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Stoodley P, Toelke N, Schwermer C, de Beer D. Bioenergetics of simultaneous oxygen and nitrate respiration and nitric oxide production in a Pseudomonas aeruginosa agar colony biofilm. Biofilm 2024; 7:100181. [PMID: 38425549 PMCID: PMC10902143 DOI: 10.1016/j.bioflm.2024.100181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 01/09/2024] [Accepted: 02/01/2024] [Indexed: 03/02/2024] Open
Abstract
Pseudomonas aeruginosa is a biofilm forming pathogen commonly associated with infection of the cystic fibrosis (CF) lung, chronic wounds and indwelling medical devices. P. aeruginosa is a facultative aerobe that can use nitrate (NO3-) found in healthy and infected tissues and body fluids to generate energy through denitrification. Further, P. aeruginosa the expression of denitrification genes has been found in specimens from people with CF. The main aim of this study was to determine the relative energy contribution of oxygen (O2) respiration and denitrification in single Pseudomonas aeruginosa PAO1 biofilm colonies under different O2 concentrations to estimate the possible relative importance of these metabolic processes in the context of biofilm infections. We showed that the used strain PAO1 in biofilms denitrified with nitrous oxide (N2O), and not nitrogen (N2), as the end product in our incubations. From simultaneous O2 and N2O microprofiles measured with high spatial resolution by microsensors in agar colony biofilms under air, N2 and pure O2, the rates of aerobic respiration and denitrification were calculated and converted to ATP production rates. Denitrification occurred both in the oxic and anoxic zones, and became increasingly dominant with decreasing O2 concentrations. At O2 concentrations characteristic for tissues and wounds (20-60 μM), denitrification was responsible for 50% of the total energy conservation in the biofilm. In addition the formation of nitric oxide (NO), a precursor of N2O and an important regulator of many cellular processes, was strongly influenced by the local O2 concentrations. NO production was inhibited under pure O2, present under anoxia (∼1 μM) and remarkably high (up to 6 μM) under intermediate O2 levels, which can be found in infected tissues. Possible impacts of such NO levels on both the host and the biofilm bacteria are discussed.
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Affiliation(s)
- Paul Stoodley
- National Centre for Advanced Tribology at Southampton, (NCATS), Mechanical Engineering, University of Southampton, Southampton, SO17 1BJ, UK
- Department of Microbial Infection and Immunity, Department of Orthopaedics, The Ohio State University, 716 Biomedical Research Tower (BRT), 460 W 12th Ave, Columbus OH, 43210, United States
| | - Nina Toelke
- Max Planck Institute for Marine Microbiology (MPI), Microsensor Group and Molecular Ecology Group, Celsiusstrasse 1, D-28359, Bremen, Germany
| | - Carsten Schwermer
- Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349, Oslo, Norway
| | - Dirk de Beer
- Max Planck Institute for Marine Microbiology (MPI), Microsensor Group and Molecular Ecology Group, Celsiusstrasse 1, D-28359, Bremen, Germany
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Tan X, Hu M, Cheng X, Xiao J, Zhou J, Zhu G. Effects of elevated levels of intracellular nitric oxide on Pseudomonas aeruginosa biofilm in chronic skin wound and slow-killing infection models. Int Microbiol 2024; 27:349-359. [PMID: 37410300 DOI: 10.1007/s10123-023-00395-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 06/19/2023] [Accepted: 06/29/2023] [Indexed: 07/07/2023]
Abstract
Nitric oxide (NO), produced through the denitrification pathway, regulates biofilm dynamics through the quorum sensing system in Pseudomonas aeruginosa. NO stimulates P. aeruginosa biofilm dispersal by enhancing phosphodiesterase activity to decrease cyclic di-GMP levels. In a chronic skin wound model containing a mature biofilm, the gene expression of nirS, encoding nitrite reductase to produce NO, was low, leading to reduced intracellular NO levels. Although low-dose NO induces biofilm dispersion, it is unknown whether it influences the formation of P. aeruginosa biofilms in chronic skin wounds. In this study, a P. aeruginosa PAO1 strain with overexpressed nirS was established to investigate NO effects on P. aeruginosa biofilm formation in an ex vivo chronic skin wound model and unravel the underlying molecular mechanisms. Elevated intracellular NO levels altered the biofilm structure in the wound model by inhibiting the expression of quorum sensing-related genes, which was different from an in vitro model. In Caenorhabditis elegans as a slow-killing infection model, elevated intracellular NO levels increased worms' lifespan by 18%. Worms that fed on the nirS-overexpressed PAO1 strain for 4 h had complete tissue, whereas worms that fed on empty plasmid-containing PAO1 had biofilms on their body, causing severe damage to the head and tail. Thus, elevated intracellular NO levels can inhibit P. aeruginosa biofilm growth in chronic skin wounds and reduce pathogenicity to the host. Targeting NO is a potential approach to control biofilm growth in chronic skin wounds wherein P. aeruginosa biofilms are a persistent problem.
