Thin layer chromatographic determination of organic acids for rapid identification of bifidobacteria at genus level.

This study presents a simple and fast method for the identification of bifidobacteria using a thin layer chromatographic (TLC) analysis of the short chain fatty acids in a culture broth. When the chromatogram was sprayed with the indicator solution (methyl red-bromophenol blue in 70% ethanol), lactic acid exhibited two red spots, and acetic acid, propionic acid, and butyric acid all produced blue spots. Succinic acid and citric acid produced yellow and dark yellow spot, respectively. In addition, these organic acids showed different R(f) values. The total time taken to analyze the organic acids in the 10 bacterial culture broths using the proposed method was approximately 50 min. The proposed TLC method was used to analyze the organic acids in culture broths of the following strains, five Bifidobacterium species. (Bifidobacterium longum, B. breve, B. infantis, B. bifidum, and B. adolescentis) and five other lactic acid bacteria strains (Lactobacillus casei, L. bulgaricus, L. acidophilus, Streptococcus thermophilus, and S. lactis). Both spots of lactic acid and acetic acid were detected on all the TLC plates from the five bifidobacterial culture broths. The five other lactic acid bacterial culture broths, however, only exhibited lactic acid spots. Accordingly, the proposed TLC method would appear to be a useful tool for rapid identification of Bifidobacterium spp. at the genus level.