BIORESOURCE TECHNOLOGY
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2024
·
IF 9.7
Shengyong Jia,Yanfang Diao,Yingying Li,Jingshen Zhang,Hongjun Han,Guirong Li,Yuanhu Pei
The Escherichia coli ( E.coli ) degrading glucose irradiated by ultrasound irradiation (20 W, 14 min) was investigated as the model system, the glucose degradation increased by 13 % while the E.coli proliferation decreased by 10 % after culture for 18 h. It indicated a tradeoff effect between substrate degradation and cell proliferation, which drove the enhanced contaminants removal and excess sludge reduction in a weak ultrasound enhanced biological wastewater treatment. The enzymatic activities (catalase, superoxide dismutase, adenosine triphosphatases, lactic dehydrogenase, membrane permeability, intracellular reactive oxygen species and calcium ion of E. coli increased immediately by 12 %, 63 %, 124 %, 19 %, 15 %, 4-fold and 38-fold, respectively by ultrasound irradiation power of 20 W for 14 min. Furthermore, the membrane permeability of irradiated E. coli increased by 26 % even though the ultrasound stopped for 10 h. Additionally, pathways associated with glucose degradation and cell proliferation were continuously up-regulated and down-regulated, respectively.
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ANALYTICAL CHEMISTRY
·
2024
·
IF 6.7
Xi Long,Zan Gong,Yuqing Gan,Panpan Yuan,Yalan Tang,Yanjing Yang,Shian Zhong
Pathogens pose a serious threat to public and population health, leading to serious outbreak and spread of diseases irrespective of the region. The capability to directly, sensitively, and specifically detect viable pathogens in low numbers in food and clinical samples is very desirable but remains a challenge. In this work, we present a novel assay of a combination of an aptamer-based allosteric probe and hairpin switch-controlled T7 RNA polymerase-based isothermal transcription amplification, which enables rapid, ultrasensitive, label-free detection of direct pathogens. It can detect Escherichia coli as low as 73.2 CFU/mL. Moreover, with the usage of the proposed assay, sensitive quantification of E. coliO157:H7 in milk samples has been achieved, showing significant potential as a simple and sensitive tool to quantify pathogens in milk and other foods.
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ENGINEERING IN LIFE SCIENCES
·
2019
·Vol. 19
·期 4
·270-278
·
IF 1.936
Jinyuan Hu,Xiao Lu,Haokun Wang,Fuxiang Wang,Yuan Zhao,Wei Shen,Haiquan Yang,Xianzhong Chen
d -Alanyl- d -alanine carboxypeptidase DacC is important for synthesis and stabilization of the peptidoglycan layer of Escherichia coli . In this work, dacC of E . coli BL21 (DE3) was successfully deleted, and the effects of this deletion on extracellular protein production in E . coli were investigated. The extracellular activities and fluorescence value of recombinant amylase, green fluorescent protein, and α-galactosidase of the deletion mutants were increased by 82.3, 29.1, and 37.7%, respectively, compared with that of control cells. The outer membrane permeability and intracellular soluble peptidoglycan accumulation of deletion mutant were also enhanced compared with those of control cells, respectively. Based on fluorescence-assisted cell sorting analyses, we found that the morphology of the E. coli deletion mutant cells was altered compared with that of control cells. Local transparent bulges in the poles of the E . coli mutant with deletion of the dacC gene were found by transmission electron microscopy analysis. These bulges in the poles could explain the improvement in the production of extracellular protein by the E. coli mutant with deletion of the dacC gene. These findings provide important insights into the extracellular production of proteins using E . coli as microbial cell factories.
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APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2018
·Vol. 187
·期 4
·1143-1157
·
IF 1.797
Jin Li-Qun,Xu Wei,Yang Bo,Liu Zhi-Qiang,Zheng Yu-Guo
Xylitol is an important functional sugar alcohol which is widely used in industries. To efficiently produce xylitol from xylose by xylose reductase in a single step, the coupled system and the coexpression system using xylose reductase (XR) from Rhizopus oryzae and glucose dehydrogenase (GDH) from Exiguobacterium sibiricum were constructed, the latter of which was used for cofactor regeneration. One hundred fifty grams/liter of xylose could be fully converted to xylitol by employing the two-enzyme coupled system with cell-free extract, and xylitol productivity of 21.2 g/L/h was reached by biotransformation in vitro. The whole-cell biocatalyst coexpressing xylose reductase and glucose dehydrogenase was successfully used to synthesize xylitol via enzymatic reduction of xylose. After optimization of the induction condition, the enzyme activity reached 1533 U/L. Two hundred grams/liter of xylose could be completely converted to xylitol, and the highest xylitol productivity of 6.37 g/L/h was obtained under the optimal transformation conditions. Thus, recombinant Escherichia coli coexpressing xylose reductase and glucose dehydrogenase is a promising candidate for xylitol production from xylose.