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Affiliation(s)
- Xiaojuan Tan
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, Anhui, China.
| | - Mei Hu
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, Anhui, China
| | - Xi Cheng
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, Anhui, China
| | - Jingjing Xiao
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, Anhui, China
| | - Jinwei Zhou
- School of Food and Biology Engineering, Xuzhou University of Technology, Xuzhou, 221018, Jiangsu, China.
| | - Guoping Zhu
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, Anhui, China.
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Luo K, Chen L, Zhao Y, Peng G, Chen Z, Chen Q. Transcriptomics uncover the response of an aerobic denitrifying bacteria to zinc oxide nanoparticles exposure. ENVIRONMENTAL TECHNOLOGY 2023; 44:3685-3697. [PMID: 35466863 DOI: 10.1080/09593330.2022.2069517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 04/08/2022] [Indexed: 06/14/2023]
Abstract
Zinc oxide nanoparticles (ZnO NPs) show adverse impacts on aerobic denitrifying bacteria, little is known about the response of these bacteria to ZnO NPs exposure at cellular level. This study assessed the multiple responses of Pseudomonas aeruginosa PCN-2 under ZnO NPs exposure. We demonstrated that ZnO NPs exposure could inhibit the intracellular metabolism and stimulate the antioxidant defence capability of PCN-2. At lower exposure concentration (5 mg/L), exogenous ROS generated and resulted in the inhibition of pyruvate metabolism and citrate cycle, which caused deficient energy for aerobic denitrification. At higher concentrations (50 mg/L), endogenous ROS additionally generated and triggered to stronger down-regulation of oxidative phosphorylation, which caused suppressed electron transfers for aerobic denitrification. Meanwhile, ZnO NPs exposure promoted EPS production and biofilm formation, and antioxidases was especially particularly stimulated at higher concentration. Our findings are significant for understanding of microbial bacterial susceptibility, tolerance and resistance under the exposure of ZnO NPs.
