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1.
Chemosphere ; 262: 127602, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32750589

RESUMO

A 1 L lab-scale anaerobic ammonium oxidation (anammox) biofilm reactor with nitrogen loading rate of 0.11 g/L d was run for 110 days with the operation temperature declining from 36 °C to 15 °C. The total inorganic nitrogen removal efficiency showed a reduction from 80% to 66%, when the temperature declined from 36 °C to 15 °C. N-acyl-l-homoserine lactones (AHLs) concentrations, especially C8-HSL and C6-HSL, declined in both water and biomass phases, and this decline indicated that the quorum sensing weakened. Microbial community analysis revealed that Candidatus Kuenenia was the predominant anammox bacteria during the entire operating period. The abundance of Candidatus Kuenenia increased from 1.43% to 22.89% when the temperature decreasing from 36 °C to 15 °C. The correlation between microbial genus and AHLs was complicated. Overall, the temperature decrease weakened the quorum sensing so that the nitrogen removal performance deteriorated, and increasing the anammox activity might be an efficient way to improve performance.


Assuntos
Reatores Biológicos/microbiologia , Homosserina/metabolismo , Lactonas/metabolismo , Microbiota , Bactérias/classificação , Biofilmes , Biomassa , Nitrogênio , Oxirredução , Percepção de Quorum , Temperatura
2.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2459-2462, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018504

RESUMO

We have recently postulated that certain bacterial cells within their biofilms are equipped with electrically-polarized and elastic helical fibers called amyloid fibrils which allow the cells to transmit electromagnetic (EM) signal to their surrounding environment through mechanical vibration of these fibrils. A novel and theoretical Multiphysics model based on a coupled system of electrical and mechanical structures is proposed here enabling prediction of efficient signal generation in the radio frequency range among the cells. Next, to demonstrate the advantage of EM-based communication, using communication channel theory, we have compared performance of EM signaling with its biochemical counterpart (quorum sensing) and shown that EM signaling provides much higher data rate, 4 to 5 orders of magnitude. Thus, it could be potentially more efficient and a preferred method for communication among cells. In quorum sensing, biological cells release auto-inducers intercepted by the adjacent cells as a purposeful message signal.


Assuntos
Biofilmes , Percepção de Quorum , Bactérias , Fenômenos Eletromagnéticos , Transdução de Sinais
3.
J Environ Sci (China) ; 98: 179-185, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33097150

RESUMO

Bioaugmentation of denitrifying bacteria can serve as a promising technique to improve nutrient removal during wastewater treatment. While denitrification inhibition by bacterial quorum sensing (QS) in Pseudomonas aeruginosa has been indicated, the application of bacterial QS disruption to improve nitrate removal from wastewater has not been investigated. In this study, the effect of bioaugmentation of P. aeruginosa SD-1 on nitrate removal in sequencing batch reactors that treat nitrate rich wastewater was assessed. Additionally, the potential of a quorum sensing inhibitor (QSI) to improve denitrification following bacterial bioaugmentation was evaluated. Curcumin, a natural plant extract, was used as a QSI. The chemical oxygen demand (COD) and initial nitrate concentration of the influent were 700±20 mg/L and 200±10 mg/L respectively, and their respective concentrations in the effluent were 56.9±3.2 mg/L and 9.0±3.2 mg/L. Thus, the results revealed that bioaugmentation of P. aeruginosa SD-1 resulted in an increased nitrate removal to 82%±1%. Further, nitrate was almost completely removed following the addition of the QSI, and activities of nitrate reductase and nitrite reductase increased by 88%±2% and 74%±2% respectively. The nitrogen mass balance indicated that aerobic denitrification was employed as the main pathway for nitrogen removal in the reactors. The results imply that bioaugmentation and modulation of QS in denitrifying bacteria, through the use of a QSI, can enhance nitrate removal during wastewater treatment.


