
2021
·
IF 5.64
Zhao Shuxue,Chen Xi,Sun Qianshu,Wang Fei,Hu Chunhui,Guo Lizhong,Bai Jie,Yu Hao
Indole-3-acetic acid (IAA), known as a common plant hormone, is one of the most distributed indole derivatives in the environment, but the degradation mechanism and cellular response network to IAA degradation are still not very clear. The objective of this study was to elucidate the molecular mechanisms of IAA degradation at the protein level by a newly isolated strain Pseudomonas sp. LY1. Label-free quantitative proteomic analysis of strain LY1 cultivated with IAA or citrate/NH4Cl was applied. A total of 2,604 proteins were identified, and 227 proteins have differential abundances in the presence of IAA, including 97 highly abundant proteins and 130 less abundant proteins. Based on the proteomic analysis an IAA degrading (iad) gene cluster in strain LY1 containing IAA transformation genes (organized as iadHABICDEFG), genes of the β-ketoadipate pathway for catechol and protocatechuate degradation (catBCA and pcaABCDEF) were identified. The iadA, iadB, and iadE-disrupted mutants lost the ability to grow on IAA, which confirmed the role of the iad cluster in IAA degradation. Degradation intermediates were analyzed by HPLC, LC-MS, and GC-MS analysis. Proteomic analysis and identified products suggested that multiple degradation pathways existed in strain LY1. IAA was initially transformed to dioxindole-3-acetic acid, which was further transformed to isatin. Isatin was then transformed to isatinic acid or catechol. An in-depth data analysis suggested oxidative stress in strain LY1 during IAA degradation, and the abundance of a series of proteins was upregulated to respond to the stress, including reaction oxygen species (ROS) scavenging, protein repair, fatty acid synthesis, RNA protection, signal transduction, chemotaxis, and several membrane transporters. The findings firstly explained the adaptation mechanism of bacteria to IAA degradation.
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PROCESS BIOCHEMISTRY
·
2020
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IF 2.952
Han Huang,Yun Lin,Guozeng Wang,Juan Lin
A new pullulanase-encoding gene, pulSL3 , was cloned from Alkalibacterium sp. SL3 and expressed in Escherichia coli . Deduced PulSL3 contains 2026 amino acid residues and consists of a putative signal peptide, four carbohydrate-binding modules, an E_set pullulanase domain, an α-amylase domain, and a pullulanase domain. The purified rPulSL3 exhibited pullulanase activity only. To identify the functions of the α-amylase and pullulanase domains, the N- and C-terminus truncated mutants ( pulSL3△N and pulSL3△C ) were also expressed in E. coli. The purified rPulSL3△N had pullulanase activity, while rPulSL3△C had no either α-amylase or pullulanase activity. Both rPulSL3 and rPulSL3△N exhibited maximum activities at pH 9.0 and 50 °C, and were highly active and stable at the concentration of NaCl up to 4 M and resistant to a few surfactants and detergents. In comparison to the wild type, rPulSL3△N had better thermostability (retaining 62.9 vs. 33.6% activity at 52 °C for 30 min), higher substrate affinity (with K m of 0.10 vs. 0.15 mg mL −1 ) and higher catalytic efficiency (836.6 vs. 520.3 mL mg −1 s −1 ). These excellent properties make rPulSL3△N potential for the application in the industries of detergent, food, and environmental remediation.
