查找使用阿拉丁产品的科研文献

Volatile organic compounds produced by Pseudomonas fluorescens WR-1 restrict the growth and virulence traits of Ralstonia solanacearum

Waseem Raza,Ning Ling,Dongyang Liu,Zhong Wei,Qiwei Huang,Qirong Shen

The volatile organic compounds (VOCs) produced by soil microbes have a significant role in the control of plant diseases and plant growth promotion. In this study, we examined the effect of VOCs produced by Pseudomonas fluorescens strain WR-1 on the growth and virulence traits of tomato wilt pathogen Ralstonia solanacearum . The VOCs produced by P. fluorescens WR-1 exhibited concentration dependent bacteriostatic effect on the growth of R. solanacearum on agar medium and in infested soil. The VOCs of P. fluorescens WR-1 also significantly inhibited the virulence traits of R. solanacearum . The proteomics analysis showed that the VOCs of P. fluorescens WR-1 downregulated cellular proteins of R. solanacearum related to the antioxidant activity, virulence, inclusion body proteins, carbohydrate and amino acid synthesis and metabolism, protein folding and translation, methylation and energy transfer, while the proteins involved in the ABC transporter system, detoxification of aldehydes and ketones, protein folding and translation were upregulated. This study revealed the significance of VOCs of P. fluorescens WR-1 to control the tomato wilt pathogen R. solanacearum . Investigation of the modes of action of biocontrol agents is important to better comprehend the interactions mediated by VOCs in nature to design better control strategies for plant pathogens.

HipH Catalyzes the Hydroxylation of 4-Hydroxyisophthalate to Protocatechuate in 2,4-Xylenol Catabolism by Pseudomonas putida NCIMB 9866

Hong-Jun Chao,Yan-Fei Chen,Ti Fang,Ying Xu,Wei E. Huang,Ning-Yi Zhou

In addition to growing on p-cresol, Pseudomonas putida NCIMB 9866 is the only reported strain capable of aerobically growing on 2,4-xylenol, which is listed as a priority pollutant by the U.S. Environmental Protection Agency. Several enzymes involved in the oxidation of the para-methyl group, as well as the corresponding genes, have previously been reported. The enzyme catalyzing oxidation of the catabolic intermediate 4-hydroxyisophthalate to the ring cleavage substrate protocatechuate was also purified from strain NCIMB 9866, but its genetic determinant is still unavailable. In this study, the gene hipH, encoding 4-hydroxyisophthalate hydroxylase, from strain NCIMB 9866 was cloned by transposon mutagenesis. Purified recombinant HipH-His6 was found to be a dimer protein with a molecular mass of approximately 110 kDa. HipH-His6 catalyzed the hydroxylation of 4-hydroxyisophthalate to protocatechuate with a specific activity of 1.54 U mg−1 and showed apparent Km values of 11.40 ± 3.05 μM for 4-hydroxyisophthalate with NADPH and 11.23 ± 2.43 μM with NADH and similar Km values for NADPH and NADH (64.31 ± 13.16 and 72.76 ± 12.06 μM, respectively). The identity of protocatechuate generated from 4-hydroxyisophthalate hydroxylation by HipH-His6 has also been confirmed by high-performance liquid chromatography and mass spectrometry. Gene transcriptional analysis, gene knockout, and complementation indicated that hipH is essential for 2,4-xylenol catabolism but not for p-cresol catabolism in this strain. This fills a gap in our understanding of the gene that encodes a critical step in 2,4-xylenol catabolism and also provides another example of biochemical and genetic diversity of microbial catabolism of structurally similar compounds.

