Effect of salinity and incubation time of planktonic cells on biofilm formation, motility, exoprotease production, and quorum sensing of Aeromonas hydrophila

Aeromonas hydrophila recently has received increased attention because it is opportunistic and a primary human pathogen. A. hydrophila biofilm formation and its control are a major concern for food safety because biofilms are related to virulence. Therefore, we investigated biofilm formation, motility inhibition, quorum sensing, and exoprotease production of this opportunistic pathogen in response to various glucose concentrations from 0.05 to 2.5% (wt/vol). More than 0.05% glucose significantly impaired (P < 0.05) quorum sensing, biofilm formation, protease production, and swarming and swimming motility, whereas bacteria treated with 0.05% glucose had activity similar to that of the control (0% glucose). A stage shift biofilm assay revealed that the addition of glucose (2.5%) inhibited initial biofilm formation but not later stages. However, addition of quorum sensing molecules N-3-butanoyl-DL-homoserine lactone and N-3-hexanoyl homoserine lactone partially restored protease production, indicating that quorum sensing is controlled by glucose concentrations. Thus, glucose present in food or added as a preservative could regulate acyl-homoserine lactone quorum sensing molecules, which mediate biofilm formation and virulence in A. hydrophila.

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Inhibition of Quorum Sensing and Biofilm Formation of Esculetin on Aeromonas Hydrophila

Frontiers in Microbiology ◽

10.3389/fmicb.2021.737626 ◽

2021 ◽

Vol 12 ◽

Author(s):

Bing Sun ◽

Huaizhi Luo ◽

Huan Jiang ◽

Zhennan Wang ◽

Aiqun Jia

Keyword(s):

Quorum Sensing ◽

Aeromonas Hydrophila ◽

Biofilm Formation ◽

Laser Scanning ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Pcr Analysis ◽

Swarming Motility ◽

Gene Expression Levels ◽

Good Agreement

Quorum sensing (QS) and biofilm formation inhibition activity of esculetin on Aeromonas hydrophila SHAe 115 were evaluated. Exposure to esculetin at 25, 50, and 100μg/ml significantly inhibited the production of protease and hemolysin, the formation of biofilms and attenuated the swarming motility of A. hydrophila SHAe 115. Biofilm forming inhibition was also observed through confocal laser scanning microscopy and scanning electron microscope. Quantitative real-time PCR analysis indicated that genes positively related to QS and biofilm formation were downregulated to varying degrees, while gene (litR) negatively related to biofilm formation was significantly upregulated. The phenotypic results were in good agreement with gene expression levels. These results indicated that esculetin would be a potential QS inhibitor for A. hydrophila.

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Anti-quorum Sensing and Protective Efficacies of Naringin Against Aeromonas hydrophila Infection in Danio rerio

Frontiers in Microbiology ◽

10.3389/fmicb.2020.600622 ◽

2020 ◽

Vol 11 ◽

Author(s):

Ramanathan Srinivasan ◽

Kannan Rama Devi ◽

Sivasubramanian Santhakumari ◽

Arunachalam Kannappan ◽

Xiaomeng Chen ◽

...

Keyword(s):

Antibiotic Resistance ◽

Quorum Sensing ◽

Aeromonas Hydrophila ◽

Biofilm Formation ◽

Bacterial Load ◽

Antibiotic Resistance Genes ◽

Alternative Methods ◽

Zebrafish Model ◽

Virulence Gene Expression

It is now well known that the quorum sensing (QS) mechanism coordinates the production of several virulence factors and biofilm formation in most pathogenic microorganisms. Aeromonas hydrophila is a prime pathogen responsible for frequent outbreaks in aquaculture settings. Recent studies have also continuously reported that A. hydrophila regulates virulence factor production and biofilm formation through the QS system. In addition to the presence of antibiotic resistance genes, biofilm-mediated antibiotic resistance increases the severity of A. hydrophila infections. To control the bacterial pathogenesis and subsequent infections, targeting the QS mechanism has become one of the best alternative methods. Though very few compounds were identified as QS inhibitors against A. hydrophila, to date, the screening and identification of new and effective natural QS inhibitors is a dire necessity to control the infectious A. hydrophila. The present study endorses naringin (NA) as an anti-QS and anti-infective agent against A. hydrophila. Initially, the NA showed a concentration-dependent biofilm reduction against A. hydrophila. Furthermore, the results of microscopic analyses and quantitative virulence assays displayed the promise of NA as a potential anti-QS agent. Subsequently, the downregulation of ahh1, aerA, lip and ahyB validate the interference of NA in virulence gene expression. Furthermore, the in vivo assays were carried out in zebrafish model system to evaluate the anti-infective potential of NA. The outcome of the immersion challenge assay showed that the recovery rate of the zebrafish has substantially increased upon treatment with NA. Furthermore, the quantification of the bacterial load upon NA treatment showed a decreased level of bacterial counts in zebrafish when compared to the untreated control. Moreover, the NA treatment averts the pathogen-induced histoarchitecture damages in vital organs of zebrafish, compared to their respective controls. The current study has thus analyzed the anti-QS and anti-infective capabilities of NA and could be employed to formulate effective treatment measures against A. hydrophila infections.