Assuntos
Percepção de Quorum , Águas Residuárias , Reatores Biológicos , Desnitrificação , Nitratos , Águas Residuárias/análise
4.
Nat Commun ; 11(1): 5371, 2020 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-33097715

RESUMO

Autoinducer-2 (AI-2) is a quorum sensing signal that mediates communication within and between many bacterial species. However, its known receptors (LuxP and LsrB families) are not found in all the bacteria capable of responding to this signaling molecule. Here, we identify a third type of AI-2 receptor, consisting of a dCACHE domain. AI-2 binds to the dCACHE domain of chemoreceptors PctA and TlpQ of Pseudomonas aeruginosa, thus inducing chemotaxis and biofilm formation. Boron-free AI-2 is the preferred ligand for PctA and TlpQ. AI-2 also binds to the dCACHE domains of histidine kinase KinD from Bacillus subtilis and diguanylate cyclase rpHK1S-Z16 from Rhodopseudomonas palustris, enhancing their enzymatic activities. dCACHE domains (especially those belonging to a subfamily that includes the AI-2 receptors identified in the present work) are present in a large number of bacterial and archaeal proteins. Our results support the idea that AI-2 serves as a widely used signaling molecule in the coordination of cell behavior among prokaryotic species.


Assuntos
Quimiotaxia/fisiologia , Homosserina/análogos & derivados , Homosserina/metabolismo , Lactonas/metabolismo , Células Procarióticas/metabolismo , Proteínas Arqueais , Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biofilmes/crescimento & desenvolvimento , Liases de Carbono-Enxofre/genética , Liases de Carbono-Enxofre/metabolismo , Proteínas de Transporte/metabolismo , Escherichia coli/metabolismo , Proteínas de Escherichia coli , Homosserina/química , Homosserina/genética , Lactonas/química , Ligantes , Fósforo-Oxigênio Liases , Pseudomonas aeruginosa/metabolismo , Percepção de Quorum , Rodopseudomonas/metabolismo , Transdução de Sinais/fisiologia
5.
Rev Soc Bras Med Trop ; 53: e20200399, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33111915

RESUMO

INTRODUCTION: Pseudomonas aeruginosa is an opportunistic pathogen associated with healthcare-related infections, affecting mainly patients with underlying diseases and immunosuppression. This microorganism has several virulence mechanisms that favour its pathogenesis, including the production of biofilm. This study aimed to analyze the phenotypic production of biofilms, the occurrence of quorum sensing (QS) genes, and the clonal profile of clinical isolates of P. aeruginosa from colonized/infected patients in a tertiary hospital in Recife-PE. METHODS: We obtained 21 isolates that were classified as infection isolates (II), and 10 colonization isolates (CI). The phenotypic analysis for biofilm production was performed quantitatively. The QS genes were detected by specific PCRs, and the clonal profile was assessed using ERIC-PCR. RESULTS: Of the 31 isolates, 58.1 % (18/31) were biofilm producers, of which 70 % (7/10) were CI and classified as weakly adherent; 52.4 % (11/21) of the II produced biofilms, and were classified as weak (38.1 %, (8/21)), moderate (9.5 %, (2/21)), and strongly adherent (4.8 %, (1/21)). All isolates harbored the QS genes analyzed. In the clonal analysis, 26 distinct genetic profiles were identified, highlighting the presence of a clone in four samples, i.e., one infection isolate, and 3 colonization isolates. CONCLUSIONS: The detection of biofilm formation is important in P. aeruginosa in addition to the identification of colonization and infection isolates, especially from complex environments such as ICUs. Further, we define a strategy for monitoring and analyzing P. aeruginosa strains that can potentially cause infections in hospitalized patients.


Assuntos
Infecções por Pseudomonas , Pseudomonas aeruginosa , Antibacterianos/farmacologia , Biofilmes , Genótipo , Humanos , Fenótipo , Pseudomonas aeruginosa/genética , Percepção de Quorum/efeitos dos fármacos , Virulência/genética , Fatores de Virulência
6.
PLoS Pathog ; 16(9): e1008867, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32925969