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SCIENCE OF THE TOTAL ENVIRONMENT
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2019
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IF 5.589
Zeyu Wang,Cong Chen,Huan Liu,Dzmitry Hrynshpan,Tatsiana Savitskaya,Jianmeng Chen,Jun Chen
The microbial reduction of nitrate in the presence of nanoscale zero-valent iron (nZVI) was evaluated to assess the feasibility of employing nZVI for biological denitrification treatment. The effect of modified nZVI on the growth, metabolism, and denitrification performance of Alcaligenes sp. TB under aerobic conditions was studied. Results showed that Alcaligenes sp. TB with nZVI/Pd had 31.5% increase in nitrate removal and 18.1% decrease in nitrite accumulation within 28 h. nZVI/Pd exhibited less inhibition on the cell growth (OD 600 = 0.725), NADH/NAD + ratio (86% of control), and electron transfer system activity (68.5% of control). In addition, nZVI/Pd decreased the membrane fluidity by increasing the trans/cis isomerization ratio (317.7% of control) to enhance the resistance of nZVI. This study underlines the effects of nZVI/Pd on membrane susceptibility via membrane fatty acid transformation during denitrification and suggests the influence of engineered nanomaterials on denitrification.
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LWT-FOOD SCIENCE AND TECHNOLOGY
·
2019
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IF 3.714
Xi Cao,Linmeng Liao,Fengqin Feng
Lipase catalysis has become the most promising technique for enrichment of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) due to its mild and green conditions. In this study, Trichosporon sp. F1-2 was newly isolated from oil-contaminated sludge, and its extracellular lipase was purified using ammonium sulfate precipitation and DEAE-Sepharose chromatography. The molecular weight of the lipase was estimated to be 32.6 kDa. The optimal temperature and pH for lipase activity were 50 °C and 8.0, respectively, and the optimal storage conditions were found to be temperatures below 45 °C and pH 7.0–9.0. The lipase did not require metal ions as cofactors and was significantly inhibited by Zn 2+ . It was stable in various organic solvents with different log P values, and n-hexane, toluene, dichloromethane, diethyl ether and glycerol even enhanced its activity. It had sn -1,3 regioselectivity and the highest activity towards a medium-chain fatty acid (C8) ester. This study demonstrated the lipase has good potential as a catalyst in enrichment of EPA and DHA in fish oil. The content of EPA and DHA reached 22.9 and 25.4 mol%, respectively, using 100 U of the lipase within 24 h, and the enrichment efficiency of DHA was higher than that of EPA.
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JOURNAL OF MOLECULAR LIQUIDS
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2024
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IF 5.3
Fanjin Meng,Xin Ju,Yuyang Zhou,Lishi Yan,Zhi Chen,Yuqiu Wu,Liangzhi Li
The two major impediments to biomass resourcing are the catalytic efficiency of enzymes and the effectiveness of biomass pretreatment. In this study, six genes encoding β-Glucosidases (BGLs) derived from Paenibacillus sp. LLZ1 were cloned and expressed. The activity of BGL-F, which had the highest enzyme activity, was 24.1 U/mg, which was 39.8–83.7% higher than that of the other BGLs. Molecular docking and surface charge analyses showed that the binding energy of BGL-F to cellobiose and its electronegative ligand-binding pocket were greater than those of other BGLs. On the other hand, by calculating and comparing the Kamlet–Taft (KT) values of deep eutectic solvent (DES) composed of different hydrogen bond donors (HBD) and hydrogen bond acceptors (HDA), it was found that DES composed of betaine and glycerol had the highest α value of 0.97, meaning that it could provide the highest hydrogen bonding capacity, and thus it had the best pretreatment effect on biomass. Analysis by circular dichroism (CD) spectroscopy revealed a decrease in α-helix and an increase in β-strand in the secondary structure of the DES-treated BGL-F, implying an increase in enzyme activity and stability. This result was also confirmed experimentally by the fact that the K m and V max of the enzyme in the DES system increased by 13.2% and 57.9%, respectively, and the inactivation rate (k d ) decreased by 21.4%. The results of this study showed that DES consisting of glycerol-betaine achieved a better balance between the promotion of enzyme activity and biomass pretreatment.