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PROTEIN AND PEPTIDE LETTERS
·
2021
·Vol. 28
·期 12
·1391-1397
·
IF 1.89
Zhang Xing-Jie,Wang Ting-Ting,Pu Yu-Kun,Zeng Lin,Zhang Rui-Han,Li Xiao-Li,Ji Xu,Xiao Wei-Lie
Background: NIMA (never in mitosis, gene A) serine/threonine kinase 7 (NEK7) is a regulator of mitosis spindle in mammals and is considered as a drug target of inflammasome related inflammatory diseases. However, most commercially available or reported recombinant NEK7 proteins are
either inactive or have low purity. These shortcomings limit the pharmacological studies and development of NEK7 inhibitors. Objective: To elucidate what causes the NEK7 low purity in E. coli, and optimize a protocol to improve the protein purity. Methods: A comparative
study of expression full length NEK7 with an N-terminal His-tag or a Cterminal His-tag was performed. His-affinity resin, ion exchange and gel filtration chromatography were used to purify NEK7. The protein was identified by mass spectrometry. The activity and folding of NEK7 were evaluated
by chemiluminescent assay and thermal shift assay. Results: Our results demonstrated that N-terminal tagged protein was toxic to E. coli, resulting in incomplete translated products. The C-terminal tagged NEK7-His6 had a much higher purity than that of an N-terminal
tag. The Ni2+ resin one-step purification led to a purity of 91.7%, meeting the criteria of most kinase assays. With two-step and three-step procedures, the protein purities were 94.7% and ~100%, respectively. The NEK7 purified in this work maintained its kinase activity
and correct conformation, and the compound-protein interaction ability. Conclusion: Our optimized protocol could produce good purity of His tagged NEK7 in E. coli, and the kinase activity and biophysical characteristics of which are preserved.
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ENZYME AND MICROBIAL TECHNOLOGY
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2022
·
IF 3.705
Ting Zhang,Qiang Zhou
The apparent solubility and bioavailability of hydrophobic compounds, the main problems in the bioremediation process, can be overcome by bacteria producing biosurfactants. Lipopeptide biosurfactants, as high-efficiency biosurfactants with biological activity, can be synthesized by nonribosomal peptide synthetase (NRPS). In this study, two strains, Paenibacillus lautus A (HC_A) and Lysinibacillus fusiformis B (HC_B), which can efficiently produce lipopeptide biosurfactants, were screened. The NRPS gene sequences of these two strains were obtained by whole-genome sequencing. The module of synthetic surfactant NRPS from HC_A and the module of synthetic surfactants NRPS and sfp from HC_B were successfully cloned into plasmids and then expressed in E. coli (namely, E. coli pHC_A-NRPS and E. coli pHC_B-NRPS-sfp , respectively). Finally, stable lipopeptide biosurfactants could be expressed heterologously. Our research shows that the constructed recombinant bacteria E. coli pHC_A-NRPS and E. coli pHC_B-NRPS-sfp can heterologously express the NRPS module (graphical abstract is shown in Fig 1). Remarkably, the lipopeptide biosurfactants produced by the constructed recombinant bacteria of the NRPS gene have good emulsifying activity on tributyrin. Meanwhile, adding SiO 2 nanoparticles and surface-modified carbon black can synergistically enhance the emulsifying effect, which has not been reported before. This research may deepen the comprehension of microbial strains that produce surfactants to emulsify environmental pollutants and perform bioremediation.
