Abstract:

The objective of this study was to detect the aerobic plate count, and isolate and identify two food-borne
pathogens (Bacillus cereus and Cronobacter) in tea samples collected from local markets in Wuhan according to the Chinese
national standards. Bacillus cereus was identified by PCR analysis of 16S rDNA internal transcribed spacer (ITS) sequence
and Cronobacter by 16S rDNA and fusA sequence analysis. We further compared the detection rates of both bacterial
pathogens in tea samples from different producing areas and in different kinds of tea. Bacillus cereus was detected in 97.9%
of the investigated tea samples accounting for about 6.0% of the total bacterial population. Three strains of Conobacter spp.
were identified in 6.5% of these tea samples accounting for only 0.1%–3.2% of the total bacterial population. The highest
aerobic plate count and Conobacter spp. were found only in herbal tea. Fermented tea had the highest B. cereus counts,
exceeding 1 100 MPN/g in all samples. There were significant differences in the three microbial indicators among different
tea-producing regions. Thus, the food safety hazards of these food-borne pathogens cannot be ignored, especially when tea is
mixed with other materials.

Key words: tea, aerobic plate count, Cronobacter, Bacillus cereus, detection, identification