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Affiliation(s)
- Kongyan Luo
- College of Environmental Sciences and Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, PR People's Republic of China
- State Environmental Protection Key Laboratory of All Materials Flux in River Ecosystems, Beijing, People's Republic of China
- College of Environment and Resources, Dalian Minzu University, Dalian, PR People's Republic of China
| | - Long Chen
- College of Environmental Sciences and Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, PR People's Republic of China
- State Environmental Protection Key Laboratory of All Materials Flux in River Ecosystems, Beijing, People's Republic of China
| | - Yuanyi Zhao
- College of Environmental Sciences and Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, PR People's Republic of China
- State Environmental Protection Key Laboratory of All Materials Flux in River Ecosystems, Beijing, People's Republic of China
| | - Guyu Peng
- College of Environmental Sciences and Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, PR People's Republic of China
- State Environmental Protection Key Laboratory of All Materials Flux in River Ecosystems, Beijing, People's Republic of China
| | - Zhaobo Chen
- College of Environment and Resources, Dalian Minzu University, Dalian, PR People's Republic of China
| | - Qian Chen
- College of Environmental Sciences and Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, PR People's Republic of China
- State Environmental Protection Key Laboratory of All Materials Flux in River Ecosystems, Beijing, People's Republic of China
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Efremenko E, Senko O, Stepanov N, Aslanli A, Maslova O, Lyagin I. Quorum Sensing as a Trigger That Improves Characteristics of Microbial Biocatalysts. Microorganisms 2023; 11:1395. [PMID: 37374897 DOI: 10.3390/microorganisms11061395] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 05/22/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
Quorum sensing (QS) of various microorganisms (bacteria, fungi, microalgae) today attracts the attention of researchers mainly from the point of view of clarifying the biochemical basics of this general biological phenomenon, establishing chemical compounds that regulate it, and studying the mechanisms of its realization. Such information is primarily aimed at its use in solving environmental problems and the development of effective antimicrobial agents. This review is oriented on other aspects of the application of such knowledge; in particular, it discusses the role of QS in the elaboration of various prospective biocatalytic systems for different biotechnological processes carried out under aerobic and anaerobic conditions (synthesis of enzymes, polysaccharides, organic acids, etc.). Particular attention is paid to the biotechnological aspects of QS application and the use of biocatalysts, which have a heterogeneous microbial composition. The priorities of how to trigger a quorum response in immobilized cells to maintain their long-term productive and stable metabolic functioning are also discussed. There are several approaches that can be realized: increase in cell concentration, introduction of inductors for synthesis of QS-molecules, addition of QS-molecules, and provoking competition between the participants of heterogeneous biocatalysts, etc.).
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Affiliation(s)
- Elena Efremenko
- Faculty of Chemistry, Lomonosov Moscow State University, Lenin Hills 1/3, 119991 Moscow, Russia
| | - Olga Senko
- Faculty of Chemistry, Lomonosov Moscow State University, Lenin Hills 1/3, 119991 Moscow, Russia
| | - Nikolay Stepanov
- Faculty of Chemistry, Lomonosov Moscow State University, Lenin Hills 1/3, 119991 Moscow, Russia
| | - Aysel Aslanli
- Faculty of Chemistry, Lomonosov Moscow State University, Lenin Hills 1/3, 119991 Moscow, Russia
| | - Olga Maslova
- Faculty of Chemistry, Lomonosov Moscow State University, Lenin Hills 1/3, 119991 Moscow, Russia
| | - Ilya Lyagin
- Faculty of Chemistry, Lomonosov Moscow State University, Lenin Hills 1/3, 119991 Moscow, Russia
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Chen XT, Zhao BH, Zhang J, Li YQ, Yang HS, Zhang YQ. Rapid start-up of partial nitrification reactor by exogenous AHLs and Vanillin combined with intermittent aeration. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 859:160191. [PMID: 36395855 DOI: 10.1016/j.scitotenv.2022.160191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 11/10/2022] [Accepted: 11/10/2022] [Indexed: 06/16/2023]
Abstract
Quorum sensing (QS) and quorum quenching (QQ) are common phenomena in microbial systems and play an important role in the nitrification process. However, rapidly start up partial nitrification regulated by N-acyl-homoserine lactones (AHLs)-mediated QS or QQ has not been reported. Hence, we chose N-butyryl homoserine lactone (C4-HSL) and N-hexanoyl homoserine lactone (C6-HSL) as the representative AHLs, and Vanillin as the representative quorum sensing inhibitor (QSI) combined intermittent aeration to investigate their effects on the start-up process of partial nitrification. The start-up speed in the group with C4-HSL or C6-HSL addition was 1.42 or 1.26 times faster than that without addition, respectively. Meanwhile, the ammonium removal efficiency with C4-HSL or C6-HSL addition was increased by 13.87 % and 17.30 % than that of the control group, respectively. And, partial nitrification could maintain for a certain period without AHLs further addition. The increase of Nitrosomonas abundance and ammonia monooxygenase (AMO) activity, and the decrease of Nitrobacter abundance and nitrite oxidoreductase (NXR) activity were the reasons for the rapid start-up of partial nitrification in the AHLs groups. Vanillin addition reduced AMO and hydroxylamine oxidoreductase (HAO) activity, and increased Nitrobacter abundance and NXR activity, thus these were not conducive to achieving partial nitrification. Denitrifying bacteria (Hydrogenophaga, Thauera and Aquimonas) abundance increased in the Vanillin group. QS-related bacteria and gene abundance were elevated in the AHLs group, and reduced in the Vanillin group. Function prediction demonstrated that AHLs promoted the nitrogen cycle while Vanillin enhanced the carbon cycle. This exploration might provide a new technical insight into the rapid start-up of partial nitrification based on QS control.
