Bioremediation-Associated Antibiofilm and Quorum-Sensing Inhibition by Pseudomonas aeruginosa Isolates from Petroleum-Contaminated Environments

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Petroleum-derived hydrocarbons represent a major environmental concern due to their persistence, toxicity, and disruptive effects on ecosystems. Bioremediation using hydrocarbon-degrading microorganisms has gained increasing attention as a sustainable strategy to mitigate such pollution. In this study, Pseudomonas aeruginosa isolates obtained from petroleum-oil-contaminated soils were screened for their quorum-sensing (QS) inhibitory and antibiofilm activities against pathogenic bacteria. Eleven isolates were identified and tested through agar well diffusion, violacein inhibition, and microtiter plate biofilm assays. Crude extracts significantly inhibited violacein production in Chromobacterium violaceum ATCC 12472, with dose-dependent suppression ranging from 17.8% to 72.5%. Isolates Z5 and Z10 exhibited the strongest quorum-quenching activities, while Z11 demonstrated high pigment inhibition (64.9% at 50 mg/mL) despite the absence of inhibition zones, suggesting violacein suppression independent of growth restriction. Biofilm inhibition assays revealed selective but substantial activity: Z3 and Z8 reduced Enterobacter aerogenes ATCC 51342 biofilms by 91% and 85%, respectively, whereas Z12 and Z13 inhibited Staphylococcus aureus ATCC 29213 (65% and 60%), Escherichia coli ATCC 25922 (71% and 70%), and Bacillus cereus 709 Roma (88% and 75%). No inhibition was observed against Pseudomonas aeruginosa ATCC 27853 or Listeria monocytogenes ATCC 7644. Overall, the findings suggest that petroleum-associated P. aeruginosa isolates may produce bioactive metabolites with dual anti-QS and antibiofilm functions. These properties not only highlight their ecological adaptation to hydrocarbon-polluted environments but also underline their potential as natural sources of bioactive compounds for bioremediation and antimicrobial applications. The strain-specific variability observed emphasizes the importance of screening environmental isolates for novel quorum-quenching agents with both environmental and clinical relevance.