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ENVIRONMENTAL GEOCHEMISTRY AND HEALTH
·
2024
·Vol. 46
·期 9
·1-17
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IF 3.2
Zhong Bin,Xie Hanyi,Pan Tao,Su Buli,Xu Weijun,Wu Zhenqiang
Highly acidic citrus pomace (CP) is a byproduct of Pericarpium Citri Reticulatae production and causes significant environmental damage. In this study, a newly isolated acid-tolerant strain of Serratia sp. JS-043 was used to treat CP and evaluate the effect of reduced acid citrus pomace (RACP) in passivating heavy metals. The results showed that biological treatment could remove 97.56% of citric acid in CP, the organic matter in the soil increased by 202.60% and the catalase activity in the soil increased from 0 to 0.117 U g −1 . Adding RACP into soil can increase the stabilization of Cu, Zn, As, Co, and Pb. Specifically, through the metabolism of strain JS-043, RACP was also involved in the stabilization of Zn and Pb, and Residual Fraction in the total pool of these metals increased by 10.73% and 10.54%, respectively. Finally, the genome sequence of Serratia sp. JS-043 was completed, and the genetic basis of its acid-resistant and acid-reducing characteristics was preliminarily revealed. JS-043 also contains many genes encoding proteins associated with heavy metal ion tolerance and transport. These findings suggest that JS-043 may be a high-potential strain to improve the quality of acidic organic wastes that can then be useful for soil bioremediation. Graphical Abstract
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2024
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IF 5.7
Junwei Huang,Zilin Zhu,Ruomu Chen,Dandan Pan,Qing X. Li,Xiangwei Wu
Ibuprofen, a widely used nonsteroidal anti-inflammatory drug, contaminates agricultural products and potentially threatens human health due to its frequent detection and poor biodegradability. Microbial metabolism dominates the elimination of residual ibuprofen in the environment. In mineral salt medium at pH 6 with 5 mM glucose, Streptomyces sp. D218 transformed ibuprofen concentrations ranging from 0.05 to 0.40 mM in 24 h. The optimal temperature, pH, and initial OD600 nm for ibuprofen transformation by strain D218 were 25–37 °C, 5.0–6.0, and 1.0–1.5, respectively. Strain D218 could simultaneously transform ibuprofen into the intermediates 2-hydroxyibuprofen and ibuprofen amide (IBUA). The two intermediates were further metabolized to 2-hydroxyibuprofen amide (2HIBUA), thus relieving the growth inhibition of ibuprofen in Scenedesmus obliquus. This is the first complete pathway reported for the detoxification of ibuprofen transformation by a Gram-positive strain. These findings further our understanding of the microbial catabolism of the IBU.
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mSphere
·
2024
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IF 3.7
Wenxuan Liu,Fulong Nan,Fengjun Liu,Xiaoli Yang,Zonghui Li,Shasha Jiang,Xianjuan Zhang,Jun Li,Meng Yu,Yunyang Wang,Bin Wang
Hyperuricemia has become the second most prevalent metabolic disease after diabetes, but the limitations of urate-lowering treatment (ULT) drugs and patient nonadherence make ULT far less successful. Thus, more ULT approaches urgently need to be explored. Uric acid-degrading bacteria have potential application value in ULT. In this study, we isolated 44XBT, a uric acid-degrading bacterium, from black-headed gull (Chroicocephalus ridibundus) feces. Using a polyphasic taxonomic approach, strain 44XBT was identified as a novel genus within the family Bacillaceae; subsequently, the name Aciduricibacillus chroicocephali was proposed. Strain 44XBT had a unique uric acid-dependent phenotype and utilized uric acid and allantoin as the sole carbon and nitrogen sources, but not common carbon sources or complex media. In the genome, multiple copies of genes involved in uric acid metabolic pathway (pucL, pucM, uraD, and allB) were found. Six copies of pucL (encoding urate oxidase) were detected. Of these, five pucL copies were in a tandem arrangement and shared 70.42%–99.70% amino acid identity. In vivo experiments revealed that 44XBT reduced serum uric acid levels and attenuated kidney damage in hyperuricemic mice through uric acid catalysis in the gut and gut microbiota remodeling. In conclusion, our findings discover a strain for studying bacterial uric acid metabolism and may provide valuable insights into ULT.
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