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Affiliation(s)
- Xiao-Tang Chen
- Department of Municipal Engineering, Beijing University of Technology, Beijing 100124, PR China
| | - Bai-Hang Zhao
- Department of Municipal Engineering, Beijing University of Technology, Beijing 100124, PR China.
| | - Jing Zhang
- Department of Municipal Engineering, Beijing University of Technology, Beijing 100124, PR China
| | - Yu-Qi Li
- Department of Municipal Engineering, Beijing University of Technology, Beijing 100124, PR China
| | - Hai-Shan Yang
- Department of Municipal Engineering, Beijing University of Technology, Beijing 100124, PR China
| | - Yu-Qing Zhang
- Department of Municipal Engineering, Beijing University of Technology, Beijing 100124, PR China
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Effects of ginkgolic acid(C15:1)on biofilm formation, pathogenic factor production and quorum sensing of Pseudomonas aeruginosa. Microb Pathog 2022; 173:105813. [DOI: 10.1016/j.micpath.2022.105813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 09/16/2022] [Accepted: 09/28/2022] [Indexed: 11/06/2022]
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Molecular Mechanisms and Applications of N-Acyl Homoserine Lactone-Mediated Quorum Sensing in Bacteria. Molecules 2022; 27:molecules27217584. [PMID: 36364411 PMCID: PMC9654057 DOI: 10.3390/molecules27217584] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 11/02/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
Microbial biodiversity includes biotic and abiotic components that support all life forms by adapting to environmental conditions. Climate change, pollution, human activity, and natural calamities affect microbial biodiversity. Microbes have diverse growth conditions, physiology, and metabolism. Bacteria use signaling systems such as quorum sensing (QS) to regulate cellular interactions via small chemical signaling molecules which also help with adaptation under undesirable survival conditions. Proteobacteria use acyl-homoserine lactone (AHL) molecules as autoinducers to sense population density and modulate gene expression. The LuxI-type enzymes synthesize AHL molecules, while the LuxR-type proteins (AHL transcriptional regulators) bind to AHLs to regulate QS-dependent gene expression. Diverse AHLs have been identified, and the diversity extends to AHL synthases and AHL receptors. This review comprehensively explains the molecular diversity of AHL signaling components of Pseudomonas aeruginosa, Chromobacterium violaceum, Agrobacterium tumefaciens, and Escherichia coli. The regulatory mechanism of AHL signaling is also highlighted in this review, which adds to the current understanding of AHL signaling in Gram-negative bacteria. We summarize molecular diversity among well-studied QS systems and recent advances in the role of QS proteins in bacterial cellular signaling pathways. This review describes AHL-dependent QS details in bacteria that can be employed to understand their features, improve environmental adaptation, and develop broad biomolecule-based biotechnological applications.