RESUMO

Surface attachment, an early step in the colonization of multiple host environments, activates the virulence of the human pathogen P. aeruginosa. However, the downstream toxins that mediate surface-dependent P. aeruginosa virulence remain unclear, as do the signaling pathways that lead to their activation. Here, we demonstrate that alkyl-quinolone (AQ) secondary metabolites are rapidly induced upon surface association and act directly on host cells to cause cytotoxicity. Surface-induced AQ cytotoxicity is independent of other AQ functions like quorum sensing or PQS-specific activities like iron sequestration. We further show that packaging of AQs in outer-membrane vesicles (OMVs) increases their cytotoxicity to host cells but not their ability to stimulate downstream quorum sensing pathways in bacteria. OMVs lacking AQs are significantly less cytotoxic, suggesting these molecules play a role in OMV cytotoxicity, in addition to their previously characterized role in OMV biogenesis. AQ reporters also enabled us to dissect the signal transduction pathways downstream of the two known regulators of surface-dependent virulence, the quorum sensing receptor, LasR, and the putative mechanosensor, PilY1. Specifically, we show that PilY1 regulates surface-induced AQ production by repressing the AlgR-AlgZ two-component system. AlgR then induces RhlR, which can induce the AQ biosynthesis operon under specific conditions. These findings collectively suggest that the induction of AQs upon surface association is both necessary and sufficient to explain surface-induced P. aeruginosa virulence.


Assuntos
Proteínas de Bactérias/metabolismo , Infecções por Pseudomonas/metabolismo , Pseudomonas aeruginosa , Quinolonas/farmacologia , Percepção de Quorum/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Fatores de Virulência/metabolismo , Células A549 , Animais , Humanos , Camundongos , Infecções por Pseudomonas/patologia , Pseudomonas aeruginosa/metabolismo , Pseudomonas aeruginosa/patogenicidade
7.
PLoS Genet ; 16(9): e1008744, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32956370

RESUMO

Qsp1 is a secreted quorum sensing peptide required for virulence of the fungal meningitis pathogen Cryptococcus neoformans. Qsp1 functions to control cell wall integrity in vegetatively growing cells and also functions in mating. Rather than acting on a cell surface receptor, Qsp1 is imported to act intracellularly via the predicted oligopeptide transporter Opt1. Here, we identify a transcription factor network as a target of Qsp1. Using whole-genome chromatin immunoprecipitation, we find Qsp1 controls the genomic associations of three transcription factors to genes whose outputs are regulated by Qsp1. One of these transcription factors, Cqs2, is also required for the action of Qsp1 during mating, indicating that it might be a shared proximal target of Qsp1. Consistent with this hypothesis, deletion of CQS2 impacts the binding of other network transcription factors specifically to Qsp1-regulated genes. These genetic and genomic studies illuminate mechanisms by which an imported peptide acts to modulate eukaryotic gene expression.


Assuntos
Cryptococcus neoformans/genética , Percepção de Quorum/genética , Fatores de Transcrição/genética , Ciclo Celular/genética , Parede Celular/metabolismo , Criptococose/microbiologia , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica/genética , Genômica , Meningite Fúngica/genética , Peptídeos/genética , Fatores de Transcrição/metabolismo , Virulência/genética , Fatores de Virulência/genética
8.
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi ; 36(9): 776-781, 2020 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-32967760

RESUMO

Objective To explore the regulatory effect of quorum sensing molecule N-3-oxodecanoyl-L-homoserine lactone (3-oxo-C10-HSL) on lipopolysaccharide (LPS)-induced inflammation in RAW264.7 macrophages. Methods RAW264.7 macrophages were divided into experimental group, control group and blank group. The experimental group was treated with different concentrations of 3-oxo-C10-HSL and LPS; the control group was treated with DMSO and LPS; and the blank group was treated with DMSO and PBS. Cells and supernatants were collected after 12 hours of stimulation. The mRNA expression of interleukin-6 (IL-6), interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1) were detected by real-time quantitative PCR, and the protein levels of IL-6 and TNF-α in supernatant were detected by ELSIA. Further, 25 µmol/L 3-oxo-C10-HSL and 100 ng/mL LPS were used to stimulate the cells for 15, 30 and 60 minutes, and the phosphorylation of nuclear factor κBp65 (NF-κBp65) was detected by Western blot analysis. Results The 3-oxo-C10-HSL could decrease the mRNA levels of IL-6, IL-1ß, TNF-α, MCP-1 and the protein levels of IL-6 and TNF-α in LPS-treated RAW264.7 macrophages in a dose-dependent manner. In addition, 3-oxo-C10-HSL could inhibit the phosphorylation of NF-κBp65 induced by LPS. Conclusion 3-oxo-C10-HSL can alleviate LPS-induced inflammatory responses in RAW264.7 macrophages by inhibiting activation of NF-κB signaling pathway.


