Foods
·
2021
·Vol. 11
·期 1
·92
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IF 4.35
Zhiling Tang,Haiming Chen,Ming Zhang,Zhuye Fan,Qiuping Zhong,Weijun Chen,Yong-Huan Yun,Wenxue Chen
Pseudomonas lundensisis the main bacterium responsible for meat spoilage and its control is of great significance. 3-Carene, a natural monoterpene, has been proved to possess antimicrobial activities. This study aimed to investigate the antibacterial activity and mechanism of 3-carene against the meat spoilage bacteriumP. lundensis, and explore its application on pork. After 3-carene treatment, cellular structural changes were observed. Cell walls and membranes were destroyed, resulting in the leakage of alkaline phosphatase and cellular contents. The decreased activity of Ca2+-Mg2+-ATPase and Na+-K+-ATPase showed the imbalance of intracellular ions. Subsequently, adenosine triphosphate (ATP) content and oxidative respiratory metabolism characteristics indicated that 3-carene inhibited the metabolism of the tricarboxylic acid cycle inP. lundensis. The results of binding 3-carene with the vital proteins (MurA, OmpW, and AtpD) related to the formation of the cell wall, the composition of the cell membrane, and the synthesis of ATP further suggested that 3-carene possibly affected the normal function of those proteins. In addition, the growth ofP. lundensisand increase in pH were inhibited in pork during the 5 days of cold storage after the samples were pre-treated with 3-carene. These results show the anti-P. lundensisactivity and mechanism of 3-carene, and its potential use in meat preservation under refrigerated conditions.Keywords:Pseudomonas lundensis;3-carene;preservatives;membrane damage
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ENVIRONMENTAL MICROBIOLOGY
·
2021
·Vol. 23
·期 6
·3265-3273
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IF 5.491
Mingliang Zhang,Yijun Ren,Shilong Du,Yidong Zhou,Wankui Jiang,Zhijian Ke,Mingli Jiang,Jiguo Qiu,Jian He,Qing Hong
Summary Pymetrozine is a synthetic pesticide that can be utilized as the sole carbon source by Pseudomonas sp. strain BYT-1. However, the genes involved in the degradation of pymetrozine remain unknown. We used transposon mutagenesis to create a mutant that unable to hydrolyze pymetrozine. The transposon interrupted the gene pyzH , which was cloned by self-formed adaptor PCR. PyzH hydrolyzed the C=N double bond of pymetrozine to produce 4-amino-6-methyl-4,5-dihydro-2 H -[1,2,4]triazin-3-one (AMDT) and nicotinaldehyde; the latter inhibits PyzH activity. PyzH can completely hydrolyze pymetrozine in the presence of dehydrogenase ORF6, which can convert nicotinaldehyde into nicotinic acid and relieve the inhibition. H 2 18 O-labeling experiments showed that the oxygen atom of nicotinaldehyde came from water instead of oxygen. PyzH homologous genes were also found in other soil isolates able to degrade pymetrozine.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2020
·
IF 7.1
Lulu Liu,Xujing Cao,Wenrui Ma,Li Chen,Shunbo Li,Baoshan Hu,Yi Xu
Pyocyanin is a specific virulence factor and quorum sensing (QS) signal molecule of Pseudomonas aeruginosa , and plays an important role in biofilm formation. In this paper, a biosensor chip was proposed and fabricated for the long term cultivation of Pseudomonas aeruginosa biofilms and in-situ monitoring of pyocyanin. The biosensor chip consisted of two parts, a top polydimethylsiloxane (PDMS) layer with micro-channels and micro-chambers for providing an adequate microenvironment for Pseudomonas aeruginosa biofilm growth, and a bottom microelectrode integrated on a glass substrate for monitoring the QS virulence factor and Pseudomonas aeruginosa biofilms. The concentration of pyocyanin was monitored by AuNPs-modified microelectrodes by differential pulse voltammetry (DPV) on the designed chip. It was demonstrated that the change in pyocyanin concentration was closely related to the developing process of the Pseudomonas aeruginosa biofilms. In addition, the effect of curcumin, a Chinese herb QS inhibitor, on pyocyanin and biofilm production was investigated and analyzed. The results indicate that curcumin inhibited the growth of Pseudomonas aeruginosa biofilms and reduced the production of pyocyanin. The designed biosensor chip provides a promising microenvironment for the quantitative monitoring of pyocyanin in the formation of biofilms and acts as a platform for investigating the mechanism behind anti-bacterial agents.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2020
