Antimicrobial Potential of Citrus limon Peel Essential Oil from Morocco: A Sustainable Approach to Citrus Waste Valorization

Abstract

Citrus peel residues are among the most abundant agro-industrial by-products, and their sustainable valorization offers a promising strategy to mitigate environmental impacts while generating value-added products for agriculture and health. In this study, approximately 130 lemon fruits were harvested from three representative orchards in the Pre-Rif region (Taza, Morocco) in March 2022. In each orchard, 5–10 trees were randomly selected, and 3–5 mature and healthy fruits were collected per tree. The peels were separated, washed, and subjected to hydrodistillation for essential oil (EO) extraction. The EO was chemically characterized by gas chromatography–mass spectrometry (GC–MS), following authentication of plant material through morphological and molecular identification. Twenty volatile compounds were identified, with D-limonene (46.89%) as the major constituent, followed by citral (8.32%), benzene (ethoxymethyl)- (7.86%), α-pinene (6.89%), cyclopentane bromo- (6.39%), and 1,2-bis(3-cyclohexenyl)ethylene (5.33%). Biological assays revealed strong broad-spectrum antimicrobial activity against clinically relevant pathogens: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Bacillus subtilis, and Candida albicans. The lowest Minimum Inhibitory Concentration (MIC) was recorded for C. albicans (1.66 mg/mL), while both S. aureus and P. aeruginosa showed pronounced bactericidal responses (MIC = MBC = 6.63 mg/mL). These findings demonstrate the potential of C. limon EO as a natural antimicrobial agent. By converting citrus peel waste into high-value bioproducts, this study highlights both environmental and socio-economic benefits, fostering eco-friendly biopesticides suitable for Integrated Pest Management (IPM) and reinforcing the circular bioeconomy in citrus-producing regions.