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iScience
·
2024
·Vol. 27
·期 2
·108818-108818
·
IF 4.6
Manlu Zhu,Haoyan Mu,Xiongfeng Dai
To thrive in nature, bacteria have to reproduce efficiently under favorable conditions and persist during stress. The global strategy that integrates the growth control and stress response remains to be explored. Here, we find that a moderate induction of (p)ppGpp reduces growth rate but significantly enhances the stress tolerance of E. coli , resulting from a global resource re-allocation from ribosome synthesis to the synthesis of stress-responsive proteins. Strikingly, the activation of stress response by (p)ppGpp is still largely retained in the absence of RpoS. In addition, (p)ppGpp induction could activate the catabolism of alanine and arginine, facilitating the adaption of bacteria to nutrient downshift. Our work demonstrates that the activation of stress response by (p)ppGpp could occur in an RpoS-independent manner and (p)ppGpp enables bacteria to integrate the control of growth and stress response in a seesaw fashion, thus acting as an important global regulator of the bacterial fitness landscape.
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ENZYME AND MICROBIAL TECHNOLOGY
·
2024
·
IF 3.4
Caixia Pei,Xinlv Peng,Yiran Wu,Runmiao Jiao,Tiehai Li,Siming Jiao,Lei Zhou,Jianjun Li,Yuguang Du,Eika W. Qian
Eukaryotic sialyltransferases play key roles in many physiological and pathological events. The expression of active human recombinant sialyltransferases in bacteria is still challenging. In the current study, the genes encoding human N -acetylgalactosaminide α2,6-sialyltransferase V (hST6GalNAc V) and N -acetylgalactosaminide α2,6-sialyltransferase VI (hST6GalNAc VI) lacking the N -terminal transmembrane domains were cloned into the expression vectors, pET-32a and pET-22b, respectively. Soluble and active forms of recombinant hST6GalNAc V and hST6GalNAc VI when coexpressed with the chaperone plasmid pGro7 were successfully achieved in Escherichia coli . Further, lactose (Lac), Lacto- N -triose II (LNT II), lacto- N -tetraose (LNT), and sialyllacto- N -tetraose a (LSTa) were used as acceptor substrates to investigate their activities and substrate specificities. Unexpectedly, both can transfer sialic acid onto all those substrates. Compared with hST6GalNAc V expressed in the mammalian cells, the recombinant two α2,6-sialyltransferases in bacteria displayed flexible substrate specificities and lower enzymatic efficiency. In addition, an important human milk oligosaccharide disialyllacto- N -tetraose (DSLNT) can be synthesized by both human α2,6-sialyltransferases expressed in E. coli using LSTa as an acceptor substrate. To the best of our knowledge, these two active human α2,6-sialyltransferases enzymes were expressed in bacteria for the first time. They showed a high potential to be applied in biotechnology and investigating the molecular mechanisms of biological and pathological interactions related to sialylated glycoconjugates.
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CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Huiying Liao,Shuang Liu,Xing Sun,Zezhong Huang,Yun Sun,Juan Guo,Fengying Li,Bolong Xu
The development of colorectal cancer is closely related to the abnormal colonization of specific microorganisms in the tumor microenvironment. To address the challenges of exacerbated carcinogenesis and therapeutic resistance caused by Escherichia coli colonization in colorectal tumors, an innovative pH- and targeting-dual-responsive biomimetic nanodelivery system (CIP@EMV@CaCO 3 ) based on bacterial membrane biomimetic strategies was developed. This system employs E. coli -derived membrane vesicles (EMVs) as carriers to achieve dual functions of homologous targeting for antibacterial purposes and immune activation, overcoming the low delivery efficiency bottleneck of traditional antibiotics. The innovative incorporation of calcium carbonate (CaCO 3 ) enables both acidic environment-triggered lysosomal escape mediated by CO 2 microbubbles and immunotoxicity regulation, achieving a bacterial clearance rate of 99.14 %. Furthermore, the EMVs themselves were demonstrated to activate potent antitumor immune responses, inducing M1 macrophage polarization, promoting cytokine secretion, and enhancing T lymphocyte infiltration, resulting in a 98.02 % tumor suppression rate in E. coli -infected colorectal cancer models. This study provides a multifunctional precision therapeutic paradigm for regulating microbe-tumor interactions, demonstrating significant translational value in the synergistic field of targeted antibacterial and immune therapy.