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TMT-based proteomic analysis of the inactivation effect of high voltage atmospheric cold plasma treatment on Pseudomonas aeruginosa. Lebensm Wiss Technol 2022. [DOI: 10.1016/j.lwt.2022.113981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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AHL-mediated quorum sensing to regulate bacterial substance and energy metabolism: A review. Microbiol Res 2022; 262:127102. [DOI: 10.1016/j.micres.2022.127102] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 06/08/2022] [Accepted: 06/22/2022] [Indexed: 01/09/2023]
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Hu J, Wang J, Li J, Hu H, Wu B, Ren H, Wang J. AHLS-pred: a novel sequence-based predictor of acyl-homoserine-lactone synthases using machine learning algorithms. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:616-631. [PMID: 35403334 DOI: 10.1111/1758-2229.13068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 03/28/2022] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
Acyl-homoserine-lactones (AHLs), as the major quorum sensing (QS) signalling molecules in Gram-negative bacteria, have shown great application potential in regulating biological nutrient removal process. The identification of AHLs synthases plays an essential role in in-depth research on QS mechanisms and applications of biological wastewater treatment processes. This work proposed the first prediction model for AHLs synthases based on machine learning algorithms, namely, AHLS-pred. The training dataset AHLS1400 and the independent testing dataset AHLS132 for AHLSs prediction were first established. Three sequence-based feature extraction methods are utilized to generate feature descriptors, namely, amino acid composition, dipeptide composition and G-gap dipeptide composition respectively. Subsequently, the optimal features were obtained based on the sorted feature descriptors (in F-score order) and the sequential forward search strategy. By comparing five different machine learning algorithms, the final prediction model is trained with support vector machine classifier on AHLS1400 in fivefold cross-validation with the best performance (ACC = 99.43%, MCC = 0.989, AUC = 0.997). The results show that AHLS-pred achieves an ACC of 94.70%, MCC of 0.894 and AUC of 0.995 on the independent testing dataset AHLS132. It demonstrates that AHLS-pred is a promising and powerful prediction method for accelerating the process of AHLSs computational identification.
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Affiliation(s)
- Jie Hu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, China
| | - Jin Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, China
| | - Jiahao Li
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, China
| | - Haidong Hu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, China
| | - Bin Wu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, China
| | - Hongqiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, China
| | - Jinfeng Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, China
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Baty JJ, Huffines JT, Stoner SN, Scoffield JA. A Commensal Streptococcus Dysregulates the Pseudomonas aeruginosa Nitrosative Stress Response. Front Cell Infect Microbiol 2022; 12:817336. [PMID: 35619650 PMCID: PMC9127344 DOI: 10.3389/fcimb.2022.817336] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 02/28/2022] [Indexed: 11/13/2022] Open
Abstract
Chronic infections in the cystic fibrosis (CF) airway are composed of both pathogenic and commensal bacteria. However, chronic Pseudomonas aeruginosa infections are the leading cause of lung deterioration in individuals with CF. Interestingly, oral commensals can translocate to the CF lung and their presence is associated with improved lung function, presumably due to their ability to antagonize P. aeruginosa. We have previously shown that one commensal, Streptococcus parasanguinis, produces hydrogen peroxide that reacts with nitrite to generate reactive nitrogen intermediates (RNI) which inhibit P. aeruginosa growth. In this study, we sought to understand the global impact of commensal-mediated RNI on the P. aeruginosa transcriptome. RNA sequencing analysis revealed that S. parasanguinis and nitrite-mediated RNI dysregulated expression of denitrification genes in a CF isolate of P. aeruginosa compared to when this isolate was only exposed to S. parasanguinis. Further, loss of a nitric oxide reductase subunit (norB) rendered an acute P. aeruginosa isolate more susceptible to S. parasanguinis-mediated RNI. Additionally, S. parasanguinis-mediated RNI inactivated P. aeruginosa aconitase activity. Lastly, we report that P. aeruginosa isolates recovered from CF individuals are uniquely hypersensitive to S. parasanguinis-mediated RNI compared to acute infection or environmental P. aeruginosa isolates. These findings illustrate that S. parasanguinis hinders the ability of P. aeruginosa to respond to RNI, which potentially prevents P. aeruginosa CF isolates from resisting commensal and host-induced RNI in the CF airway.
