Molecular identification of major bacteria in honey and the effect of microwave treatment on its microbial quality and antibacterial activity

Abstract

The objectives of this study were to assess the microbial quality of honey, evaluate the effect of microwaves on microbial survival, and assess the antibacterial activity of honey. Bacteria, yeast and mold were evaluated in samples before and after microwave treatment. Dominant bacterial contaminants were also identified. The antibacterial activity of honey was assessed against nine pathogens using an agar well diffusion assay. The minimum inhibitory concentration was determined for four honey samples that exhibited the highest antibacterial activity. In addition, one sample of Manuka honey was tested to compare its microbial load as well as its antibacterial activity to local honey samples. Sequencing using 16S rRNA gene was used for the identification of dominant bacteria. The average standard plate count, yeasts and molds were 286.5, 161.0 and 25.5 CFU/g, respectively. Microwave treatment decreased microbial populations gradually with increasing power levels and exposure times. The present study indicated that raw honey had a significant antibacterial activity which decreased following microwave treatment. The identity of 125 isolates was confirmed with Bacillus being most frequently isolated.