Nitrogen-source dependent regulation of manganese oxidation in Pseudomonas sp. AN-1: Mechanistic insights from multi-omics analyses

Aonan Qiao,Yu Liu,Fei Li,Haixia Pan,Yanan Guo,Yang Liu,Xianliang Yi,Hao Zhou

Manganese-oxidizing bacteria (MnOB) mediate the oxidation of Mn(II) in both natural and engineered environments. Although numerous MnOB have been isolated, the regulatory mechanisms governing their Mn(II)-oxidizing activity in response to nitrogen sources remain poorly understood. This study investigates how nitrogen sources affect the Mn(II)-oxidizing capability of Pseudomonas sp. AN-1. Mn(II) oxidation was completely inhibited in NH 4 + -supplemented cultures, with no detectable BioMnOx production throughout a 10-day incubation period. In contrast, complete oxidation of 100 μM Mn(II) occurred within 27 h when either NO 3 − or NO 2 − as the nitrogen source. Intriguingly, Mn(II) oxidation exhibited a histidine concentration-dependent pattern: no oxidation was observed at 0.5–1.0 mM histidine, whereas complete oxidation occurred at 2.5 mM. Transcriptomics and proteomics revealed NO 3 − -fed cultures exhibited significantly higher expression of manganese oxidation genes, including mnxG and mcoA , compared to histidine-supplemented cultures. Further analysis identified the MnxS/MnxR as essential for initiating the transcription of mnxG and mcoA . Bioinformatic analysis revealed this regulatory system is widely distributed in the genus Pseudomonas and frequently co-occurs with mnxG and mcoA . This study provides insight into nitrogen-source dependent regulation of bacterial Mn(II) oxidation, uncovering concentration-dependent effects and identifying the MnxS/MnxR system as a key regulatory node that integrates nitrogen sensing with Mn(II) oxidation.

Rapid Degradation of Hazardous Amides by Immobilized Engineered Pseudomonas putida KT2440 Based on a Novel Gene Expression Vector

Huoyong Jiang,Xuexiu Yu,Jingjing Guo,Guangdong Shang,Yijun Dai

The amides 4-trifluoromethylnicotinamide, acrylamide, and benzamide are widely used in agriculture and industry, posing hazards to the environment and animals. Immobilized bacteria are preferred in wastewater treatment, but degradation of these amides by immobilized engineered bacteria has not been explored. Here, engineered Pseudomonas putida KT2440 pLSJ15-amiA was constructed by introducing a new amidase gene expression vector into environmentally safe P. putida KT2440. P. putida KT2440 pLSJ15-amiA had high amidase activity, even at 80 °C. P. putida KT2440 pLSJ15-amiA immobilized with calcium alginate exhibited a greater environmental tolerance than free cells. The amides were rapidly degraded by the immobilized cells, but the activity was inhibited by high concentrations of substrates. The substrate inhibition model revealed that the optimum initial concentrations of 4-trifluoromethylnicotinamide, acrylamide, and benzamide for degradation by immobilized cells were 197.65, 350.76, and 249.40 μmol/L, respectively. This study develops a novel and excellent immobilized biocatalyst for remediation of wastewater containing hazardous amides.

Virtual screening of quorum sensing inhibitors against Pseudomonas tolaasii and its application in the preservation of mushroom (Agaricus bisporus)

Xinyu Luan,Yan Feng,Xiuxiu Chen,Yunrui Liu,Xiangbo Han,Yunfei Xie,Zhanli Liu

Pseudomonas tolaasii ( P. tolaasii ) is a main bacterial pathogen responsible for mushroom brown spot disease, and there is an urgent need for safer, more effective biocontrol solutions. The study focused on LuxI/R proteins, key quorum sensing (QS) regulators in P. tolaasii , by predicting their three-dimensional structures to screen potential quorum sensing inhibitors (QSIs). Thirteen kinds of natural plant essential oils (EOs) were identified as QSIs, and their QS activities were further determined. A thorough evaluation of the inhibitory effects of six kinds of EOs with QS activity on the QS phenotype of P. tolaasii was conducted, revealing that cinnamon essential oil (CEO) exhibited a substantial QS inhibitory effect on P. tolaasii . At 0.2 mg/mL, CEO significantly reduced bacterial motility, virulence factor secretion, and biofilm formation. Molecular docking and molecular dynamics simulations showed that cinnamaldehyde, the main bioactive compound in CEO, formed stable interactions with LuxI and LuxR proteins through van der Waals forces and electrostatic interactions. In simulated aqueous environments, the LuxI-cinnamaldehyde complex maintained its structural integrity over 25 ns, primarily due to the stabilizing effects of van der Waals forces and electrostatic interactions. In practical applications, CEO preservation pads effectively delayed mushroom spoilage and preserved postharvest quality. This research provides a reference for the screening and application of natural food QSIs.

