Bacillus subtilis BR4 derived stigmatellin Y interferes Pqs‐PqsR mediated quorum sensing system of Pseudomonas aeruginosa

Abstract

Cell‐to‐cell communication is essentially required in bacteria for the production of multiple virulence factors and successful colonization in the host. Targeting the virulence factors production without hampering the growth of the pathogens is a potential strategy to control pathogenesis. To accomplish this, a total of 43 mangrove isolates were screened for quorum quenching (QQ) activity against Pseudomonas aeruginosa (PA), in which eight bacteria have shown antibiofilm activity without hampering the growth of the PA. Prominent QQ activity was observed in Bacillus subtilis BR4. Previously, we found that BR4 produces stigmatellin Y, a structural analogue of PQS signal of PA, which could competitively bind with PqsR receptor and inhibits the quorum sensing (QS) system of PA. Further, stigmatellin Y containing ethyl acetate extract (S‐EAE) (100 µg ml−1) of BR4 significantly inhibits (p < 0.001) the biofilm formation of PA. Confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) analysis also fortified the QQ activity of BR4. Furthermore, S‐EAE of BR4 (500 µg ml−1) has significantly reduced the production of virulence factors, including protease, elastase, pyocyanin and extracellular polysaccharides substances. Furthermore, liquid chromatography–mass spectrometry (LC–MS)/MS analysis affirms that BR4 intercepts the PQS‐mediated QS system by reducing the synthesis of as many PQS signals, including precursor molecule (243.162313 Da) of PQS signal. Thus, S‐EAE of B. subtilis BR4 could be used as a promising therapeutic agent to combat QS system‐mediated pathogenesis of PA. Further therapeutic potentials of stigmatellin Y to be evaluated in clinical studies for the treatment of multidrug resistant PA.

Intercellular communication and social behaviors in mycobacteria

“…Hence, understanding the regulatory pathways could give insights into the molecular nature of mycobacterial infection (i.e., tuberculosis and leprosy). Key regulatory proteins of QS mechanisms could be used as a target to control pathogenesis (Boopathi et al, 2022b ). As mentioned before, key proteins that are conserved across mycobacteria may be involved in QS mechanisms of various mycobacterial species, which could be targeted as a common target to control various mycobacterial diseases.…”

Quorum sensing signals: Aquaculture risk factor

“…Many organisms, including bacteria, produce compounds (Table 2) that imitate QS signalling molecules and bind with cognate receptors to disable the QS system of the pathogens and suppress their virulence factors 110,111 . Many synthetic chemicals have been developed to inhibit pathogens' QS systems using the chemical modification principle 112,113 .…”

“…Many organisms, including bacteria, produce compounds (Table 2) that imitate QS signalling molecules and bind with cognate receptors to disable the QS system of the pathogens and suppress their virulence factors. 110,111 Many synthetic chemicals have been developed to inhibit pathogens' QS systems using the chemical modification principle. 112,113 Since bacteria produce QS signals through an autoregulatory QS mechanism, such QS analogues not only restrict the production of QS-mediated virulence factors but also QS signals.…”