Exploration of the Quorum-Quenching Mechanism in Pseudomonas nitroreducens W-7 and Its Potential to Attenuate the Virulence of Dickeya zeae EC1

Abstract

Quorum quenching (QQ) is a novel, promising strategy that opens up a new perspective for controlling quorum-sensing (QS)-mediated bacterial pathogens. QQ is performed by interfering with population-sensing systems, such as by the inhibition of signal synthesis, catalysis of degrading enzymes, and modification of signals. In many Gram-negative pathogenic bacteria, a class of chemically conserved signaling molecules named N-acyl homoserine lactones (AHLs) have been widely studied. AHLs are involved in the modulation of virulence factors in various bacterial pathogens including Dickeya zeae. Dickeya zeae is the causal agent of plant-rot disease of bananas, rice, maize, potatoes, etc., causing enormous economic losses of crops. In this study, a highly efficient AHL-degrading bacterial strain W-7 was isolated from activated-sludge samples and identified as Pseudomonas nitroreducens. Strain W-7 revealed a superior ability to degrade N-(3-oxododecanoyl)-l-homoserine lactone (OdDHL) and completely degraded 0.2 mmol/L of OdDHL within 48 h. Gas chromatography-mass spectrometry (GC-MS) identified N-cyclohexyl-propanamide as the main intermediate metabolite during AHL biodegradation. A metabolic pathway for AHL in strain W-7 was proposed based on the chemical structure of AHL and intermediate products. In addition to the degradation of OdDHL, this strain was also found to be capable of degrading a wide range of AHLs including N-(3-oxohexanoyl)-l-homoserine lactone (OHHL), N-(3-oxooctanoyl)-l-homoserine lactone (OOHL), and N-hexanoyl-l-homoserine lactone (HHL). Moreover, the application of strain W-7 as a biocontrol agent could substantially attenuate the soft rot caused by D. zeae EC1 to suppress tissue maceration in various host plants. Similarly, the application of crude enzymes of strain W-7 significantly reduced the disease incidence and severity in host plants. These original findings unveil the biochemical aspects of a highly efficient AHL-degrading bacterial isolate and provide useful agents that exhibit great potential for the control of infectious diseases caused by AHL-dependent bacterial pathogens.

Bacterial Quorum-Quenching Lactonase Hydrolyzes Fungal Mycotoxin and Reduces Pathogenicity of Penicillium expansum—Suggesting a Mechanism of Bacterial Antagonism

“…Here, we used a highly active and stable AHL lactonase (PPH-G55V) [53] to test these effects. Our results suggest a new function for bacterial AHL lactonases, with a hydrolytic mechanism, thus far known to degrade mainly bacterial AHLs, QS signaling molecules and act as quorum-quenching enzymes that reduce virulence plant pathogens [27,32,33,69,70]. Patulin is a lactone-based fungal mycotoxin, shown to be related to pathogenicity affecting mycelium growth, and linked to host-pathogen-microbe interaction [58,[71][72][73].…”

Quorum quenching of Streptococcus mutans via the nano-quercetin-based antimicrobial photodynamic therapy as a potential target for cariogenic biofilm

“…Hence, disruption of S. mutans QS system has been proposed as a new anti-biofilm infection approach. Using QQ is considered to be one of the most promising methods for disrupting the QS systems and attenuating bacterial virulence [ 60 , 61 ]. As Mion et al [ 60 ] reported, QQ not only constitutes an interesting therapeutic strategy to fight against bacterial infections but also restricts the consequences of antibiotic resistance.…”

Quorum Quenching Strains Isolated from the Microbiota of Sea Anemones and Holothurians Attenuate Vibriocorallilyticus Virulence Factors and Reduce Mortality in Artemiasalina

“…carotovovum in carrots, potatoes and Chinese cabbage [ 23 ]. Pseudomonas QQ-strains have also been recently used as biocontrol tools in agriculture [ 22 , 24 ], but this report shows its potential also in aquaculture. Overall, these results demonstrate the potential effectiveness of using AHL degradation in the fight against vibriosis in aquaculture, as well as marine invertebrate microbiota as a source of bacteria with QQ activity.…”

“…strain and is expressed in the agricultural pathogen Erwinia carotovora that causes a decrease in the production of enzymatic activity, as well as an attenuation in its virulence [ 14 ]. Subsequently, many AHL-degrading enzymes have been identified, some of which have shown the potential to be used as biocontrol agents in aquaculture [ 15 , 16 , 17 , 18 ] and agriculture [ 19 , 20 , 21 , 22 , 23 , 24 ].…”