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In vitro and in vivo efficacy of rosmarinic acid on quorum sensing mediated biofilm formation and virulence factor production in Aeromonas hydrophila

Biofouling ◽

10.1080/08927014.2016.1237220 ◽

2016 ◽

Vol 32 (10) ◽

pp. 1171-1183 ◽

Cited By ~ 24

Author(s):

Kannan Rama Devi ◽

Ramanathan Srinivasan ◽

Arunachalam Kannappan ◽

Sivasubramanian Santhakumari ◽

Murugan Bhuvaneswari ◽

...

Keyword(s):

Quorum Sensing ◽

Virulence Factor ◽

Aeromonas Hydrophila ◽

Rosmarinic Acid ◽

Biofilm Formation ◽

In Vivo Efficacy ◽

Factor Production ◽

Virulence Factor Production

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Insights into Bacterial Milk Spoilage with Particular Emphasis on the Roles of Heat-Stable Enzymes, Biofilms, and Quorum Sensing

Journal of Food Protection ◽

10.4315/0362-028x.jfp-18-094 ◽

2018 ◽

Vol 81 (10) ◽

pp. 1651-1660 ◽

Cited By ~ 12

Author(s):

LEI YUAN ◽

FAIZAN A. SADIQ ◽

METTE BURMØLLE ◽

TONGJIE LIU ◽

GUOQING HE

Keyword(s):

Quorum Sensing ◽

Biofilm Formation ◽

Enzyme Production ◽

Extracellular Polymeric Substances ◽

Hydrolytic Enzymes ◽

Heat Stability ◽

Planktonic Cells ◽

Psychrotrophic Bacteria ◽

Effective Strategies ◽

Heat Stable

ABSTRACT Milk spoilage caused by psychrotrophic bacteria and their heat-stable enzymes is a serious challenge for the dairy industry. In many studies, spoilage has been explored based on the simplistic view of undesirable enzymes produced by planktonic cells. Recently, biofilms and quorum sensing (QS) have been suggested as important factors in the deterioration of milk, which opens new avenues for investigation of the processes and challenges. Production and heat stability of enzymes are enhanced in biofilms, mainly because of inherent differences in physiological states and protective shielding by extracellular polymeric substances. QS plays a key role in modulating expression of hydrolytic enzymes and biofilm formation. To date, few studies have been conducted to investigate the complex interplays of enzyme production, biofilm formation, and QS. This review provides novel insights into milk spoilage with particular emphasis on the roles of biofilms and QS and summarizes potential effective strategies for controlling the spoilage of milk.

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Genistein Inhibits the Pathogenesis of Aeromonas hydrophila by Disrupting Quorum Sensing Mediated Biofilm Formation and Aerolysin Production

Frontiers in Pharmacology ◽

10.3389/fphar.2021.753581 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jing Dong ◽

Defu Zhang ◽

Jianrong Li ◽

Yongtao Liu ◽

Shun Zhou ◽

...

