关键词: 发酵乳杆菌, 检测方法, 16S rDNA序列测定

Abstract: In recent years, the addition of probiotics to milk powder has gradually become a research focus. In order to ensure the product quality and safety, a microbiological detection method for Lactobacillus fermentum CECT5716 in milk powder has been established. It was found that the population of Lactobacillus fermentum in milk powder could be accurately counted by spreading serial 10-fold dilutions in buffered peptone water (BPW) onto MRS plates and culturing them under anaerobic conditions at (36 ± 1) ℃ for (48 ± 2) h, with clear discrimination from inoculated bifidobacteria. This method was more suitable for counting Lactobacillus fermentum than the Chinese national standard method (GB 4789.35?2016), and had the advantages of high discrimination capacity, short culture time, simple operation, good repeatability, and high accuracy. This method also included 16S rDNA sequence analysis of the strain for its subsequent molecular identification. There was no significant difference in the accuracy of this method versus the national standard method in detecting 20 samples prepared in our laboratory (P = 0.127).

Key words: Lactobacillus fermentum, test method, 16S rDNA sequencing