Peptide Mix from Olivancillaria hiatula Interferes with Cell-to-Cell Communication in Pseudomonas aeruginosa

Abstract

Bacteria in biofilms are encased in an extracellular polymeric matrix that limits exposure of microbial cells to lethal doses of antimicrobial agents, leading to resistance. In Pseudomonas aeruginosa, biofilm formation is regulated by cell-to-cell communication, called quorum sensing. Quorum sensing facilitates a variety of bacterial physiological functions such as swarming motility and protease, pyoverdine, and pyocyanin productions. Peptide mix from the marine mollusc, Olivancillaria hiatula, has been studied for its antibiofilm activity against Pseudomonas aeruginosa. Microscopy and microtiter plate-based assays were used to evaluate biofilm inhibitory activities. Effect of the peptide mix on quorum sensing-mediated processes was also evaluated. Peptide mix proved to be a good antibiofilm agent, requiring less than 39 μg/mL to inhibit 50% biofilm formation. Micrographs obtained confirmed biofilm inhibition at 1/2 MIC whereas 2.5 mg/mL was required to degrade preformed biofilm. There was a marked attenuation in quorum sensing-mediated phenotypes as well. At 1/2 MIC of peptide, the expression of pyocyanin, pyoverdine, and protease was inhibited by 60%, 72%, and 54%, respectively. Additionally, swarming motility was repressed by peptide in a dose-dependent manner. These results suggest that the peptide mix from Olivancillaria hiatula probably inhibits biofilm formation by interfering with cell-to-cell communication in Pseudomonas aeruginosa.

Chemical Composition and Biological Activities of the Essential Oils of Chrysophyllum albidum G. Don (African Star Apple)

“…Pseudomonas aeruginosa is a biofilm-forming organism [ 8 ]; hence the activity of the oils against this organism prompted us to investigate the biofilm inhibition potential of the fruit and leaf essential oil of Chrysophyllum albidum . Both fruit and leaf essential oil exhibited very good inhibitory properties, with percentage inhibition above 50% at all concentrations tested ( Table 5 ).…”

“…Essential oils could interfere with quorum sensing factors produced by Gram-negative and Gram-positive bacteria. Quorum sensing mediates virulence factors production, swarming motility, and biofilm formation in many bacteria [ 8 ]. Thus, interrupting the action of quorum sensing factors could also lead to antibiofilm action.…”

“…The wells were then stained with 0.1% crystal violet followed by elution into a new plate for absorbance reading at 595 nm. Biofilm inhibition was estimated from the following equation: where A c is the absorbance of the control and A t is the absorbance of the treatment groups [ 8 ].…”

“…Oftentimes, this mechanism developed by pathogens results in antibiotic resistance. Biofilm inhibition or removal is therefore a potentially attractive route for eliminating bacteria [ 8 ].…”

Molluscan Compounds Provide Drug Leads for the Treatment and Prevention of Respiratory Disease

“…Bacteriostatic effects on MRSA have been observed using compounds isolated from molluscan bacterial symbionts [ The capacity to form biofilms (structured communities of bacteria encapsulated within an extracellular polymeric matrix) confers some bacteria, including P. aeruginosa, an enormous advantage in establishing and maintaining infections in the respiratory tract [177]. Of interest therefore are studies by Gasu et al [178,179] using peptide extract of Olivancillaria hiatula establishing a relatively low MIC of 0.039 mg/mL against P. aeruginosa and 50% inhibition of biofilm formation at the same concentration, though 2.5 mg/mL was required to degrade pre-formed biofilm (Table 5). Further, the peptide extract reduced the expression of virulence factors (pyocyanin, pyoverdine, and protease) by >50% at 0.0195 mg/mL and acted synergistically with standard antibiotics ciprofloxacin and cefotaxime (up to 100% reduction in MICs) ( Table 5).…”