|A fluorescent staining method for fast assessment of microbial quality of herbal medicines should be discovered in this study.
The number of total bacteria and esterase-active bacteria on powdered traditional Chinese medicines were enumerated by fluorescent staining method using 6-carboxyfluorescein diacetate (6CFDA) and 4`,6-diamidino-2-phenylindole (DAPI), and they were compared with colony-forming units (CFU).
The CFU was approx. 103 per gram in ginseng radix, and no bacterial colonies were detected from others. However, the total bacterial number (TDC) was more than 107 per gram, and number of bacteria possessing esterase activity ranged from 1 to 3% of TDC.
Many bacteria in each Chinese medicine had enzyme activity and most of them could not be detected by conventional plate counting technique.
Enumeration of bacterial cells on traditional Chinese medicines by fluorescent staining method requires less than 1 h.
The double staining method with 6CFDA and DAPI could be applicable to rapid microbial monitoring of crude drugs.
Source: Nakajima, K., Nonaka, K., Yamamoto, K., Yamaguchi, N., Tani, K. & Nasu, M. (2005): Rapid monitoring of microbial contamination on herbal medicines by fluorescent staining method. In: Letters in Applied Microbiology 40 (2), 128-132.
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