Antibacterial activity of Mexican oregano (Lippia graveolens H.B.K.) essential oil against of bacteria associated with postharvest spoilage of strawberries and tomatoes

Strawberries ( Fragaria × ananassa ) and tomatoes ( Solanum lycopersicum ) are highly perishable plant-based foods that are susceptible to postharvest spoilage caused by bacteria. The accurate identification of microorganisms associated with spoilage and the evaluation of natural antimicrobial compounds are essential for developing sustainable preservation strategies. This study aimed to isolate and molecularly characterize native bacterial strains associated with postharvest spoilage of strawberries and tomatoes, as well as to evaluate the in vitro antibacterial activity of Mexican oregano ( Lippia graveolens H.B.K.) essential oil against the isolated strains. Four bacterial strains were characterized by colony morphology, Gram staining, partial 16S rRNA gene sequencing, and phylogenetic analysis using the Neighbor-Joining method with 1,000 bootstrap replicates. The strains were classified into the genera Enterobacter and Bacillus , showing the greatest similarity to Enterobacter cloacae , Enterobacter hormaechei , Bacillus subtilis , and Bacillus mycoides . Although partial 16S rRNA gene sequences provided limited resolution at the species level for some strains, phylogenetic analysis supported their preliminary taxonomic classification. The antibacterial activity of Mexican oregano essential oil formulated as an emulsion was evaluated against the bacterial isolates. Complete inhibition of the Enterobacter isolates (SB1 and TB1) and one Bacillus isolate (SB2) was observed at concentrations as low as 0.05%, whereas the second Bacillus isolate (TB2) showed greater tolerance within the conditions evaluated. These findings expand current knowledge of the bacterial diversity associated with postharvest spoilage of strawberries and tomatoes and support the potential use of Mexican oregano essential oil as a promising natural alternative for controlling bacteria associated with postharvest spoilage.