The Effects of Baicalin in Combination with Cefotaxime on the Biofilm and Metabolic Reprogramming of Multidrug-Resistant Pseudomonas aeruginosa

Xin Meng,Chao Ning,Xinyu Lu,Mengna Kang,Yuxuan Yang,Zhiyun Yu,Yu Wang,Yantong Sun,Haiyong Guo

Baicalin, a natural plant-derived compound, holds promise in addressing clinical bacterial resistance when combined with antibiotics. This study evaluated the antibacterial activity of the combination of baicalin and cefotaxime and explored its mechanism of action on the cell wall and biofilm of multidrug-resistantPseudomonas aeruginosa(MRPA). The results showed that the combination of baicalin and cefotaxime exerted a synergistic inhibitory effect on the growth of MRPA, with a fractional inhibitory concentration index (FICI) of 0.28. Mechanistically, compared with cefotaxime alone, the combination of baicalin and cefotaxime enhanced the permeability of the cell membrane and cell wall of MRPA, thereby increasing cell damage. It also exhibited stronger antibiofilm activity by inhibiting numerous virulence factors (pyocyanin, elastase, lectin), reducing cellular metabolic activity, and downregulating the expression of biofilm genes (pslA,pelA,algD) and quorum-sensing genes (lasl,lasR,rhll,rhlR, pqsA, pqsR). The molecular docking results revealed that baicalin could stably bind to wbpE, LasR, and RhlR. Therefore, this interaction may indirectly influence the processes related to antibiotic resistance and biofilm formation in bacterial cells. Metabolomic analysis revealed that the combination of baicalin and cefotaxime upregulated 863 metabolites and downregulated 587 metabolites. These metabolites mainly included amino acids, lipids, nucleotides, carbohydrates, and secondary metabolites. The combination primarily enriched key pathways such as amino acid metabolism, lipid metabolism (sphingolipid metabolism) and secondary metabolite biosynthesis. Through these pathways, it triggers significant metabolic reprogramming, thereby interfering with the supply of cell wall synthesis precursors, membrane structural stability, and the generation of biomembrane matrix. Ultimately, it synergistically enhances the effects of cell wall damage and biomembrane inhibition. In conclusion, this study confirms that the combination of baicalin and cefotaxime exerts significant synergistic antibacterial activity against MRPA. It also reveals the mechanism of action of the combination on the cell wall and biofilm of MRPA at the metabolic level, providing theoretical support for the development of novel strategies to combat MRPA.

3-Hydroxy-pyridin-4(1H)-ones as siderophores mediated delivery of isobavachalcone enhances antibacterial activity against pathogenic Pseudomonas aeruginosa

