APPLIED AND ENVIRONMENTAL MICROBIOLOGY
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2022
·Vol. 88
·期 4
·
IF 5.005
Zhijian Ke,Qian Zhu,Siyuan Gao,Mingliang Zhang,Mingli Jiang,Yijun Ren,Yali Liu,Yidong Zhou,Jiguo Qiu,Qing Hong
Previously, a LysR family transcriptional regulator, McbG, that activates the mcbBCDEF gene cluster involved in the upstream pathway (from carbaryl to salicylate) of carbaryl degradation in Pseudomonas sp. strain XWY-1 was identified by us (Z. Ke, Y. Zhou, W. Jiang, M. Zhang, et al., Appl Environ Microbiol 87:e02970-20, 2021, https://doi.org/10.1128/AEM.02970-20). In this study, we identified McbH and McbN, which activate the mcbIJKLM cluster (responsible for the midstream pathway, from salicylate to gentisate) and the mcbOPQ cluster (responsible for the downstream pathway, from gentisate to pyruvate and fumarate), respectively. They both belong to the LysR family of transcriptional regulators. Gene disruption and complementation study reveal that McbH is essential for transcription of the mcbIJKLM cluster in response to salicylate and McbN is indispensable for the transcription of the mcbOPQ cluster in response to gentisate. The results of electrophoretic mobility shift assay (EMSA) and DNase I footprinting showed that McbH binds to the 52-bp motif in the mcbIJKLM promoter area and McbN binds to the 58-bp motif in the mcbOPQ promoter area. The key sequence of McbH binding to the mcbIJKLM promoter is a 13-bp motif that conforms to the typical characteristics of the LysR family. However, the 12-bp motif that is different from the typical characteristics of the LysR family regulator binding site sequence is identified as the key sequence for McbN to bind to the mcbOPQ promoter. This study revealed the regulatory mechanisms for the midstream and downstream pathways of carbaryl degradation in strain XWY-1 and further our knowledge of (and the size of) the LysR transcription regulator family.IMPORTANCE The enzyme-encoding genes involved in the complete degradation pathway of carbaryl in Pseudomonas sp. strain XWY-1 include mcbABCDEF, mcbIJKLM, and mcbOPQ. Previous studies demonstrated that the mcbA gene, responsible for hydrolysis of carbaryl to 1-naphthol, is constitutively expressed and that the transcription of mcbBCDEF was regulated by McbG. However, the transcription regulation mechanisms of mcbIJKLM and mcbOPQ have not been investigated yet. In this study, we identified two LysR-type transcriptional regulators, McbH and McbN, which activate the mcbIJKLM cluster (responsible for the degradation of salicylate to gentisate) and the mcbOPQ cluster (responsible for the degradation of gentisate to pyruvate and fumarate), respectively. The 13-bp motif is critical for McbH to bind to the promoter of mcbIJKLM, and 12-bp motif different from the typical characteristics of the LysR-type transcriptional regulator (LTTR) binding sequence affects the binding of McbN to the promoter. These findings help to expand the understanding of the regulatory mechanism of microbial degradation of carbaryl.