·
IF 7.1
Xiaojun He,Zaian Deng,Wei Xu,Yahui Li,Chuchu Xu,Hong Chen,Jianliang Shen
Hypochlorite (ClO − ) and hydrazine (N 2 H 4 ) were poisonous to the biological environment. Accurate and sensitive identification of ClO − and N 2 H 4 in biological and environmental systems was essential to reveal their various physiological and pathological functions. Herein, a dual-response chemosensor, HNTBA , was developed for quantitative monitoring and visualization of ClO − and N 2 H 4 in vitro and in vivo via fluorescence turn-on strategy. With the addition of ClO − /N 2 H 4 , fluorescence “OFF–ON” response was obtained for the sensor as a result of specific ClO − /N 2 H 4 -triggered C C bond cleavage reaction with converted to the corresponding aldehyde and hydrazone, which responding mechanism was verified by DFT calculation. Additionally, HNTBA features rapid response (<30 s) and low limit of detection (nanomole), high sensitivity and selectivity toward ClO − /N 2 H 4 over other analytes, which allow it to be used for quantification of ClO − /N 2 H 4 in a simulated physiological condition. Fluorescence imaging using HNTBA sensor was taken to monitor the exogenous/endogenous ClO − levels in hPDLCs and RAW 264.7 cells in a concentration-dependent manner. Notably, HNTBA exhibits high effectiveness for early assessment of the treatment response of ClO − -mediated in cells with N-acetylcysteine ( NAC ) and lipopolysaccharide (LPS). Moreover, HNTBA can be used to visualize N 2 H 4 in live cells from blue channels with good performance. The outstanding sensing performances of HNTBA sensor enabled fast tracking of ClO − and N 2 H 4 in Pseudomonas aeruginosa and zebrafish with fluorescence light up, and it could be further applied to a paper strip. The results demonstrate that HNTBA was a powerful tool to monitor ClO − and N 2 H 4 in biosystems and environmental.
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JOURNAL OF HAZARDOUS MATERIALS
·
2025
·
IF 11.3
Tingting Wang,Jiawei Jing,Pengfei Huang,Xinyu Guo,Chuan Li,Yuanyuan Qu
Remediation of soil contaminated with long–chain hydrocarbons and affected by salinization poses a considerable challenge. The isolation of a bacterial strain, identified as Pseudomonas aeruginosa DL, from petroleum–contaminated saline–alkali soil has been reported in this study. The strain demonstrated a high capacity to degrade long–chain alkanes and exhibited adaptability to saline–alkali conditions. Gene annotation and analysis of degradation products revealed that the strain DL employed a step–by–step chain–breaking mechanism to degrade long–chain alkanes. Following 160 days of bioaugmented remediation of contaminated soil using the strain DL, 81.36 % degradation of long–chain alkanes, initially present at a concentration of 30,000 mg/kg, was achieved. The activities of soil enzymes, including dehydrogenase, lipase, catalase, and urease, were significantly increased ( p < 0.05). Community structure analysis revealed that Pseudomonas aeruginosa DL successfully colonized the contaminated soil, achieving a relative abundance of 69 %. In addition, alkane–degrading bacterial genera, such as Salinimicrobium , Isoptericola , Gordonia , Achromobacter and Ochrobactrum , emerged as new dominant genera. Microbial cooccurrence networks confirmed that bioaugmentation with the strain DL could streamline interpopulation interactions within the community and enhance associative networks, thereby guiding community evolution toward improved alkane degradation. This study offers valuable strain resources and data support for the bioremediation of saline–alkali soils contaminated with long–chain alkanes.
