Pseudomonas aeruginosa inhibits quorum-sensing mechanisms of soft rot pathogen Lelliottia amnigena RCE to regulate its virulence factors and biofilm formation

Abstract

The quorum-sensing (QS) cascade is responsible for the colonization and phenotypic behavior of the pathogenic organism and the regulation of diverse signal molecules. The disruption of the quorum-sensing system is an effective strategy to overcome the possibility of antibiotic resistance development in the pathogen. The quorum quenching does not kill the microbes. Instead, it hinders the expression of pathogenic traits. In the present experiment, Pseudomonas aeruginosa RKC1 was used to extract the metabolites responsible for quorum-sensing inhibition in soft rot pathogen Lelliottia amnigena RCE. During the initial screening, P. aeruginosa RKC1 was found to be most promising and inhibits violacein of Chromobacterium violaceum MTCC2656 pyocyanin, swarming-swimming motility of P. aeruginosa MTCC2297. The characterization of metabolites produced by the microbes which are responsible for quorum-sensing inhibition through GC-MS is very scarce in scientific literature. The ethyl acetate extract of P. aeruginosa RKC1 inhibits biofilm formation of L. amnigena RCE while inhibiting growth at higher concentrations. The GC-MS analysis suggested that Cyclic dipeptides (CDPs) such as Cyclo (L-prolyl-L-valine), Cyclo (Pro-Leu), and Cyclo(D-phenylalanyl-L-prolyl) were predominantly found in the ethyl acetate extract of the P. aeruginosa RKC1 (93.72%). This diketopiperazine (DKPs) exhibited quorum-sensing inhibition against the pathogen in liquid media during the active growth phase and regulated diverse metabolites of the pathogen. Moreover, the metabolites data from the clear zone around wells showed a higher concentration of DKSs (9.66%) compared to other metabolites. So far, very few reports indicate the role of DKPs or CDPs in inhibiting the quorum-sensing system in plant pathogenic bacteria. This is one such report that exploits metabolites of P. aeruginosa RKC1. The present investigation provided evidence to use quorum-sensing inhibitor metabolites, to suppress microbes' pathogenesis and thus develop an innovative strategy to overcome antibiotic resistance.

Evaluation of anti-quorum sensing and antibiofilm effects of secondary metabolites from Gambeya lacourtiana (De Wild) Aubr. & Pellegr against selected pathogens

“…Violacein production, swarming motility and biofilm formation are amongst the important quorum-sensing mediated processes in bacteria. The disruption of quorum-sensing communication networks in bacterial colonies is an effective strategy to eliminate or reduce resistance to antibiotics and it is not intended to kill bacteria but to prevent the expression of their virulence factors and pathogenicity [ 27 ]. For this reason, violacein inhibition, anti-QS, swarming inhibition and antibiofilm assays were performed at concentrations below the minimal inhibitory concentration (sub-MIC).…”

The role of plant-associated rhizobacteria in plant growth, biocontrol and abiotic stress management

“…The plant's survival during a drought is guaranteed by PGPR through a variety of mechanisms, including osmotic adjustments, increased antioxidant activity, phytohormone production, etc., and these mechanisms also promote the plant's growth. Additionally, new developments in omics technologies have improved our understanding of PGPR, which makes it easier to investigate the genes involved in colonizing plant tissue (Baba et al, 2021; Jabborova et al, 2021, 2022; Kapadia et al, 2021; Kapadia, Kachhdia, et al, 2022; Kapadia, Patel, et al, 2022; Khan et al, 2021; Khumairah et al, 2022).…”

“…Generally, rhizobacteria improve plant growth by synthesizing phytohormones precursors (Dodd et al, 2010; Tsukanova et al, 2017), vitamins, enzymes, siderophores, antibiotics (Prakash et al, 2022) and inhibiting ethylene synthesis. Plant growth‐promoting rhizobacteria (PGPR) promote plant development through a broad range of mechanisms, such as biological nitrogen fixation, phosphate solubilization, rhizosphere engineering, siderophore output, 1‐Aminocyclopropane‐1‐carboxylate deaminase (ACC) output, quorum sensing (QS) signal intervention, production of phytohormone and inhibition of biofilm production (Kapadia, Kachhdia, et al, 2022; Kapadia, Patel, et al, 2022), having antifungal activity, synthesis of volatile organic compounds (VOCs), promoting beneficial plant‐microbe symbioses, systemic resistance induction (Prakash et al, 2022), etc. In the present review, we highlight recent studies addressing the role of PGPR as a biofertilizer, biopesticides and photostimulation used in equitable agriculture.…”

Antifungal activity of the endophytic Aspergillus against Candida albicans

“…Cyclo L-prolyl-L-valine was predominantly found in the ethyl acetate extract of the Pseudomonas aeruginosa RKC1 (93.7%). This diketopiperazine (DKPs) exhibited quorum-sensing inhibition against the pathogen in liquid media during the active growth phase and regulated diverse metabolites of the pathogen (Kapadia et al, 2022). Initially, antibiotics produced by Aspergilli were referred to as aspergillin (Blumenthal., 2004), but recent studies have shown that Aspergillus oryzae can produce various secondary metabolites, such as Aspergillormarasmine, Cyclopiazonic acid (CPA), kojic acid, 3nitropropionic acid, Maltoryzine, and Violacetine, which was reported as an antibiotic produced on malt extracts (Bhumenthal, 2004).…”