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高影响因子
Frontiers in Microbiology
·
2020
·
IF 4.236
Wang Xin-Yun,Xie Jing
Food spoilage by certain species of bacteria is reported to be regulated by quorum sensing (QS). Acinetobacter johnsonii and Pseudomonas fluorescens, the major specific spoilage organisms, are found to be limited in their QS and co-culture interactions. The aim of this study was to determine how QS-regulated proteins affect the spoilage potential of co-cultured A. johnsonii and P. fluorescens obtained from spoiled bigeye tuna (Thunnus obesus) using a proteomics approach. The A. johnsonii, P. fluorescens, and their co-culture tested the N-acyl-homoserine lactone (AHL) activities using reporter Chromobacterium violaceum CV026 and LC-MS/MS in qualitative and quantitative approaches, respectively. These latter showed that, of the 470 proteins and 444 proteins in A. johnsonii (A) and P. fluorescens (P), respectively, 80 were significantly up-regulated and 97 were significantly down-regulated in A vs. AP, whereas 90 were up-regulated and 65 were down-regulated in P vs. AP. The differentially expressed proteins included the AI-2E family transporter OS, 50S ribosomal protein L3, thioredoxin reductase OS, cysteine synthase CysM OS, DNA-binding response regulator, and amino acid ABC transporter ATPase OS. The cellular process (GO:0009987), metabolic process (GO:0008152), and single-organism process (GO:0044699) were classified into the gene ontology (GO) term. In addition, energy production and conversion, amino acid transport and metabolism, translation, ribosomal structure and biogenesis, post-translational modification, protein turnover, and chaperones were distributed into the clusters of orthologous groups of proteins (COG) terms. The KEGG pathways revealed that 84 and 77 differentially expressed proteins were divided into 20 KEGG pathways in A vs. AP and P vs. AP, respectively, and amino acid metabolism, carbohydrate metabolism, energy metabolism, and translation were significantly enriched. Proteins that correlated with the spoilage-related metabolic pathways, including thioredoxin reductase OS, cysteine synthase OS, and pyridoxal phosphate-dependent enzyme family protein OS, were identified. AI-2E family transporter OS and LuxR family transcriptional regulator OS were identified that related to the QS system. These findings provide a differential proteomic profile of co-culture in A. johnsonii and P. fluorescens, and have potential applications in QS and the regulation of spoilage potential.
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BIOTECHNOLOGY & BIOTECHNOLOGICAL EQUIPMENT
·
2021
·
IF 1.632
Bo Wang,Feng Gao,Jing Xu,Jianjie Gao,Zhenjun Li,Lijuan Wang,Fujian Zhang,Yu Wang,Yongsheng Tian,Rihe Peng,Quanhong Yao
Biological treatment is a cost-effective and environmentally friendly technique for treating toluene. However, this process is limited by the type and quantity of toluene degraders that can be applied to different environments and methods. It is a feasible solution to constructing new genetic engineering organisms for toluene degradation through biotechnology. To facilitate genetic manipulation and improve gene expression, the toluene/o-xylene monooxygenase locus from Pseudomonas stutzeri was reconstructed and artificially synthesized. All six genes were optimized and driven with a monocistronic transcriptional pattern by T7 promoter and terminator to be expressed at a high level. The engineered bacteria can hydroxylate toluene to a mixture of o-, m- and p-cresol, which are then further oxidized to 3- and 4-methylcatechol. Benzene can also be oxidized to phenol, catechol and pyrogallol successively. The negative effects of toluene can be removed by the engineered bacteria via proteomics analysis. Overall, the artificial gene clusters established in this study can be used to construct different toluene and benzene degradation organisms for bioremediation.Supplemental data for this article is available online at https://doi.org/10.1080/13102818.2021.1996267 .
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SCIENCE OF THE TOTAL ENVIRONMENT
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2020
·
IF 6.551
Yuan Li,Yu Yang,Yuruo Feng,Jian Pu,Li-an Hou
Biofouling caused by the growth of the biofilm is the main bottleneck that limits the effective operation of thin-film composite (TFC) membrane in the forward osmosis (FO) process. This study investigated the combined effects of graphene oxide (GO) immobilized thin-film nanocomposite (TFN-S) membrane and Pseudomonas quinolone signal (PQS)-based quorum quenching on biofouling mitigation, especially under the operation of pressure-retarded osmosis (PRO) mode, and the influence of methyl anthranilate (MA) inhibitor on the composition and structure of biofilm was also evaluated. Synthetic wastewater was used as the feed solution, in which the model strain Pseudomonas aeruginosa was added to simulate biofouling. The results showed that GO modification and MA addition both efficiently mitigated flux decline and EPS secretion, but the interference of PQS pathway on biofouling control was better than GO embedding. TFN-S membrane with MA addition exhibited superior anti-biofouling performance based on the combined effects of GO and MA. The alleviated concentration polarization and enhanced hydrophilicity of the TFN-S membrane reduced the flux decline in the early stage. Additionally, the antibacterial property of GO inhibited the viability of the attached bacteria (under PRO mode) and MA further mitigated the EPS secretion and biofilm development in the later stage. In the presence of PQS inhibitor MA, live/total cells ratio was 15% and 13% higher than that of TFC membrane in FO and PRO modes, respectively. Furthermore, exogenous addition of MA led to a relatively loose biofilm structure, resulting in high membrane permeability in the biofouling formation process.