Keyword(s):

Quorum Sensing ◽

Aeromonas Hydrophila ◽

Biofilm Formation ◽

Cell Injury ◽

Foodborne Pathogen ◽

Opportunistic Pathogen ◽

Dependent Manner ◽

Novel Drugs ◽

Encoding Gene ◽

Dose Dependent

Aeromonas hydrophila is an opportunistic pathogen that is responsible for a variety of infectious diseases both in human and animals, particularly aquatic animals. Moreover, the pathogen has become a foodborne pathogen by transmitting from seafood to human. The abuse of antibiotics in aquaculture results in the emergence of antibiotic resistance and treatment failure. Therefore, novel approaches are urgently needed for managing resistant A. hydrophila associated infections. Aerolysin, an essential virulence factor of pathogenic A. hydrophila strain, has been identified as target developing novel drugs against pathogenesis of A. hydrophila. In the present study, genistein, without anti-A. hydrophila activity, was identified that could decrease the production of aerolysin and biofilm formation at a dose-dependent manner. Transcription of aerolysin encoding gene aerA and quorum sensing related genes ahyI and ahyR was significantly down-regulated when co-cultured with genistein. Cell viability studies demonstrated that genistein could significantly improve aerolysin mediated A549 cell injury. Furthermore, genistein could provide a remarkable protection to channel catfish infected with A. hydrophila. These findings indicate that targeting quorum sensing and virulence can be a useful approach developing drugs against A. hydrophila infections in aquaculture. Moreover, genistein can be chosen as a promising candidate in developing drugs against A. hydrophila.

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Mutation in the S-ribosylhomocysteinase (luxS) gene involved in quorum sensing affects biofilm formation and virulence in a clinical isolate of Aeromonas hydrophila

Microbial Pathogenesis ◽

10.1016/j.micpath.2008.08.007 ◽

2008 ◽

Vol 45 (5-6) ◽

pp. 343-354 ◽

Cited By ~ 39

Author(s):

Elena V. Kozlova ◽

Vsevolod L. Popov ◽

Jian Sha ◽

Sheri M. Foltz ◽

Tatiana E. Erova ◽

...

Keyword(s):

Quorum Sensing ◽

Clinical Isolate ◽

Aeromonas Hydrophila ◽

Biofilm Formation ◽

Luxs Gene

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Thymol Protects Channel Catfish from Aeromonas hydrophila Infection by Inhibiting Aerolysin Expression and Biofilm Formation

Microorganisms ◽

10.3390/microorganisms8050636 ◽

2020 ◽

Vol 8 (5) ◽

pp. 636 ◽

Cited By ~ 1

Author(s):

Jing Dong ◽

Lushan Zhang ◽

Yongtao Liu ◽

Ning Xu ◽

Shun Zhou ◽

...

Keyword(s):

Quorum Sensing ◽

Channel Catfish ◽

Aeromonas Hydrophila ◽

Biofilm Formation ◽

Cell Injury ◽

Opportunistic Pathogen ◽

Protective Effects ◽

Sensing System ◽

Quorum Sensing System

Aeromonas hydrophila is an opportunistic pathogen responsible for a number of diseases in freshwater farming. Moreover, the bacterium has been identified as a zoonotic pathogen that threatens human health. Antibiotics are widely used for treatments of infectious diseases in aquaculture. However, the abuse of antibiotics has led to the emergence of antimicrobial resistant strains. Thus, novel strategies are required against resistant A. hydrophila strains. The quorum sensing (QS) system, involved in virulence factor production and biofilm formation, is a promising target in identifying novel drugs against A. hydrophila infections. In this study, we found that thymol, at sub-inhibitory concentrations, could significantly reduce the production of aerolysin and biofilm formation by inhibiting the transcription of genes aerA, ahyI, and ahyR. These results indicate that thymol inhibits the quorum sensing system. The protective effects of thymol against A. hydrophila mediated cell injury were determined by live/dead assay and lactate dehydrogenase (LDH) release assay. Moreover, the in vivo study showed that thymol could significantly decrease the mortality of channel catfish infected with A. hydrophila. Taken together, these findings demonstrate that thymol could be chosen as a phytotherapeutic candidate for inhibiting quorum sensing system-mediated aerolysin production and biofilm formation in A. hydrophila.