Assuntos
Percepção de Quorum , 4-Butirolactona/análogos & derivados , Lipopolissacarídeos , Macrófagos , NF-kappa B , Fator de Necrose Tumoral alfa/genética
9.
PLoS One ; 15(8): e0238218, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32845909

RESUMO

One of the most studied mechanisms involved in bacterial evolution and diversification is conjugative transfer (CT) of plasmids. Plasmids able to transfer by CT often encode beneficial traits for bacterial survival under specific environmental conditions. Rhizobium etli CFN42 is a Gram-negative bacterium of agricultural relevance due to its symbiotic association with Phaseolus vulgaris through the formation of Nitrogen-fixing nodules. The genome of R. etli CFN42 consists of one chromosome and six large plasmids. Among these, pRet42a has been identified as a conjugative plasmid. The expression of the transfer genes is regulated by a quorum sensing (QS) system that includes a traI gene, which encodes an acyl-homoserine lactone (AHL) synthase and two transcriptional regulators (TraR and CinR). Recently, we have shown that pRet42a can perform CT on the root surface and inside nodules. The aim of this work was to determine the role of plant-related compounds in the CT of pRet42a. We found that bean root exudates or root and nodule extracts induce the CT of pRet42a in the plant rhizosphere. One possibility is that these compounds are used as nutrients, allowing the bacteria to increase their growth rate and reach the population density leading to the activation of the QS system in a shorter time. We tested if P. vulgaris compounds could substitute the bacterial AHL synthesized by TraI, to activate the conjugation machinery. The results showed that the transfer of pRet42a in the presence of the plant is dependent on the bacterial QS system, which cannot be substituted by plant compounds. Additionally, individual compounds of the plant exudates were evaluated; among these, some increased and others decreased the CT. With these results, we suggest that the plant could participate at different levels to modulate the CT, and that some compounds could be activating genes in the conjugation machinery.


Assuntos
Conjugação Genética/genética , Compostos Fitoquímicos/farmacologia , Plasmídeos/genética , Rhizobium etli/genética , DNA Helicases/genética , DNA Helicases/metabolismo , Phaseolus/química , Phaseolus/microbiologia , Percepção de Quorum/fisiologia , Rizosfera , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
10.
PLoS Genet ; 16(8): e1008992, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32797092

RESUMO

Bacterial virulence factors facilitate host colonization and set the stage for the evolution of parasitic and mutualistic interactions. The Sodalis-allied clade of bacteria exhibit striking diversity in the range of both plant and animal feeding insects they inhabit, suggesting the appropriation of universal molecular mechanisms that facilitate establishment. Here, we report on the infection of the tsetse fly by free-living Sodalis praecaptivus, a close relative of many Sodalis-allied symbionts. Key genes involved in quorum sensing, including the homoserine lactone synthase (ypeI) and response regulators (yenR and ypeR) are integral for the benign colonization of S. praecaptivus. Mutants lacking ypeI, yenR and ypeR compromised tsetse survival as a consequence of their inability to repress virulence. Genes under quorum sensing, including homologs of the binary insecticidal toxin PirAB and a putative symbiosis-promoting factor CpmAJ, demonstrated negative and positive impacts, respectively, on tsetse survival. Taken together with results obtained from experiments involving weevils, this work shows that quorum sensing virulence suppression plays an integral role in facilitating the establishment of Sodalis-allied symbionts in diverse insect hosts. This knowledge contributes to the understanding of the early evolutionary steps involved in the formation of insect-bacterial symbiosis. Further, despite having no established history of interaction with tsetse, S. praecaptivus can infect reproductive tissues, enabling vertical transmission through adenotrophic viviparity within a single host generation. This creates an option for the use of S. praecaptivus in the biocontrol of insect disease vectors via paratransgenesis.


