Diverse Forage Enhances the Antimicrobial Potency of Australian Honey

Antimicrobial resistance is a critical global health crisis, driving renewed interest in natural alternatives like honey. Australia's diverse native flora offers unique opportunities for producing bioactive honeys, yet their antimicrobial potential remains underexplored. This study aimed to systematically evaluate the antimicrobial activity and chemical composition of Australian honeys from post-bushfire New South Wales landscapes and to identify key drivers of bioactivity and their therapeutic potential. Antimicrobial activity was assessed against Staphylococcus aureus and Escherichia coli using broth microdilution methods, measuring both total activity and non-peroxide activity. Comprehensive chemical profiling included bioactive compounds, quality parameters, sugars, organic acids, amino acids, volatiles, and secondary metabolites, assessed using standardized methodologies and ¹H-Nuclear Magnetic Resonance spectroscopy. Statistical analyses included correlation analysis, LASSO regression modeling, and principal component analysis. Most honeys exhibited strong antimicrobial activity, with 77% achieving MICs of ≤ 10% (w/w) against both pathogens, and 25% achieving ≤ 5% (w/w) against at least one pathogen. Honeys produced from mixed flora had consistently high levels of antibacterial activity, while monofloral honeys were much more variable. H₂O₂ was the strongest single factor associated with antibacterial potency, explaining 45%-46% of the variability in MIC values among samples. Including additional chemical parameters in multivariate models improved the ability to predict antibacterial strength, explaining up to 59% of the variation for S. aureus, and 73% for E. coli. The superior performance of mixed-flora samples challenges conventional assumptions favoring monofloral products and supports biodiversity-focused beekeeping practices, providing a foundation for developing Australian honeys as therapeutic alternatives while supporting sustainable industry recovery.