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Production of Tyrosol by Candida albicans Biofilms and Its Role in Quorum Sensing and Biofilm Development

Eukaryotic Cell ◽

10.1128/ec.00219-06 ◽

2006 ◽

Vol 5 (10) ◽

pp. 1770-1779 ◽

Cited By ~ 151

Author(s):

Mohammed A. S. Alem ◽

Mohammed D. Y. Oteef ◽

T. Hugh Flowers ◽

L. Julia Douglas

Keyword(s):

Candida Albicans ◽

Quorum Sensing ◽

Biofilm Formation ◽

Dry Weight ◽

Cell Types ◽

Tube Formation ◽

Yeast Cells ◽

Planktonic Cells ◽

Biofilm Development ◽

Candida Albicans Biofilms

ABSTRACT Tyrosol and farnesol are quorum-sensing molecules produced by Candida albicans which accelerate and block, respectively, the morphological transition from yeasts to hyphae. In this study, we have investigated the secretion of tyrosol by C. albicans and explored its likely role in biofilm development. Both planktonic (suspended) cells and biofilms of four C. albicans strains, including three mutants with defined defects in the Efg 1 and Cph 1 morphogenetic signaling pathways, synthesized extracellular tyrosol during growth at 37°C. There was a correlation between tyrosol production and biomass for both cell types. However, biofilm cells secreted at least 50% more tyrosol than did planktonic cells when tyrosol production was related to cell dry weight. The addition of exogenous farnesol to a wild-type strain inhibited biofilm formation by up to 33% after 48 h. Exogenous tyrosol appeared to have no effect, but scanning electron microscopy revealed that tyrosol stimulated hypha production during the early stages (1 to 6 h) of biofilm development. Experiments involving the simultaneous addition of tyrosol and farnesol at different concentrations suggested that the action of farnesol was dominant, and 48-h biofilms formed in the presence of both compounds consisted almost entirely of yeast cells. When biofilm supernatants were tested for their abilities to inhibit or enhance germ tube formation by planktonic cells, the results indicated that tyrosol activity exceeds that of farnesol after 14 h, but not after 24 h, and that farnesol activity increases significantly during the later stages (48 to 72 h) of biofilm development. Overall, our results support the conclusion that tyrosol acts as a quorum-sensing molecule for biofilms as well as for planktonic cells and that its action is most significant during the early and intermediate stages of biofilm formation.

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N-Acylhomoserine lactones involved in quorum sensing control the type VI secretion system, biofilm formation, protease production, and in vivo virulence in a clinical isolate of Aeromonas hydrophila

Microbiology ◽

10.1099/mic.0.031575-0 ◽

2009 ◽

Vol 155 (11) ◽

pp. 3518-3531 ◽

Cited By ~ 85

Author(s):

Bijay K. Khajanchi ◽

Jian Sha ◽

Elena V. Kozlova ◽

Tatiana E. Erova ◽

Giovanni Suarez ◽

...

Keyword(s):

Quorum Sensing ◽

Aeromonas Hydrophila ◽

Biofilm Formation ◽

Secretion System ◽

Protease Production ◽

Type Vi Secretion System ◽

Double Knockout ◽

Electron Microscopic ◽

Type Vi Secretion

In this study, we delineated the role of N-acylhomoserine lactone(s) (AHLs)-mediated quorum sensing (QS) in the virulence of diarrhoeal isolate SSU of Aeromonas hydrophila by generating a double knockout ΔahyRI mutant. Protease production was substantially reduced in the ΔahyRI mutant when compared with that in the wild-type (WT) strain. Importantly, based on Western blot analysis, the ΔahyRI mutant was unable to secrete type VI secretion system (T6SS)-associated effectors, namely haemolysin coregulated protein and the valine-glycine repeat family of proteins, while significant levels of these effectors were detected in the culture supernatant of the WT A. hydrophila. In contrast, the production and translocation of the type III secretion system (T3SS) effector AexU in human colonic epithelial cells were not affected when the ahyRI genes were deleted. Solid surface-associated biofilm formation was significantly reduced in the ΔahyRI mutant when compared with that in the WT strain, as determined by a crystal violet staining assay. Scanning electron microscopic observations revealed that the ΔahyRI mutant was also defective in the formation of structured biofilm, as it was less filamentous and produced a distinct exopolysaccharide on its surface when compared with the structured biofilm produced by the WT strain. These effects of AhyRI could be complemented either by expressing the ahyRI genes in trans or by the exogeneous addition of AHLs to the ΔahyRI/ahyR+ complemented strain. In a mouse lethality experiment, 50 % attenuation was observed when we deleted the ahyRI genes from the parental strain of A. hydrophila. Together, our data suggest that AHL-mediated QS modulates the virulence of A. hydrophila SSU by regulating the T6SS, metalloprotease production and biofilm formation.

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