Yong-Jun Huang,Xiao-Lin Zhong,Yi-Peng Zang,Ming-Han Yang,Jing Lin,Wei-Min Chen

The natural prenylated chalcone isobavachalcone ( IBC ) shows good antibacterial activity against Gram-positive bacteria but is ineffective against Gram-negative bacteria, most likely due to the outer membrane barrier of Gram-negative bacteria. The Trojan horse strategy has been shown to be an effective strategy to overcome the reduction in the permeability of the outer membrane of Gram-negative bacteria. In this study, eight different 3-hydroxy-pyridin-4(1 H )-one-isobavachalcone conjugates were designed and synthesized based on the siderophore Trojan horse strategy. The conjugates exhibited 8- to 32-fold lower minimum inhibitory concentrations (MICs) and 32- to 177-fold lower half-inhibitory concentrations (IC 50 s) against Pseudomonas aeruginosa PAO1 as well as clinical multidrug-resistant (MDR) strains compared to the parent IBC under iron limitation. Further studies showed that the antibacterial activity of the conjugates was regulated by the bacterial iron uptake pathway under different iron concentration conditions . Studies on the antibacterial mechanism of conjugate 1b showed that it exerts antibacterial activity by disrupting cytoplasmic membrane integrity and inhibiting cell metabolism. Finally, conjugate 1b showed a lower cytotoxic effects on Vero cells than IBC and a positive therapeutic effect in the treatment of bacterial infections caused by Gram-negative bacteria PAO1. Overall, this work demonstrates that IBC can be delivered to Gram-negative bacteria when combined with 3-hydroxy-pyridin-4(1H)-ones as siderophores and provides a scientific basis for the development of effective antibacterial agents against Gram-negative bacteria.

Selective and Sensitive Detection of Pseudomonas aeruginosa Based on Aminoguanidine-Functionalized Carbon Dots Synthesized by One-Step Hydrothermal Method

Liu Mei,Sun Zhaomeng,Guo Rong

Developing effective detection systems of pathogenic microbes is urgent to prevent human from bacterial infection. In this study, Pseudomonas aeruginosa ( P. aeruginosa ) as a model foodborne pathogen, we report a versatile strategy for construction of functionalized carbon dots-based sensors for detection of P. aeruginosa . The aminoguanidine-functionalized carbon dots (AG-CDs) with high biocompatibility and low toxicity were synthesized by a greener hydrothermal reaction between ascorbic acid and aminoguanidine. The AG-CDs exhibit good trapping ability toward P. aeruginosa due to the binding of the aminoguanidine residues to lipopolysaccharide (LPS) on P. aeruginosa . The fluorescence provided by AG-CDs/ P. aeruginosa conjugates is closely correlated with P. aeruginosa content. The linear detection range is 3–3 × 10 7  CFU/mL and the limit of detection is 1 CFU/mL. The fluorescence sensor exhibited successful practical applications of detecting P. aeruginosa in water and food. The finding provides the great potential of simple, inexpensive and efficient advantages in bacteria determination.

Efficient power recovery from aromatic compounds by a novel electroactive bacterium Pseudomonas putida B6-2 in microbial fuel cells

Xiaoyan Qi,Huimin Wang,Xinyu Gao,Lei Zhang,Sen wang,Xia Wang,Ping Xu

Environmental pollution caused by aromatic compounds (ACs) has long stimulated the emergence of creative bioremediation strategies. Pseudomonas putida B6–2, an aerobic ACs degrading bacterium, successfully coupled ACs degradation with power generation in microbial fuel cells (MFCs) when a nickel-coated sponge with a three-dimensional macroporous structure served as the anode. The simultaneous removal of coexisting ACs pollutants including biphenyl (BP), carbazole (CA), and dibenzothiophene (DBT) were achieved in MFCs, accompanied by the efficient power densities of 469 mW m −2 , 499 mW m −2 , 541 mW m −2 , and 587 mW m −2 for single (BP), binary (BP+DBT or BP+CA), and ternary (BP+DBT+CA) ACs fueled MFCs, respectively. Degradation dynamics analysis indicated that the degradation of BP, CA, and DBT was consistent with the pseudo-first order kinetic model in the ternary ACs fueled MFC, and BP had a higher degradation rate ( k obs =0.0337 h –1 ) than DBT ( k obs =0.0201 h –1 ) and CA ( k obs =0.0149 h –1 ). It is the first time that P. putida B6–2 was discovered as an electroactive bacterium with high extracellular electron transfer (EET) capability. The EET preliminary analysis showed that P. putida B6–2 might transfer extracellular electrons by redox mediators and microbial nanowires . The mediators may play a key role in indirect EET at the start-up period of the MFCs, while the nanowires may involve in direct EET during the whole discharge process of the MFCs. The interesting findings may lay a foundation for further exploration of the EET of P. putida B6–2 and bioremediation of ACs pollutants.

