The antibacterial and antifungal activity of honey and propolis from the Australian stingless bee Tetragonula carbonaria

The global rise of antimicrobial-resistant pathogens has increased interest in bee-derived natural products as sources of novel antimicrobials. While most research has focused on European honey bee (Apis mellifera) products, the 550 species of stingless bees found globally also produce honey and other hive products, representing a largely unexplored source of novel bioactives. This study investigates the antimicrobial activity of propolis extracts and honey from the Australian stingless bee Tetragonula carbonaria against 16 clinically significant bacterial and fungal pathogens, using broth microdilution methodology. T. carbonaria propolis and honey exhibited distinct antimicrobial profiles: propolis showed selective activity against a subset of bacteria and certain filamentous fungi, while honey showed broad-spectrum activity against all tested bacteria and selective activity against dermatophyte fungi. The level of H2O2 production in T. carbonaria honey was only moderately correlated with its antimicrobial activity, and the total phenolic content of propolis did not correlate significantly with its antimicrobial activity, suggesting other bee- or plant-derived compounds are important contributors. These findings highlight T. carbonaria propolis and honey as promising antimicrobials and potential sources of novel bioactive compounds.