Analysis of contaminated microorganisms in commercial honey

Objective To investigate the microbial contamination in 54 batches of commercial honey.

Methods Aerobic plate colony counts for bacteria and colonies of mould and osmophilic yeasts in honey were determined according to the National Food Safety Standard. The bacteria and fungi in unqualified samples were further identified and analyzed by morphology， MALDI-TOF-MS and large subunit （LSU） rRNA gene sequence.

Results Three unqualified batches were found. One batch had aerobic plate colony counts exceeding the standard， with a variety of bacteria including Bacillus sp.， Paenibacillus sp. and Brevibacillus sp. Two batches had mould counts exceeding the standard. Aspergillus sp was detected in both samples （from the same manufacturer）， and the DNA sequence homology was very high， suggesting the mould might come from the same pollution source.

Conclusion There are many kinds of microbial contamination in honey. Manufacturers should strengthen the microbe control in monitoring process to avoid the repeated microbial contamination.