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Bioresources and Bioprocessing
·
2018
·Vol. 5
·期 1
·1-11
·
IF 0
Liu Xin,Wang Weiwei,Hu Haiyang,Lu Xinyu,Zhang Lige,Xu Ping,Tang Hongzhi
Background Benzofuran and its derivatives contain central pharmacophores and are important structures in medicinal chemistry. Chemical synthesis of benzofuran rings often requires expensive catalysts and stringent operational conditions. Biosynthesis is recognized as a promising way to save energy and produce valuable compounds. Dioxin biodegradation pathways can form several benzofuran derivatives, and these pathways may be a better choice for further synthesis of important biological compounds. 2-Hydroxy-4-(3′-oxo-3′ H -benzofuran-2′-yliden)but-2-enoic acid (HOBB), a benzofuran derivative, can be biosynthesized from dibenzofuran (DBF) through co-metabolic degradation in a lateral dioxygenation pathway. Results Efficient biosynthesis of HOBB was observed using whole cells of Pseudomonas putida strain B6-2. After cultivation in LB medium containing biphenyl, the cells were suspended to an OD 600 of 5 to conduct biosynthesis in the presence of 0.5-mM DBF at pH 7 for 8 h. The bacterial cells were used twice to degrade approximately 0.70-mM DBF, and in batch process, accumulated about 0.29-mM HOBB. HOBB could be easily purified from the reaction with ethyl acetate using the neutral-acid extraction method, and 13.58 ± 0.31 mg of HOBB was obtained from 22.49 ± 0.74-mg DBF with an overall production yield of 60.4% (w/w). The product HOBB, which is a yellow powder, could be detected and identified by LC–MS, GC–MS, and NMR. Conclusions In this study, a new biological route was developed to produce HOBB from DBF using whole cells of P. putida B6-2 (DSM 28064). The biosynthesis of HOBB may contribute to studies of the DBF lateral pathway and provide a new green route for synthesizing benzofuran derivatives with pharmacological activities.
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FOOD CONTROL
·
2018
·
IF 3.667
Xinran Lv,Huanhuan Ma,Mengtong Sun,Yang Lin,Fengling Bai,Jianrong Li,Bolin Zhang
A novel bacteriocin DY4-2 was produced by strain DY4-2 which was isolated from cutlassfish ( Trichiurus lepturus ) and identified as Lactobacillus plantarum . This bacteriocin reached the maximum production at stationary phase after 24 h incubation. It was purified by ethyl acetate extraction followed by ultrafiltration, Sephadex G25 chromatography and high-performance liquid chromatography. The molecular mass of bacteriocin DY4-2 was determined as 1465 Da by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis. The amino acid sequence of bacteriocin DY4-2 was predicted to be HAQIGMTMNGSFR by MALDI-TOF-MS/MS. Bacteriocin DY4-2 was heat-stable (30 min at 121 °C) and kept active at the pH range of 2.5–5.5, but was sensitive to proteolytic enzymes. The mode of action of bacteriocin DY4-2 was bactericidal. It exhibited broad spectrum antimicrobial activity against fish pathogenic and spoilage bacteria, such as Pseudomonas fluorescens , P. aeruginosa , Vibrio parahaemolyticus , Aeromonas sobria and Listeria monocytogenes . The addition of partially purified bacteriocin DY4-2 in turbot fillets reduced the number of P. fluorescens by 2.7 log units at 4 °C storage for 12 days. Moreover, compared to the control, a significant decline in total viable counts and total volatile base nitrogen was observed in bacteriocin DY4-2 treated samples. Theses results suggested that bacteriocin DY4-2 had potential to act as seafood bio-preservative.