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BMC MICROBIOLOGY
·
2016
·Vol. 16
·期 1
·1-11
·
IF 2.581
Wang Dan,Zhu Fengqiu,Wang Qian,Rensing Christopher,Yu Peng,Gong Jing,Wang Gejiao
Background Microbial antimonite [Sb(III)] oxidation converts toxic Sb(III) into less toxic antimonate [Sb(V)] and plays an important role in the biogeochemical Sb cycle. Currently, little is known about the mechanisms underlying bacterial Sb(III) resistance and oxidation. Results In this study, Tn5 transposon mutagenesis was conducted in the Sb(III)-oxidizing strain Pseudomonas stutzeri TS44 to isolate the genes responsible for Sb(III) resistance and oxidation. An insertion mutation into gshA, encoding a glutamate cysteine ligase involved in glutathione biosynthesis, generated a strain called P. stutzeri TS44-gshA 540 . This mutant strain was complemented with a plasmid carrying gshA to generate strain P. stutzeri TS44-gshA-C. The transcription of gshA , the two superoxide dismutase (SOD)-encoding genes sodB and sodC as well as the catalase-encoding gene katE was monitored because gshA -encoded glutamate cysteine ligase is responsible for the biosynthesis of glutathione (GSH) and involved in the cellular stress defense system as are superoxide dismutase and catalase responsible for the conversion of ROS. In addition, the cellular content of total ROS and in particular H 2 O 2 was analyzed. Compared to the wild type P. stutzeri TS44 and TS44-gshA-C, the mutant P. stutzeri TS44-gshA 540 had a lower GSH content and exhibited an increased content of total ROS and H 2 O 2 and increased the Sb(III) oxidation rate. Furthermore, the transcription of sodB , sodC and katE was induced by Sb(III). A positive linear correlation was found between the Sb(III) oxidation rate and the H 2 O 2 content ( R
2 = 0.97), indicating that the accumulated H 2 O 2 is correlated to the increased Sb(III) oxidation rate. Conclusions Based on the results, we propose that a disruption of the pathway involved in ROS-protection allowed H 2 O 2 to accumulate. In addition to the previously reported enzyme mediated Sb(III) oxidation, the mechanism of bacterial oxidation of Sb(III) to Sb(V) includes a non-enzymatic mediated step using H 2 O 2 as the oxidant.
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ANTIMICROBIAL AGENTS AND CHEMOTHERAPY
·
2024
·Vol. 68
·期 3
·
IF 4.1
Xiaonan Zhang,Yan Wang,Sanwang Li,Feifan Xie,Hanxi Yi
Bacterial infections, including those caused by Pseudomonas aeruginosa, often lead to sepsis, necessitating effective antibiotic treatment like carbapenems. The key pharmacokinetic/pharmacodynamic (PK/PD) index correlated to carbapenem efficacy is the fraction time of unbound plasma concentration above the minimum inhibitory concentration (MIC) of the pathogen (%fT > MIC). While multiple targets exist, determining the most effective one for critically ill patients remains a matter of debate. This study evaluated meropenem’s bactericidal potency and its ability to combat drug resistance in Pseudomonas aeruginosa under three representative PK/PD targets: 40% fT > MIC, 100% fT > MIC, and 100% fT > 4× MIC. The hollow fiber infection model (HFIM) was constructed, validated, and subsequently inoculated with a substantial Pseudomonas aeruginosa load (1 × 108 CFU/mL). Different meropenem regimens were administered to achieve the specified PK/PD targets. At specified intervals, samples were collected from the HFIM system and subjected to centrifugation. The resulting supernatant was utilized to determine drug concentrations, while the precipitates were used to track changes in both total and drug-resistant bacterial populations over time by the spread plate method. The HFIM accurately reproduced meropenem’s pharmacokinetics in critically ill patients. All three PK/PD target groups exhibited a rapid bactericidal response within 6 h of the initial treatment. However, the 40% fT > MIC and 100% fT > MIC groups subsequently showed bacterial resurgence and resistance, whereas the 100% fT > 4× MIC group displayed sustained bactericidal activity with no evidence of drug resistance. The HFIM system revealed that maintaining 100% fT > 4× MIC offers a desirable microbiological response for critically ill patients, demonstrating strong bactericidal capacity and effective prevention of drug resistance.