Assuntos
Percepção de Quorum/genética , Moscas Tsé-Tsé/genética , Fatores de Virulência/genética , 4-Butirolactona/análogos & derivados , 4-Butirolactona/biossíntese , 4-Butirolactona/genética , Animais , Enterobacteriaceae/genética , Enterobacteriaceae/patogenicidade , Humanos , Insetos Vetores/genética , Insetos Vetores/microbiologia , Insetos/genética , Simbiose/genética , Moscas Tsé-Tsé/microbiologia
11.
PLoS One ; 15(8): e0238151, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32833990

RESUMO

Bacteria often possess relatively flexible genome structures and adaptive genetic variants that allow survival in unfavorable growth conditions. Bacterial survival tactics in disadvantageous microenvironments include mutations that are beneficial against threats in their niche. Here, we report that the aerobic rice bacterial pathogen Burkholderia glumae BGR1 changes a specific gene for improved survival in static culture conditions. Static culture triggered formation of colony variants with deletions or point mutations in the gene bspP (BGLU_RS28885), which putatively encodes a protein that contains PDC2, PAS-9, SpoIIE, and HATPase domains. The null mutant of bspP survived longer in static culture conditions and produced a higher level of bis-(3'-5')-cyclic dimeric guanosine monophosphate than the wild type. Expression of the bacterial cellulose synthase regulator (bcsB) gene was upregulated in the mutant, consistent with the observation that the mutant formed pellicles faster than the wild type. Mature pellicle formation was observed in the bspP mutant before pellicle formation in wild-type BGR1. However, the population density of the bspP null mutant decreased substantially when grown in Luria-Bertani medium with vigorous agitation due to failure of oxalate-mediated detoxification of the alkaline environment. The bspP null mutant was less virulent and exhibited less effective colonization of rice plants than the wild type. All phenotypes caused by mutations in bspP were recovered to those of the wild type by genetic complementation. Thus, although wild-type B. glumae BGR1 prolonged viability by spontaneous mutation under static culture conditions, such genetic changes negatively affected colonization in rice plants. These results suggest that adaptive gene sacrifice of B. glumae to survive unfavorable growth conditions is not always desirable as it can adversely affect adaptability in the host.


Assuntos
Adaptação Biológica/genética , Burkholderia/genética , Burkholderia/metabolismo , Burkholderia/patogenicidade , Regulação Bacteriana da Expressão Gênica/genética , Genoma Bacteriano/genética , Genômica/métodos , Mutação , Oryza/microbiologia , Doenças das Plantas/microbiologia , Percepção de Quorum/genética , Virulência/genética
12.
Proc Natl Acad Sci U S A ; 117(37): 23001-23010, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32855303

RESUMO

The unique extracellular electron transfer (EET) ability has positioned electroactive bacteria (EAB) as a major class of cellular chassis for genetic engineering aimed at favorable environmental, energy, and geoscience applications. However, previous efforts to genetically enhance EET ability have often impaired the basal metabolism and cellular growth due to the competition for the limited cellular resource. Here, we design a quorum sensing-based population-state decision (PSD) system for intelligently reprogramming the EET regulation system, which allows the rebalanced allocation of the cellular resource upon the bacterial growth state. We demonstrate that the electron output from Shewanella oneidensis MR-1 could be greatly enhanced by the PSD system via shifting the dominant metabolic flux from initial bacterial growth to subsequent EET enhancement (i.e., after reaching a certain population-state threshold). The strain engineered with this system achieved up to 4.8-fold EET enhancement and exhibited a substantially improved pollutant reduction ability, increasing the reduction efficiencies of methyl orange and hexavalent chromium by 18.8- and 5.5-fold, respectively. Moreover, the PSD system outcompeted the constant expression system in managing EET enhancement, resulting in considerably enhanced electron output and pollutant bioreduction capability. The PSD system provides a powerful tool for intelligently managing extracellular electron transfer and may inspire the development of new-generation smart bioelectrical devices for various applications.


