At the crossroads of botanical origin, native microbiota and metabolome: a comparative study of Brazilian green propolis from distinct biomes

The chemical profiles of propolis and their botanical origins do not entirely match. Recent studies have shown that propolis has an active native microbiota that may contribute with its antimicrobial properties. The aim of the present investigation was to compare the native microbiota and the metabolome of two types of Brazilian green propolis occurring at distinct biomes, Cerrado (GP) and Caatinga (CP). Additionally, the native microbiota and the metabolome of the respective potential botanical origin of these propolis, Baccharis dracunculifolia (BD) and Mimosa tenuiflora (MT) was investigated. Bacterial and fungal communities were assessed by 16S rRNA and ITS regions sequencing, respectively, and the metabolomic profiles from green propolis and plant resins were analyzed by UPLC-ESI-QToF-MS/MS. Unique DNA sequences assigned to 465 bacteria and 829 fungi were found. Principal component analysis combined with K-means clustering analysis showed that the native microbiota of propolis types were significantly different, while the microbiota of the plant resins was similar (p < 0.05). Chemometric analyses showed high similarity between the metabolomes of GP and BD, while a lower similarity was observed between CP and MT, despite the presence of MT biomarkers in both of them. It indicates that MT was not the unique plant resin source for CP. Nevertheless, molecular networking analyses showed exclusive features for each propolis type derived from known flavonoids present in their respective potential botanical origins. Such flavonoid modifications could be attributed to microbial activity, although further research must be encouraged to confirm the effect of native microbiota on propolis' metabolome.