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Wang Y, Zheng Q, Li L, Pan L, Zhu H. Anti-Quorum-Sensing Activity of Tryptophan-Containing Cyclic Dipeptides. Mar Drugs 2022; 20:md20020085. [PMID: 35200615 PMCID: PMC8924889 DOI: 10.3390/md20020085] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/16/2022] [Accepted: 01/17/2022] [Indexed: 02/04/2023] Open
Abstract
Quorum sensing (QS) can regulate the pathogenicity of bacteria and the production of some virulence factors. It is a promising target for screening to find anti-virulence agents in the coming post-antibiotics era. Cyclo (L-Trp-L-Ser), one variety of cyclic dipeptides (CDPs), isolated from a marine bacterium Rheinheimera aquimaris, exhibited anti-QS activity against Chromobacterium violaceum CV026 and Pseudomonas aeruginosa PAO1. Unlike the CDPs composed of phenylalanine or tyrosine, the anti-QS activity has been widely studied; however, cyclo (L-Trp-L-Ser) and derivatives, containing one tryptophan unit and one non-aromatic amino acid, have not been systematically explored. Herein, the cyclo (L-Trp-L-Ser) and seven derivatives were synthesized and evaluated. All tryptophane-contained CDPs were able to decrease the production of violacein in C.violaceum CV026 and predicted as binding within the same pocket of receptor protein CviR, but in lower binding energy compared with the natural ligand C6HSL. As for P. aeruginosa PAO1, owning more complicated QS systems, these CDPs also exhibited inhibitory effects on pyocyanin production, swimming motility, biofilm formation, and adhesion. These investigations suggested a promising way to keep the tryptophan untouched and make modifications on the non-aromatic unit to increase the anti-QS activity and decrease the cytotoxicity, thus developing a novel CDP-based anti-virulence agent.
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Sriwiriyarat T, Jangkorn S, Charoenpanich J, Chinwetkitvanich S, Fongsatitkul P. Occurrence of aerobic denitrifying bacteria in integrated fixed film activated sludge system. CHEMOSPHERE 2021; 285:131504. [PMID: 34265722 DOI: 10.1016/j.chemosphere.2021.131504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 06/27/2021] [Accepted: 07/07/2021] [Indexed: 06/13/2023]
Abstract
Denitrification can be enhanced in the Integrated Fixed Film Activated System (IFAS) system by integrating media into the anoxic or aerobic zone. The simultaneous nitrification and denitrification (SND) in the biofilm layers has been reported in the aerobic zone of the IFAS system. In this study, two IFAS systems with Bioweb® media installed in the anoxic or aerobic reactor were operated in parallel to evaluate both anoxic denitrification or aerobic SND in the biofilm layers enhanced by fixed film media at three different nitrite and nitrate recirculation (NR) ratios of 75%, 100%, and 125%. The results revealed that both IFAS systems achieved the same organic and nitrogen removal efficiencies without statistically significant difference. The NR ratio of 125% enhanced slightly the denitrification in the anoxic zones of both systems. The media increased the anoxic denitrification at the NR ratio of 100%. The SND in the biofilm was found insignificant in both systems. It was evident that suspended-growth microorganisms stored substrates internally in the cells under anoxic conditions due to insufficient retention time. The aerobic denitrifiers including Chryseobacterium sp., Klebsiella pneumonia, and Pseudomonas aeruginosa were abundant in both IFAS systems providing aerobic denitrification with storage products as carbon sources. In summary, the denitrification in the anoxic zone and SND in the biofilm of the aerobic zone, both were enhanced by the fixed film media, did not contribute significantly to the IFAS system for the biological nitrogen removal because of microbial storage products and aerobic denitrification of several aerobic denitrifiers.
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Affiliation(s)
- Tongchai Sriwiriyarat
- Department of Chemical Engineering, Faculty of Engineering, Burapha University, Chonburi, 20131, Thailand.
| | - Siriprapha Jangkorn
- Division of Natural Resources and Environment, Faculty of Science and Social Sciences, Burapha University, Sakaeo, 27160, Thailand
| | - Jittima Charoenpanich
- Department of Biochemistry, Faculty of Science, Burapha University, Chonburi, 20131, Thailand
| | - Sopa Chinwetkitvanich
- Department of Sanitary Engineering, Faculty of Public Health, Mahidol University, Bangkok, 10400, Thailand
| | - Prayoon Fongsatitkul
- Department of Sanitary Engineering, Faculty of Public Health, Mahidol University, Bangkok, 10400, Thailand
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