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BIORESOURCE TECHNOLOGY
·
2019
·
IF 6.669
Lei Yang,Xu-Hui Wang,Shen Cui,Yong-Xiang Ren,Jie Yu,Ning Chen,Qian Xiao,Lin-Kai Guo,Rui-Hua Wang
A novel strain NP5 with efficient heterotrophic nitrification, aerobic denitrification and phosphorus accumulation ability was isolated and identified as Pseudomonas putida strain NP5. The removed ammonium and phosphate were mainly converted into intracellular components by assimilation, and negligible nitrification intermediates and N 2 O were accumulated during heterotrophic nitrification. In addition, the optimal conditions for nutrient removal were: succinate as carbon source, C/N 10, P/N 0.2, temperature 30 °C, salinity 0% and shaking speed 160 rpm. Besides, strain NP5 possessed an exceptional heavy metal and nanoparticles resistance. Cr 6+ was found to be the most toxic among the tested metals, and it could be removed simultaneously. Moreover, an obvious phosphorus release was observed under anaerobic condition, and repeated exposure to the anaerobic/aerobic conditions could significantly improve the nutrient removal. Furthermore, the successful expression of key enzymes for nitrogen and phosphorous removal provided additional evidence for possibility of simultaneous nitrification, denitrification and phosphorus removal.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2022
·
IF 5.895
Ya’nan Shi,Rongshan Li,Jie Zheng,Yubin Xue,Yong Tao,Bo Yu
Bio-based propionate attracts increasing attention owing to its green nature and specific food additive market. To date, the time-consuming and costly fermentation process by strict anaerobes makes propionate production not ideal. In this study, we designed a new route for propionate production, in which 1,2-propanediol was first dehydrated to propionaldehyde and then to propionate by taking advantage of the robust oxidization capacity of the Pseudomonas putida KT2440 strain. The high atom economy (0.97 g/g) in this proposed pathway is more advantageous than the previous l-threonine-derived route (0.62 g/g). The molecular mechanism of the extraordinary oxidation capacity of P. putida KT2440 was first deciphered. The propionate production was realized in P. putida KT2440 by screening suitable glycerol dehydratases and optimizing the expression to eliminate the formation of 1-propanol and the accumulation of the intermediate propionaldehyde. The engineered strain produced propionate with a molar conversion rate of >99% from 1,2-propanediol. A high titer of 46.5 g/L pure propionic acid with a productivity of 1.55 g/L/h and a mass yield of 0.96 g/g was achieved in fed-batch biotransformation. Thus, this study provides another idea for the production of high-purity bio-based propionate from renewable materials with high atom economy.
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JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2017
·Vol. 93
·期 6
·1618-1626
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IF 3.135
Sheng-Jie Yue,Muhammad Bilal,Shu-Qi Guo,Hong-Bo Hu,Wei Wang,Xue-Hong Zhang
BACKGROUND Trans -2, 3-dihydro-3-hydroxyanthranilic acid (DHHA) is a valuable metabolic intermediate for the biosynthesis of wide-ranging benzoic acid derivatives with enormous biological or pharmaceutical activities. Pseudomonas chlororaphis GP72 is a non-pathogenic biocontrol strain that displays unique capability to produce phenazines. Nevertheless, DHHA production is quite low by the wild type strains, which necessitates yield improvement by constructing engineered strains for large-scale biotechnological applications. RESULTS In this study, two negative regulatory genes namely rsmE and lon were successively deactivated in the DA4 strain. The resulting engineered DA6 strain produced a significantly high titer of DHHA (20.6% higher than that of DA4). The influence of varying pH from 6.2 to 8.2 on DHHA production was studied in a 6-L benchtop fermenter. A controlled broth pH of 7.2 stimulated maximum DHHA production by the engineered DA6 strain. A DO-stat based fed-batch system maintaining a constant DO level (about 20%) accompanied by a glycerol feeding strategy was applied. Highest DHHA production using this approach was recorded to be 10.06 g L -1 , which was 31% higher than with traditional batch cultivation. CONCLUSION The production of DHHA in metabolically engineered GP72 was considerably improved by inactivating two negative regulatory genes in a fed-batch mode. It is concluded that fed-batch fermentation with intermittent glycerol feeding and pH-control was an effective approach to improve DHHA production yield. © 2017 Society of Chemical Industry