Assuntos
Transporte de Elétrons/fisiologia , Shewanella/fisiologia , Respiração Celular/fisiologia , Cromo/metabolismo , Elétrons , Percepção de Quorum/fisiologia , Shewanella/metabolismo
13.
J Environ Pathol Toxicol Oncol ; 39(2): 125-136, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32749122

RESUMO

Biofilms are a collective of multiple types of bacteria that develop on a variety of surfaces. Biofilm development results in heightened resistance to antibiotics. Quorum sensing plays an important role in biofilm development as it is one of the common communication mechanisms within cells, which balances and stabilizes the environment, when the amount of bacteria increases. Because of the important implications of the roles biofilms play in infectious diseases, it is crucial to investigate natural antibacterial agents that are able to regulate biofilm formation and development. Various studies have suggested that natural plant products have the potential to suppress bacterial growth and exhibit chemopreventive traits in the modulation of biofilm development. In this review, we discuss and collate potential antibiofilm drugs and biological molecules from natural sources, along with their underlying mechanisms of action. In addition, we also discuss the antibiofilm drugs that are currently under clinical trials and highlight their potential future uses.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Infecções/tratamento farmacológico , Extratos Vegetais/farmacologia , Antibacterianos/uso terapêutico , Biofilmes/crescimento & desenvolvimento , Interações Hospedeiro-Patógeno , Humanos , Infecções/microbiologia , Extratos Vegetais/uso terapêutico , Percepção de Quorum/efeitos dos fármacos
14.
PLoS Biol ; 18(8): e3000814, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32797039

RESUMO

Plasmid-mediated horizontal gene transfer of antibiotic resistance and virulence in pathogenic bacteria underlies a major public health issue. Understanding how, in the absence of antibiotic-mediated selection, plasmid-bearing cells avoid being outnumbered by plasmid-free cells is key to developing counterstrategies. Here, we quantified the induction of the plasmidial sex pheromone pathway of Enterococcus faecalis to show that the integration of the stimulatory (mate-sensing) and inhibitory (self-sensing) signaling modules from the pCF10 conjugative plasmid provides a precise measure of the recipient-to-donor ratio, agnostic to variations in population size. Such ratiometric control of conjugation favors vertical plasmid transfer under low mating likelihood and allows activation of conjugation functions only under high mating likelihood. We further show that this strategy constitutes a cost-effective investment into mating effort because overstimulation produces unproductive self-aggregation and growth rate reduction. A mathematical model suggests that ratiometric control of conjugation increases plasmid fitness and predicts a robust long-term, stable coexistence of donors and recipients. Our results demonstrate how population-level parameters can control transfer of antibiotic resistance in bacteria, opening the door for biotic control strategies.


Assuntos
Proteínas de Bactérias/genética , Resistência Microbiana a Medicamentos/genética , Enterococcus faecalis/genética , Transferência Genética Horizontal , Feromônios/genética , Percepção de Quorum/efeitos dos fármacos , Antibacterianos/farmacologia , Carga Bacteriana , Proteínas de Bactérias/metabolismo , Conjugação Genética , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/crescimento & desenvolvimento , Enterococcus faecalis/metabolismo , Expressão Gênica , Aptidão Genética , Modelos Estatísticos , Feromônios/biossíntese , Plasmídeos/química , Plasmídeos/metabolismo , Percepção de Quorum/genética , Virulência
15.
PLoS Biol ; 18(8): e3000805, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32810152

RESUMO

Antibiotics are losing efficacy due to the rapid evolution and spread of resistance. Treatments targeting bacterial virulence factors have been considered as alternatives because they target virulence instead of pathogen viability, and should therefore exert weaker selection for resistance than conventional antibiotics. However, antivirulence treatments rarely clear infections, which compromises their clinical applications. Here, we explore the potential of combining antivirulence drugs with antibiotics against the opportunistic human pathogen Pseudomonas aeruginosa. We combined two antivirulence compounds (gallium, a siderophore quencher, and furanone C-30, a quorum sensing [QS] inhibitor) together with four clinically relevant antibiotics (ciprofloxacin, colistin, meropenem, tobramycin) in 9×9 drug concentration matrices. We found that drug-interaction patterns were concentration dependent, with promising levels of synergies occurring at intermediate drug concentrations for certain drug pairs. We then tested whether antivirulence compounds are potent adjuvants, especially when treating antibiotic resistant (AtbR) clones. We found that the addition of antivirulence compounds to antibiotics could restore growth inhibition for most AtbR clones, and even abrogate or reverse selection for resistance in five drug combination cases. Molecular analyses suggest that selection against resistant clones occurs when resistance mechanisms involve restoration of protein synthesis, but not when efflux pumps are up-regulated. Altogether, our work provides a first systematic analysis of antivirulence-antibiotic combinatorial treatments and suggests that such combinations have the potential to be both effective in treating infections and in limiting the spread of antibiotic resistance.