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Fermentation-Basel
·
2021
·Vol. 7
·期 4
·309
·
IF 3.975
Yiming Sun,Xiaowei Lin,Shaodong Zhu,Jianmeng Chen,Yi He,Yao Shi,Hua Liu,Lei Qin
The biotrickling filter (BTF) treatment is an effective way of dealing with air pollution caused by volatile organic compounds (VOCs). However, this approach is typically used for single VOCs treatment but not for the mixtures of VOC and volatile organic sulfur compounds (VOSCs), even if they are often encountered in industrial applications. Therefore, we investigated the performance of BTF for single and ternary mixture gas of dimethyl sulfide (DMS), propanethiol, and toluene, respectively. Results showed that the co-treatment enhanced the removal efficiency of toluene, but not of dimethyl sulfide or propanethiol. Maximum removal rates (rmax) of DMS, propanethiol and toluene were calculated to be 256.41 g·m−3·h−1, 204.08 g·m−3·h−1and 90.91 g·m−3·h−1, respectively. For a gas mixture of these three constituents,rmaxwas measured to be 114.94 g·m−3·h−1, 104.17 g·m−3·h−1and 99.01 g·m−3·h−1, separately. Illumina MiSeq sequencing analysis further indicated that Proteobacteria and Bacteroidetes were the major bacterial groups in BTF packing materials. A shift of bacterial community structure was observed during the biodegradation process.Keywords:biotrickling filter;decomposition;dimethyl sulfide;pollution;propanethiol;toluene
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Materials Today Bio
·
2025
·
IF 10.2
Shuangying Yang,Youjia Wu,Xiaoyuan Huang,Xiaoyu Li,Yao Wang,Jianfeng Pan,Zhengjun Huang,Shaohuang Weng,Jianyong Huang
The treatment of infectious wounds is confronted with the challenges of antibiotic-resistant bacterial infections and excessive inflammatory responses, significantly impacting the healing process. A multifunctional hydrogel dressing system used as local strategy is needed to address this clinical dilemma. Herein, a kind of carbon dots (P-CDs) were synthesized using polyhexamethylene guanidine (PHMG) and citric acid (CA) through a hydrothermal method, exhibiting excellent broad-spectrum antibacterial activity, including effective inhibition of clinically isolated resistant bacteria. The antibacterial mechanism of P-CDs involved the generation of reactive oxygen species, inhibition of ATP synthesis, and disruption of bacterial membrane integrity with the leakage of protein. Additionally, P-CDs demonstrate pronounced immunomodulatory properties by inducing macrophage polarization toward the M2 phenotype, thus modulating the inflammatory microenvironment. These functional components were incorporated into an intelligent hydrogel system (P-CDs@EPCS) constructed from ε-poly-L-lysine and carboxymethyl chitosan, resulting in a wound dressing with tissue adhesion, resilient maintenance of mechanical integrity, and favorable mechanical properties. P-CDs@EPCS exhibited a sustained pH-responsive drug release profile for up to 10 days, maintaining the stability of active constituents throughout the release period. In vivo experiments confirmed that P-CDs@EPCS significantly accelerated wound healing in infections caused by Pseudomonas aeruginosa , demonstrating a synergistic effect of antibacterial, anti-inflammatory, and repair-promoting actions. This study provides a promising solution for treating infectious wounds, integrating key advancements in the field of hydrogels, including dynamic crosslinking design and smart drug delivery systems.
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