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JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Zhao Wang,Junfeng Su,Amjad Ali,Ruijie Zhang,Wenshuo Yang,Liang Xu,Tingbao Zhao
A simultaneous denitrifying and mineralizing bacterium, Pseudomonas sp. WZ39 was isolated for fluoride (F − ), nitrate (NO 3 − -N), and calcium (Ca 2+ ) removal. Strain WZ39 exhibited a remarkable defluoridation efficiency of 87.49% under a pH of 6.90, F − and Ca 2+ concentration of 1.99 and 201.88 mg L −1 , respectively. EEM, SEM–EDS, XRD, and FTIR analyses elucidated the chemical adsorption and co-precipitation with calcium salt contributed to the removal of F − . The mechanisms of biomineralization were also investigated by determining the role of bound and unbound extracellular polymeric substances (EPS), cell wall, and calcium channel in nucleation. The results showed that bacteria can promote nucleation on the templates of cell walls or EPS through the electrostatic effect. The presence of the calcium channel blocker inhibited the transport of intracellular Ca 2+ to the extracellular environment. The outcome of the present research can provide a theoretical basis for the understanding of MICP phenomenon and the efficient treatment of F − containing groundwater.
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Microbiology Spectrum
·
2022
·Vol. 10
·期 5
·
IF 9.043
Wen Wang,Xuerui Bao,Mona Bové,Petra Rigole,Xiaofeng Meng,Jianyu Su,Tom Coenye
Phytochemicals are promising antibacterials for the development of novel antibiofilm drugs, but their antibiofilm activity in physiologically relevant model systems is poorly characterized. As the host microenvironment can interfere with the activity of the phytochemicals, mimicking the complex environment found in biofilm associated infections is essential to predict the clinical potential of novel phytochemical-based antimicrobials. In the present study, we examined the antibiofilm activity of borneol, citral, and combinations of both as well as their Pickering emulsions against Staphylococcus aureus and Pseudomonas aeruginosa in an in vivo-like synthetic cystic fibrosis medium (SCFM2) model, an in vitro wound model (consisting of an artificial dermis and blood components at physiological levels), and an in vivo Galleria mellonella model. The Pickering emulsions demonstrated an enhanced biofilm inhibitory activity compared to both citral and the borneol/citral combination, reducing the minimum biofilm inhibitory concentration (MBIC) values up to 2 to 4 times against P. aeruginosa PAO1 and 2 to 8 times against S. aureus P8-AE1 in SCMF2. In addition, citral, the combination borneol/citral, and their Pickering emulsions can completely eliminate the established biofilm of S. aureus P8-AE1. The effectiveness of Pickering emulsions was also demonstrated in the wound model with a reduction of up to 4.8 log units in biofilm formation by S. aureus Mu50. Furthermore, citral and Pickering emulsions exhibited a significant degree of protection against S. aureus infection in the G. mellonella model. The present findings reveal the potential of citral- or borneol/citral-based Pickering emulsions as a type of alternative antibiofilm candidate to control pathogenicity in chronic infection.IMPORTANCE There is clearly an urgent need for novel formulations with antimicrobial and antibiofilm activity, but while there are plenty of studies investigating them using simple in vitro systems, there is a lack of studies in which (combinations of) phytochemicals are evaluated in relevant models that closely resemble the in vivo situation. Here, we examined the antibiofilm activity of borneol, citral, and their combination as well as Pickering emulsions (stabilized by solid particles) of these compounds. Activity was tested against Staphylococcus aureus and Pseudomonas aeruginosa in in vitro models mimicking cystic fibrosis sputum and wounds as well as in an in vivo Galleria mellonella model. The Pickering emulsions showed drastically increased antibiofilm activity compared to that of the compounds as such in both in vitro models and protected G. mellonella larvae from S. aureus-induced killing. Our data show that Pickering emulsions from phytochemicals are potentially useful for treating specific biofilm-related chronic infections.
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