Assuntos
Antibacterianos/farmacologia , Ciprofloxacino/farmacologia , Colistina/farmacologia , Furanos/farmacologia , Gálio/farmacologia , Meropeném/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Tobramicina/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Combinação de Medicamentos , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Sinergismo Farmacológico , Humanos , Testes de Sensibilidade Microbiana , Biossíntese de Proteínas/efeitos dos fármacos , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pseudomonas aeruginosa/metabolismo , Percepção de Quorum/efeitos dos fármacos , Virulência
16.
Water Res ; 184: 116147, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32763514

RESUMO

Biofilm start-up is a critical and time-consuming process in moving bed biofilm reactors (MBBRs), with the procedure beginning with bacteria being statically bound on surfaces. Studies addressing this critical process have mainly focused on constructing models based on single strains, although consideration of the unstable adhesion process of structured bacterial communities remains underexplored. In this study, impedance based real-time cell analysis (RTCA) was employed to quantitatively characterize the unstable adhesion process of structured bacterial communities collected from the aerobic tanks of eight full-scale wastewater treatment plants (WWTPs). The unstable adhesion time ranged from 8.85 ± 1.53 h to 17.06 ± 0.64 h, indicating significant differences in bacterial colonization properties. Using principal components analysis (PCA), Na+, K+ and proteins were found to significantly influence the biofilm unstable adhesion process. Furthermore, the differences in unstable adhesion times were closely related to the abundance of the most abundant operational taxonomic units (OTUs). The dominant OTUs mainly belonged to Aeromonadaceae and Enterobacteriaceae, with 73% found to be negatively corelated with unstable adhesion time. Furthermore, bacterial assembly during the initial adhesion phase was driven by bacterial interactions and key OTUs (exhibiting maximum connectivity in phylogenetic molecular ecological networks (pMENs)). Analysis of pMENs indicated that bacterial cooperation was a dominant factor in the initial adhesion, which may involve bacterial co-colonization, co-aggregation and communication. Considering keystone taxa were not identified, OTUs with max connectivity in pMENs were considered as key species. Although these key species play important roles in the connection of networks, their relative abundances were low and no significant relationships were observed with the unstable adhesion time. Overall, unstable adhesion in MBBRs is regulated by the dominant bacterial species and the alleviation of environmental variables by repulsive forces, providing potential strategies of dosing quorum sensing signals and key cations at the initial adhesion phase in reactors, to facilitate initial biofilm formation.


Assuntos
Biofilmes , Águas Residuárias , Bactérias/genética , Aderência Bacteriana , Filogenia , Percepção de Quorum
17.
Proc Natl Acad Sci U S A ; 117(35): 21647-21657, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32817433

RESUMO

Many bacteria cycle between sessile and motile forms in which they must sense and respond to internal and external signals to coordinate appropriate physiology. Maintaining fitness requires genetic networks that have been honed in variable environments to integrate these signals. The identity of the major regulators and how their control mechanisms evolved remain largely unknown in most organisms. During four different evolution experiments with the opportunist betaproteobacterium Burkholderia cenocepacia in a biofilm model, mutations were most frequently selected in the conserved gene rpfR RpfR uniquely integrates two major signaling systems-quorum sensing and the motile-sessile switch mediated by cyclic-di-GMP-by two domains that sense, respond to, and control the synthesis of the autoinducer cis-2-dodecenoic acid (BDSF). The BDSF response in turn regulates the activity of diguanylate cyclase and phosphodiesterase domains acting on cyclic-di-GMP. Parallel adaptive substitutions evolved in each of these domains to produce unique life history strategies by regulating cyclic-di-GMP levels, global transcriptional responses, biofilm production, and polysaccharide composition. These phenotypes translated into distinct ecology and biofilm structures that enabled mutants to coexist and produce more biomass than expected from their constituents grown alone. This study shows that when bacterial populations are selected in environments challenging the limits of their plasticity, the evolved mutations not only alter genes at the nexus of signaling networks but also reveal the scope of their regulatory functions.


