Antimicrobial activity of coffee bagasse (Coffea arabica) extract against phytopathogenic bacteria and fungi

Plant diseases caused by microbial pathogens represent a major challenge for global agriculture, leading to annual crop losses estimated at more than USD 220 billion. The search for sustainable antimicrobial agents derived from agro-industrial by-products has gained increasing attention as an alternative to synthetic pesticides. Coffee bagasse, a major residue generated during coffee processing, retains a wide range of bioactive compounds with potential antimicrobial properties. This study aimed to evaluate the antibacterial and antifungal potential of an ethanolic extract of coffee bagasse against opportunistic strains relevant to agriculture. Chemical characterization (total phenols, total melanoidins, target analysis of phenolic compounds, caffeine, amino acids, and sugars) revealed main chemical compounds such as chlorogenic acid, gallic acid, caffeine, and melanoidins. The most abundant amino acids were serine, gamma-aminobutyric acid (GABA), alanine, and aspartic acid. Antimicrobial assays showed promising activity against phytopathogenic bacteria Erwinia amylovora and Dickeya dadantii . Fungi such as Alternaria alternata, Fusarium oxysporum , and Penicillium charlesii exhibited concentration-dependent susceptibility, with optimal inhibition at 10 mg/mL. These findings demonstrate the potential revalorization of coffee bagasse as a sustainable source of antimicrobial compounds with possible applications in plant disease management and food safety.