Biomolecular insights into the inhibition of heavy metals on reductive dechlorination of 2,4,6-trichlorophenol in Pseudomonas sp. CP-1

Di Cao,Xueqi Chen,Jun Nan,Aijie Wang,Zhiling Li

Influences of heavy metal exposure to the organohalide respiration process and the related molecular mechanism remain poorly understood. In this study, a non-obligate organohalide respiring bacterium, Pseudomonas sp. strain CP-1, was isolated and its molecular response to the five types of commonly existed heavy metal ions were thoroughly investigated. All types of heavy metal ions posed inhibitory effects on 2,4,6-trichlorophenol dechlorination activity and cell growth with the varied degree. Exposure to Cu (II) showed the most serious inhibitive effects on dechlorination even at the lowest concentration of 0.05 mg/L, while the inhibition by As (V) was the least with the removal kinetic constant k decreased to 0.05 under 50 mg/L. Further, multi-omics analysis found compared with Cu (II), As (V) exposure led to the insignificant downregulation of a variety of biosynthesis processes, which would be one possible account for the less inhibited activity. More importantly, the inhibited mechanisms on the organohalide respiration catabolism of strain CP-1 were firstly revealed. Cu (II) stress severely downregulated NADH generation during TCA cycle and electron donation of organohalide respiration process, which might decrease the reducing power required for organohalide respiration. While both Cu (II) and As (Ⅴ) inhibited substrate level phosphorylation during TCA cycle, as well as electron transfer and ATP generation during organohalide respiration. Meanwhile, CprA-2 was confirmed as the responsible reductive dehalogenase in charge of 2,4,6-TCP dechlorination, and transcriptional and proteomic studies confirmed the directly inhibited gene transcription and expression of CprA-2. The in-depth reveal of inhibitory effects and mechanism gave theoretical supports for alleviating heavy metal inhibition on organohalide respiration activity in groundwater co-contaminated with organohalides and heavy metals.

Alkaline phosphatase LapA regulates quorum sensing–mediated virulence and biofilm formation in Pseudomonas aeruginosa PAO1 under phosphate depletion stress

Xiaojuan Tan,Xi Cheng,Jingjing Xiao,Qianqian Liu,Dongsheng Du,Minghui Li,Yang Sun,Jinwei Zhou,Guoping Zhu

Selective Biosynthesis of Furoic Acid From Furfural by Pseudomonas Putida and Identification of Molybdate Transporter Involvement in Furfural Oxidation

Zheng Zhaojuan,Xu Qianqian,Tan Huanghong,Zhou Feng,Ouyang Jia

Upgrading of furanic aldehydes to their corresponding furancarboxylic acids has received considerable interest recently. Herein we reported selective oxidation of furfural (FAL) to furoic acid (FA) with quantitative yield using whole-cells of Pseudomonas putida KT2440. The biocatalytic capacity could be substantially promoted through adding 5-hydroxymethylfurfural into media at the middle exponential growth phase. The reaction pH and cell dosage had notable impacts on both FA titer and selectivity. Based on the validation of key factors for FAL conversion, the capacity of P. putida KT2440 to produce FAL was substantially improved. In batch bioconversion, 170 mM FA was produced with selectivity nearly 100% in 2 h, whereas 204 mM FA was produced with selectivity above 97% in 3 h in fed-batch bioconversion. Particularly, the role of molybdate transporter in oxidation of FAL and 5-hydroxymethylfurfural was demonstrated for the first time. The furancarboxylic acids synthesis was repressed markedly by destroying molybdate transporter, which implied Mo-dependent enzyme/molybdoenzyme played pivotal role in such oxidation reactions. This research further highlights the potential of P. putida KT2440 as next generation industrial workhorse and provides a novel understanding of molybdoenzyme in oxidation of furanic aldehydes.