Novel Quorum Quenching YtnP Lactonase From Bacillus paralicheniformis Reduces Pseudomonas aeruginosa Virulence and Increases Antibiotic Efficacy in vivo

Abstract

Bacterial infections have become increasingly difficult to treat due to the occurrence of antibiotic-resistant strains. A promising strategy to increase the efficacy of therapy is to combine antibacterials with agents that decrease pathogen virulence via the modulation of the quorum sensing (QS). Lactonases inhibit acylated homoserine lactone (AHL)-mediated QS in Gram-negative bacteria, including the leading nosocomial pathogen Pseudomonas aeruginosa. Here we describe the characteristics of heterologously expressed YtnP lactonase from Bacillus paralicheniformis ZP1 (YtnP-ZP1) isolated from agricultural soil using the culture enrichment method. Purified YtnP-ZP1 hydrolyzed different AHLs with preference to substrates with long acyl residues as evaluated in assays with biosensors and HPLC. The enzyme showed good thermostability and activity in a wide temperature range. YtnP-ZP1 in 50 μg mL–1 concentration reduced the amount of P. aeruginosa-produced long-chain AHLs by 85%, while it hydrolyzed 50% of short-chain AHLs. Incubation of P. aeruginosa PAO1 with YtnP-ZP1 reduced its swarming motility and elastolytic activity without bactericidal effect. YtnP-ZP1 caused the inhibition of biofilm formation and disintegration of mature biofilms in P. aeruginosa PAO1 and multiresistant clinical strain BR5H that was visualized by crystal violet staining. The treatment with YtnP-ZP1 in concentrations higher than 25 μg mL–1 improved the survival of P. aeruginosa PAO1-infected zebrafish (Danio rerio), rescuing 80% of embryos, while in combination with tobramycin or gentamicin survival rate increased to 100%. The treatment of P. aeruginosa PAO1 biofilms on infected zebrafish tail wounds with 50 μg mL–1 YtnP-ZP1 and 2 × MIC tobramycin led to infection clearing in 2 days. The extensive toxicity studies proved YtnP-ZP1 was non-toxic to human cells and zebrafish. In conclusion, novel YtnP-ZP1 lactonase with its effective anti-virulence activity could be used to increase the efficacy of clinically approved antibiotics in clearing both systemic and biofilm-associated P. aeruginosa infections.

Potential of the quorum‐quenching and plant‐growth promoting halotolerant Bacillus toyonensisAA1EC1 as biocontrol agent

“…On the other hand, recent studies carried out by Djokic et al. ( 2022 ) showed that this enzyme in B. paralicheniformis ZP1 is highly effective in reducing the virulence of P. aeruginosa PAO‐1 in zebrafish. To our knowledge, this is the first time that this enzyme has been described in the species B. toyonensis .…”

“…Recently Peng et al (2021) have revealed that the YtnP protein of B. licheniformis strain T-1 causes a reduction in virulence of Aeromonas hydrophila ATCC 7966 in Carassius auratus both in vitro and in vivo. On the other hand, recent studies carried out by Djokic et al (2022) showed that this enzyme in B. paralicheniformis ZP1 is highly effective in reducing the virulence of P. aeruginosa PAO-1 in zebrafish. To our knowledge, this is the first time that this enzyme has been described in the species B. toyonensis.…”

Synergistic Antimicrobial Action of Lactoferrin-Derived Peptides and Quorum Quenching Enzymes

“…Such combinations can be based not only on AMPs or antibiotics [ 43 , 44 ], but also on enzymes that are active against different G(+) and G(−) bacteria [ 45 , 46 , 47 ]. In vitro studies of the combined use of various AMPs derived from human and bovine lactoferrin with traditional antibiotics revealed the presence of a synergistic effect between polypeptides and antibiotics; however, the obtained results were insufficient to produce therapeutic effects in vivo [ 48 ]. In this regard, the search for new solutions among possible combinations of AMPs from lactoferrin continues.…”

Anti-Quorum Sensing Activity of Probiotics: The Mechanism and Role in Food and Gut Health

“…QS was blocked through the degradation of QS signal molecules (AHL) by various species of B. paralicheniformis . Lactonase and acylase were found to degrade the lactone and acyl rings in the QS signal AHL, respectively [ 33 ]. Lb.…”