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Updated: Feb 4, 2026

Improvement of Bacillus subtilis Spore Enumeration and Label Analysis in Flow Cytometry
Published on: June 30, 2023
The use of a simple flow cytometry method for rapid detection of spores in probiotic Bacillus
Xiao-Ling Zheng1, Zhi-Qiang Xiong2, Jie-Qun Wu3
11Zhejiang Institute for Food and Drug Control, Hangzhou, 310004 China.
Abstract:
Detection of the number of vegetative cells and endospores is necessary for quality control during the production of orally administered probiotic Bacillus licheniformis-containing tablets (BCT). However, there is no standard method for the rapid detection of vegetative cells and endospores in China. In this study, a simple flow cytometry (FCM) method was used to monitor the population dynamics of BCT. Using a specific fluorescent stain, SYBR green I, flow cytometric analysis could easily differentiate two morphological states of B. licheniformis. Compared with plate count assay (PCA) for determining the number of vegetative cells and endospores, the percentage of endospores determined by FCM was ~10% higher than that by PCA. Advantages of the FCM method over conventional methods include lower labor work, shorter detection time, and higher accuracy. Therefore, this simple FCM method could be a practical tool for monitoring quality control during the production of probiotic BCT.
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