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ACS Synthetic Biology
·
2025
·
IF 3.9
Hong-Rui Li,Ying Zhou,Bang-Ce Ye
Bacteriophages, leveraging phage display and chemical modification, have the potential to deliver large payloads of antitumor agents with precision and to advance vaccine development. However, systemic phage administration often induces neutralizing antibodies, which accelerate phage clearance and reduce accumulation at the target site. To address this limitation, we propose a genetically modified nonpathogenic bacterial strain that specifically targets tumors and releases programmed death ligand 1 (PD-L1)-specific M13 bacteriophage within tumor tissue. We assessed the antitumor efficacy of this phage-expressing strain as an adjunctive therapeutic strategy along with a therapeutic bacterial strain engineered for the controlled release of an immunotoxin. The combination of these strains demonstrated synergistic effects in eliciting antitumor immune responses and inhibiting tumor growth in a murine model of colorectal cancer (CRC). Moreover, when combined with Folfox, the phage-expressing strain significantly extended the survival. This strategy of in vivo expression and tumor-specific release mediated by nonpathogenic bacterial strains provides an effective and safe method for targeted therapeutic phage delivery to tumors.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2020
·
IF 6.551
Xiaoting Qian,Zhouhang Gu,Qing Tang,Aimei Hong,Juliane Filser,Virender K. Sharma,Lingxiangyu Li
Nanoscale zinc oxide (n-ZnO) with different morphology and sizes has been used in personal care products due to their antibacterial properties, resulting in discharge of n-ZnO into the environment with potential toxic effect to ecological systems. Sulfidation is one of pathways of transformation of n-ZnO, but a very limited information on the conversion of n-ZnO under sulfidic environment with special morphology such as sea urchin-like zinc oxide nanospheres (ZnO-NSs) is available to know the potential environmental risks of n-ZnO. Herein, sea urchin-like ZnO-NSs with an average size of 78 nm were synthesized and adopted as the model n-ZnO of special morphology. The ZnO-NPs at average sizes of 71 nm (ZnO-NPs-71), 48 nm (ZnO-NPs-48), and 17 nm (ZnO-NPs-17) nm were used to examine possible differences in the sulfidation between the sea urchin-like ZnO-NSs and ZnO-NPs. A new analytical method selectively dissolving ZnO over ZnS in partially sulfidized n-ZnO was developed and applied to understand the kinetics of n-ZnO sulfidation. The sulfidation rate constant ( k s ) of sea urchin-like ZnO-NSs was 2.9 × 10 −3 h −1 , comparable to that of ZnO-NPs-71 (4.1 × 10 −3 h −1 ), but much lower than those of ZnO-NPs-48 (20.1 × 10 −3 h −1 ) and ZnO-NPs-17 (67.8 × 10 −3 h −1 ). This might be attributed to the differences in the specific surface area; k s positively correlated with the specific surface area ( R 2 = 0.97). Natural organic matter (NOM) decreased dissolution and sulfidation of the sea urchin-like ZnO-NSs. Aggregate ZnS nanocrystals instead of the original sea urchin-like ZnO-NSs were observed. We proposed that sea urchin-like ZnO-NSs were transformed to ZnS through a dissolution-precipitation pathway, consistent with the sulfidation pathway of ZnO-NPs. Sulfidation drastically reduced toxicity of sea urchin-like ZnO-NSs to Escherichia coli due to negligible dissolution of ZnS nanocrystals. These results greatly improved our understanding of the transformation and potential risks of n-ZnO with special morphology.
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MATERIALS CHEMISTRY AND PHYSICS
·
2014
·
IF 2.129
Jing Huang,Yi Liu,Yuxin Liu,Hua Li
Titania-hydroxyapatite (HA) nanocomposites were fabricated by wet chemical synthesis approach. HA exhibited crystallographic orientation of nucleation on nano titania particle, forming the composite particles with titania being partially enwrapped with HA. Microstructural characterization by high resolution transmission electron microscopy revealed coherent interfacial bond of (110) and (222) planes of HA crystal with (101) plane of anatase . The HA layer promoted significantly recruitment of Escherichia coli bacteria onto the titania-based particles for subsequent photocatalytic killing. Less extent of enwrapping of HA on titania particle, as accomplished by increasing the aging time of HA suspension, gave rise to better capability of photocatalytic degradation of methylene blue and sterilization of the bacteria. The novel HA-enwrapped titania powder shows great potential for environmental applications.
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