Assuntos
Biofilmes/crescimento & desenvolvimento , Burkholderia cenocepacia/genética , Percepção de Quorum/genética , Proteínas de Bactérias/metabolismo , Burkholderia cenocepacia/crescimento & desenvolvimento , GMP Cíclico/análogos & derivados , GMP Cíclico/genética , Evolução Molecular Direcionada/métodos , Regulação Bacteriana da Expressão Gênica/genética , Mutação/genética , Fenótipo , Transdução de Sinais/genética , Virulência/genética
18.
Nat Commun ; 11(1): 3659, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32694598

RESUMO

As synthetic biocircuits become more complex, distributing computations within multi-strain microbial consortia becomes increasingly beneficial. However, designing distributed circuits that respond predictably to variation in consortium composition remains a challenge. Here we develop a two-strain gene circuit that senses and responds to which strain is in the majority. This involves a co-repressive system in which each strain produces a signaling molecule that signals the other strain to down-regulate production of its own, orthogonal signaling molecule. This co-repressive consortium links gene expression to ratio of the strains rather than population size. Further, we control the cross-over point for majority via external induction. We elucidate the mechanisms driving these dynamics by developing a mathematical model that captures consortia response as strain fractions and external induction are varied. These results show that simple gene circuits can be used within multicellular synthetic systems to sense and respond to the state of the population.


Assuntos
Engenharia Celular/métodos , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Consórcios Microbianos/genética , Percepção de Quorum/genética , Redes Reguladoras de Genes , Transdução de Sinais/genética , Biologia Sintética/métodos
19.
Bioresour Technol ; 315: 123862, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32702577

RESUMO

A facultative bacterium Microbacterium sp. (QQ strain) was found significantly mitigated membrane biofouling and also increased methane production. It was found genera Nitrospira, norank-c-Bacterodetes vadinHA17, Trichococcus and family Anaerolineaceae were likely responsible for membrane biofouling. The presence of QQ strain increased the total abundance of fermentative and acetogenic genera by 0.61% and 379.61%, respectively, but had a minor effect on the abundance of methanogens. The increased methane production was likely due to the strengthened methanogenic activity and more available substrates. Homo-acetogenic Treponema was enriched (9.01%) in the presence of QQ strain suggesting that apart from hydrogenotrophic methanogenic pathway, extra CH4 could be also produced from the additional acetate synthesized via homo-acetogenic pathway. This study advances knowledge about the effects of QQ strain on microbial communities, microbiota biofouling behavior and anaerobic fermentation process in AnMBRs.


Assuntos
Incrustação Biológica , Percepção de Quorum , Anaerobiose , Reatores Biológicos , Metano
20.
Bioresour Technol ; 315: 123863, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32717518

RESUMO

Anammox as a novel biological process in natural nitrogen cycle has been introduced into wastewater treatment process. However, the regulation mechanism of anammox metabolism remained to be investigated. In this study, the specific quorum sensing (QS) signaling molecules for mediating anammox were identified in anammox activity tests. Anammox was valve-regulated by the collaboration of QS signaling molecules N-butyryl-homoserine lactone (C14-HSL) and N-(3-oxotetradecanoyl)-homoserine lactone (3-oxo-C14-HSL), and prompted with the C14-HSL/3-oxo-C14-HSL mole ratio above 1.0. Moreover, the ratio of chemical oxygen demand to total nitrogen (C/N) was identified as an effective regulator for the distribution of C14-HSL and 3-oxo-C14-HSL. An engineering method for control anammox through regulating C/N ratio was proposed and demonstrated based on the performance of two microaerobic reactors treating piggery wastewater and anammox activity tests. The discovery should be of great significance to understanding the social behaviors of anammox bacteria in organic wastewater treatment processes.


Assuntos
4-Butirolactona , Percepção de Quorum , Bactérias , Crescimento Quimioautotrófico , Nitrogênio , Transdução de Sinais
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